AP Physics I Semester One Final
A 9000 kg rock slides on a horizontal surface with negligible friction at 3 m/s toward a 3000 kg rock that is at rest, as shown in Figure 1. A collision occurs such that the two rocks remain stuck together and travel with a common final speed vf, as shown in Figure 2. What is the speed vf of the two-object system after the collision?
2.25 m/s
At time t=0s, object X of mass M travels at a constant speed of 2 m/s to the right toward object Y of mass 2M that is a distance of 8m away from object X while at rest, as shown above. Both objects are on a horizontal surface, where the frictional forces may be considered negligible. Which of the following pairs of force diagrams represents the forces exerted on object X and object Y at t=4 s
B - -I for object X and I- object Y, X being smaller than Y
A student pulls a block over a rough surface with a constant force FP that is at an angle θ above the horizontal, as shown above. If FP remains constant but the angle θ is increased, which of the following is true at some later time?
B - The force of friction between the block and surface will decrease.
Astronomers making careful observations of the moon's orbit discover that the orbit is not perfectly circular, nor is it elliptical. Which of the following statements supports this observation?
B - There is another celestial body that exerts a gravitational force on the moon
A student drops a rock from rest at a distance h above the ground such that the rock hits the ground at time t0. At what distance above the ground should the rock be dropped such that it hits the ground at a time 2t0 after it is released from rest?
D - 4h
A 5kg object is released from rest near the surface of a planet such that its gravitational field is considered to be constant. The mass of the planet is unknown. After 2s, the object has fallen 30m. Air resistance is considered to be negligible. What is the gravitational force exerted on the 5kg object near the planet's surface?
D - 75 N
A student uses a motion sensor to collect data of the velocity of an object as a function of time during two experimental trials, as shown. In which trial does the object have the greatest magnitude of acceleration, and in which trial does the object travel the greatest distance?
D - Greatest Magnitude of Acceleration = Trial 2 , Greatest Distance = Trial 1
Which of the following experiments could be used to determine the inertial mass of a block?
D - Use a spring scale to exert a force on the block. Measure the acceleration of the block and the applied force.
Which of the following is a correct ranking of the normal forces Fn1, Fn2, and Fn3 exerted on the boxes?
Fn3>Fn2>Fn1
How does the magnitude of the force exerted by the stick on the puck Fpuck,stick compare to the magnitude of the force exerted by the puck on the stick Fstick,puck at the time interval in which the stick is in contact with the puck?
Fpuck,stick=Fstick,puck
An Atwood machine is placed on a planet in which the acceleration due to gravity on the planet is unknown. Both ends of a light string are attached to two blocks such that M1 > M2, and the string passes through a pulley such that frictional forces are considered to be negligible, as shown above. The same tension force T is exerted on both blocks, and the block of mass M experiences an acceleration a, in the downward direction when released from rest. Which quantities would allow the acceleration due to gravity on the planet to be determined?
M1, M2, and ao
A student uses a motion sensor to collect data about an object's velocity v as a function of time t after it is released from rest near Earth's surface. The student claims that the graph shown represents the object while in free fall. Does the data from the graph support the student's claim?
No, because the slope of the curve of the graph indicates that the acceleration is less than g. which indicates that a force other than gravity is exerted on the object.
A student performs an experiment in which a ball travels in a perfect circle. The ball is attached to a string and travels in the horizontal, circular path, as shown in Figure 1. At time to, the ball has a speed vo. During the time interval of 0 s to 2 s, the force of tension in the string is recorded and graphed, as shown in Figure 2. Is the system consisting of the ball, string, and student an open system or closed system, and why?
Open system, because the force due to gravity from Earth is an external force that is exerted on the ball-string-student system
Objects X and Y are connected by a string of negligible mass and suspended vertically over a pulley of negligible mass, creating an Atwood's machine, as shown in the figure. The objects are initially at rest, and the mass of object Y is greater than the mass of object X. As object Y falls, how does the kinetic energy of the center of mass of the two-object system change? Justify your selection. All frictional forces are considered to be negligible.
The kinetic energy increases because the gravitational force due to Earth does positive net work on the system.
A small block of mass M = 0.10 kg is released from rest at point 1 at a height H = 1.8 m above the bottom of a track, as shown in the diagram. It slides down the track and around the inside of a loop of radius R= 0.6 m. The speed of the block is 2.5 m/s at point 3. Which of the following claims about the situation is correct?
The mechanical energy of the block-Earth system at point 3 is C less than the mechanical energy of the block-Earth system at point 1.
A ball of mass M is attached to a string of negligible mass that has a length R. The ball moves clockwise in a vertical circle, as shown above. Which of the following is true about the ball-string-Earth system as the ball moves from point 1 to point 2?
The potential energy decreases by 2M9R and the tension in the string increases by more than 2Mg.
Block X and block Y are tied together by a rope. The system containing block X and block Y is released from rest on a ramp, as shown in the figure. Block Y has a smaller mass than block X. Which of the following claims is correct regarding the momentum of the system containing only block X and the system that contains block X and block Y?
The system containing block X is an open system, and the system of both blocks is an open system.
Students attach a force probe in the middle of string A to measure TA and then use a different force probe to provide the applied force F to the box of mass m1. With the box of mass m3 held in place by one student, a second student pulls to the left on the force probe that provides the applied force F. As the second student pulls with a steady force, and with the boxes remaining at rest, the following pairs of readings from the two force probes are recorded at different times. Based on the measurements above, how do the magnitudes of the two force quantities compare?
The two quantities agree within experimental uncertainty but do not exactly agree numerically.
In the setup shown in the figure, two blocks of equal mass M are at rest but are just about to slip. Also shown is a free-body diagram for the block on top of the table. In this setup, the coefficient of static friction between the table and the block resting upon it must be
at least 1.0
A block of mass M is attached to a modified Atwood machine and is accelerated upward at 3a by a constant force F0. What is the weight of the block?
D - Mg
Identical spheres are dropped from a height of 100m above the surfaces of both Planet X and Planet Y. The position of the spheres as a function of time is recorded as the spheres fall. These data are shown in the graphs above. Which planet exerts a greater gravitational force on the sphere, and what evidence supports this conclusion?
D - Planet Y, because the magnitude of the slope of the curve increases at a faster rate.
A rock of mass M is thrown from the edge of a cliff of height h with an initial velocity vo at an angle 0 with the horizontal, as shown in the figure. Point P is the highest point in the rock's trajectory, and point Q is level with the initial position of the rock. All frictional forces are considered to be negligible. Which of the following could correctly describe the total energy of the rock-Earth system at points P and Q?
Point P Mgh +1/2mv^2 Point Q mgh+1/2mv^2
A ball of Mass M is swung in a vertical circle with a constant tangential speed. Figure 1 shows the forces exerted on the ball at the top of the circle, and Figure 2 shows the forces exerted on the ball at the bottom of the circle. Which of the following is an expression for the centripetal acceleration of the ball in terms of M, T1, T2, and any fundamental constants?
T+T /2M
Three blocks with masses m1, m2, and m3 are attached by strings, as shown in the figure above. The coefficient of friction between each of the blocks and the horizontal surface is μ. The tension in the left and right strings is T2 and T1, respectively. If the acceleration of the blocks is a, which of the following expressions is equal to T2 ?
T1−m2a−μm2g
A planet orbits a star along an elliptical path from point X to point Y, as shown in the figure. In which of the following systems does the total mechanical energy of the system remain constant?
The closed system containing the planet and the star
A toy car of mass 2 kg travels along a horizontal surface with negligible friction at a speed of 1.0 ". The car then collides with a vertical wallI. The wall applies a force of magnitude 20 N for 0.2 s on the toy car. Which of the following predicts the motion of the toy car immediately after the collision?
The speed of the car will remain the same, and the car will travel in the opposite direction.
Consider the trial in which the ramp is at a 20° angle with the horizontal. The surface of the ramp has been replaced with a surface in which frictional forces are considered to be negligible. If the mass of the block is doubled and the initial launch speed is doubled, how could the student predict the new vertical of the block at point B?
Use 1/2mv^2 initial- mgy final to solve for yf
Which of the following free body diagrams could be used to analyze the forces exerted on the moon when it is at the position indicated in the figure?
A - 0-> Fgravity
A motorized cart is attached to a string that passes over a pulley. The other end of the string is attached to a hanging block. In the figure shown above, the cart is accelerating to the right. Which of the following best represents the forces acting on the cart at the instant shown?
C
Consider scenario 1. Is the object X-object Y system open or closed? Predict whether both the momentum and the kinetic energy of the system will be the same or different after the collision.
Closed Same Changes
A block is placed on an inclined plane and remains stationary, as shown in the figure above. A student claims, "The block remains stationary because as gravity tries to pull the block down the ramp, the block exerts an equal and opposite force on itself up the ramp." Is the student's claim correct? Justify your answer.
D - No. Newton's third law states the block cannot exert a force on itself.
A block of mass of 10 kg travels in the positive direction along a surface with negligible friction. The block has an initial momentum 18 The block collides kg-m with an object of an unknown mass that is at rest. The force exerted on the block as a function of time is shown on the graph. Which of the following best predicts the speed and direction of the block immediately after the collision?
Decreases Same Direction
A block slides with constant velocity down a rough inclined plane that makes an angle of θ with the horizontal. It experiences three forces: gravitational (Fg), normal (FN), and frictional (Ff). Which of the following gives the magnitude of the net force on the block?
Zero
Student X ties one end of a string to a 0.5 kg ball and swings the ball in a vertical circle of radius1m, as shown in the figure. Student Y uses video analysis to determine the speed of the ball at points A, B, C, and D, as shown in the table. Student X states that the data are incorrect because the tension in the string provides a centripetal force that should cause the ball to travel with a constant tangential speed. Is Student X's reasoning correct, and why or why not?
No. because the net centripetal force exerted on the ball is the combination of the tension force from the string and the force due to gravity from Earth.
A toy car has an initial acceleration of 2 m/s across a horizontal surface after it is released from rest. After the car travels for a time t = 5 seconds, the speed of the car is 25 m/s. Is the system consisting of only the car an open system or a closed system, and why?
Open system, because an external force is applied to the car that causes it to accelerate
A cart is attached to a hanging block by a string that passes over a pulley, as shown in the figure. The pulley has negligible friction in its axle and negligible mass. A student must determine the change in momentum of the cart as it is pulled across the horizontal surface from the moment the cart is released from rest to the moment immediately before the cart collides with the pulley. Which of the following lists the measuring devices that are needed to determine the change in momentum of the cart?
Timer, mass balance, and meterstick
A block on a rough, horizontal surface is attached to a horizontal spring of negligible mass. The other end of the spring is attached to a wall. The spring is compressed such that the block is located at position X. When the block-spring system is released, the block travels to the right through position Y and continues to travel to the right through position Z. Free body diagrams for the block at positions X, Y, and Z are shown in the figure. At which position does the block have the greatest kinetic energy?
Y
A small object of mass M is shot horizontally from a spring launcher that is attached to a table. All frictional forces are considered to be negligible. The ball strikes the ground a distance D from the base of the table, as shown in the figure. A second object of mass is launched from the same launcher such that the spring is compressed the same distance as in the original scenario. The distance from the base of the table that the object lands is
greater than D but less than 2D
A block of mass 3kg on a horizontal surface travels at 6m/s toward the free end of a horizontal spring of negligible mass and spring constant k=200N/m , as shown in the figure. The other end of the spring is attached to a wall, and there is negligible friction between the block and the horizontal surface. The block comes into contact with the free end of the spring such that the block remains fixed to the spring as the spring is compressed. A graph of the kinetic energy of the block as a function of the distance the spring is compressed is shown that was collected from experimental data. Which of the following data tables could best represent the spring potential energy of the block-spring system as a function of the distance that the spring is compressed?
(0,0) (.3,9) (.6,36)
A student swings a ball of mass M on the end of a string in a vertical circle of radius R, as shown in the top figure above. Also shown is a diagram representing all of the forces exerted on the ball at the bottom of the circle, where its speed is v0. What is the magnitude of the acceleration of the ball at the bottom of the circle?
(FTension − FGravity)/M
Astronaut X of mass 50 kg floats next to Astronaut Y of mass 100 kg while in space, as shown in the figure. The positive direction is shown. Astronaut X applies a force against Astronaut Y such that the kinetic energy of each astronaut as a function of time is shown in the graph. What is the change in momentum of the two-astronaut system and the change in momentum of each astronaut from immediately before the force was applied to immediately after the force was applied?
0,-100, 100
Block X and block Y travel toward each other along a horizontal surface with block X traveling in the positive direction. Block X has a mass of 4kg and a speed of 2ms. Block Y has a mass of 1kg and a speed of 1 ms. A completely inelastic collision occurs in which momentum is conserved. What is the approximate speed of block X after the collision?
1.4m/s
When the object is located at the position shown in Figure 3, which of the following equations correctly indicates the total mechanical energy of the object-spring-Earth system?
1/2k0x^2-mgx0
A car travels with a tangential speed v1 around a curve of radius r and turns to the left, as shown by the rear view of the car in Figure 1. A force diagram of the forces exerted on the car with speed of 5m/s as it turns is shown in Figure 2. A force diagram of the forces exerted on the car with speed v as it turns around the same curve of the same radius is shown in Figure 3. The speed v of the car in figure 3 is most nearly
15m/s
An object travels in the positive direction with a momentum of 5 kg⋅ms . An applied force is exerted on the object, and a graph of the magnitude of the applied force as a function of time is shown. All frictional forces are considered to be negligible. Which of the following could represent the approximate momentum of the object after the force has been applied? Select two answers.
3kgm/s, 7kgm/s
At one point in their individual orbits, three planets, X,Y,& Z, are along the same horizontal line. The gravitational force on Planet X from Planet Z is F0. The distance from the center of mass of each planet to an adjacent planet is given in terms of R0, and their respective masses are given in terms of M0, as shown above. What is the net force on Planet Y, and what reasoning supports this claim?
5F0 to the right, because the gravitational force from Planet Y is greater than the gravitational force from Planet X.
Block X and block Y travel toward each other along a horizontal surface with block X traveling in the positive direction. Block X has a mass of 2kg and a speed of 3m/s. Block Y has a mass of 1kg and a speed of 3m/s. After the collision, block X travels in the horizontal direction with a speed of 1m/s in the negative direction. What is the speed of block Y if the collision is elastic?
5m/s
Block A of mass 4m is attached by a light string to block B of mass 2m. The string passes over a pulley with negligible friction and of negligible mass. Block A is held a distance h above the ground, as shown. The blocks are released from rest, and block A reaches the ground two seconds later. The value of h is most nearly
6.7m
Block X of mass M slides across a horizontal surface where friction is negligible. Block X collides with block Y of mass 2M that is initially at rest, as shown in Figure 1. After the collision, both blocks slide together with a speed vs , as shown in Figure 2. What is the kinetic energy of the two-block system before the collision?
9/2 Mv^2
A student places a block on a disk, and the edge of the disk makes one revolution in a constant time interval △t. A force probe is attached to the block and the center of the disk, as shown above. In an experiment, a student measures the centripetal force exerted on the block when placed at various distances from the center of the disc while the tangential speed of the edge of the disc remains constant. Which of the following graphs shows the centripetal force exerted on the block as a function of its distance from the center of the disk?
A
Two containers of water can have their individual masses varied by adding or removing water. The containers are initially a distance d apart, as measured from their centers, and are filled with water so that each had a mass M, as shown in Figure 1 above. The gravitational force that one container exerts on the other is F0. Water is then added to one container so that it's mass increases to 1.5M, and water is removed from the other container so that it's mass decreases to 0.5M, as shown in Figure 2. What is the new gravitational force exerted on one container by the other?
A - 3/4 F0
Block X travels towards Block Y that is initially at rest, as shown in the figure, and eventually collides with Block Y. Which of the following diagrams represents the final velocities for Block X and Block Y after the collision if the collision is elastic?
C 2.4m/s 6.4m/s
A rocket on Earth experiences an upward applied force from its thrusters. As a result of this force, the rocket accelerates upward at 2 m/s2. Assume that there are no other upward forces exerted on the rocket and that wind resistance is negligible. Which of the following combinations of the rocket's mass mRocket and force from its thrusters FThrusters would result in an upward acceleration of 2 m/s2? Select two answers.
A and B 1kg 12N, 3kg 36N
Consider a runner in any of the lanes moving at a known, constant tangential speed. Which of the following measuring tools, if any, could be used to experimentally determine the centripetal acceleration of the runner?
A meterstick
A scientist designs an experiment that requires two atomic particles whose only fundamental force exerted between them is the gravitational force. Which combination of particles and separation distance will meet this condition? A proton and neutron located 1.0 mm apart
A proton and neutron located 1.0 mm apart
A block of mass M on an inclined surface is attached to a spring of negligible mass, as shown. The other end of the spring is attached to a wall, and there is negligible friction between the block and the incline. The block is pulled to a position such that the spring is stretched from its equilibrium position. The block is then released from rest. Which of the following systems can be classified as a closed system?
A system consisting of the block, spring, and Earth
In which of the following situations is the gravitational force the dominant force? Select two answers.
A)A satellite is in orbit around a planet. B) An object is in free fall just after it is released from rest.
A constant force FA is applied to an object of mass M, initially at rest. The object moves in the horizontal x-direction, and the force is applied in the same direction. After the force has been applied, the object has a speed of vf. Which mathematical routines can be used to determine the time in which the force is applied to the object of mass M? Select two answers.
A,B
A student conducts three experiments to determine how certain quantities influence the centripetal force responsible for an object to spin in a horizontal circle. The student uses one end of a string to attach the object while the other end is connected to a force sensor that allows the student to change the tension on the string, as shown in the figure. The student records data from the three experiments in the table above. Which of the following experiments, if any, collected data that do not agree with the expression for the net centripetal force on the object?
All the data are expected.
A student must design an experiment to determine the acceleration of a cart that rolls down a small incline after it is released from rest. The student has access to a timer, a meterstick, and a slow-motion camera that takes a photograph every 160 of a second. The angle that the incline makes with the horizontal is unknown, and the length of the incline is unknown. Which of the following procedures could the student use to determine the cart's acceleration? Select two answers.
B - Use the timer to record the time it takes the cart to travel alongside a meterstick that is attached to the incline C - Use the slow-motion camera to film the cart as it rolls down the incline alongside a meterstick that is attached to the incline.
A person kicks a ball into the air with a force F0. The figure shows the position of the ball at various times. What is the net force on the ball and its acceleration at the highest point shown?
B, Force=mg Acceleration=g
A cart of mass M travels from point A at height h1 above the ground to point B on a track that is at a height h2, as shown in the figure. The speed of the cart at point A is nearly zero, and the frictional forces between the wheels, cart, and track are considered to be negligible. Which of the following graphs could represent the potential energy of the cart-Earth system at point A and point B? Select two answers.
B,C
A block is initially sliding along a surface of negligible friction with a speed v0. A constant force F0 is then exerted on the block. Which of the following figures represents the situations in which the kinetic energy of the block will initially decrease? Select two answers.
B,D
Three blocks are sliding together to the right along a surface of negligible friction when a force with magnitude Fext is exerted to the left on the rightmost block, as shown in the figure. The masses of the blocks are indicated in the figure. If the force is exerted for a time Δt, what is the change in velocity of the center of mass of the three-block system?
Fext/6mΔt
A planet orbits a star in the path shown in the figure. The planet's mass is much smaller than the star's mass. Which two of the following claims are correct about the accelerations associated with the planet, star, and planet-star system? Select two answers. Justify your selections.
Both the planet and the star accelerate, because each object exerts a force on the other object. AND The center of mass of the planet-star system does not accelerate, because there is no net force exerted on the system.
How could a student verify that the collision under consideration is an inelastic collision for the two-block system?
By comparing the final kinetic energy of the system with the initial kinetic energy of the system
A truck in a traffic circle travels in a circular path at constant speed v0 while passing through region X of the circle, as shown in Figure 1 above. A diagram representing the forces exerted on the truck in region X is shown in Figure 2. At a later time a car with less mass than the truck passes through region X at the same speed and the same distance from the center of the traffic circle as the truck. The coefficient of friction between the car's tires and the ground is the same as that for the truck's tires and the ground. Which of the following diagrams could represent the forces exerted on the car in region X compared to the truck in region X ? Assume that the length of each arrow is proportional to the magnitude of the force represented by the arrow.
C
An object starts at rest and moves in a horizontal circle such that its tangential speed increases linearly as a function of time. Which of the following graphs shows how the centripetal acceleration behaves as a function of time?
C
Cart X with a mass of 1kg is released from rest at the top of an inclined ramp, and the cart rolls down the ramp with negligible friction. At the bottom of the ramp, cart X collides with cart Y, which is initially at rest. The collision is completely inelastic, and both cart X and cart Y have equal masses. Before and after the collision, data are collected about the distance d each cart travels as a function of time t. The table shows data about cart X before the collision as it travels down the ramp. Which of the following sets of data could represent the collision for cart X and cart Y?
C
Planet X is in a stable circular orbit around a star, as shown above. Which of the following graphs best shows the tangential speed of the planet as a function of its horizontal position from point A to point B if the planet is moving counter clockwise as viewed in the figure above?
C
The following figures each show vectors representing the forces exerted on an object that is initially at rest. In which case will the object remain at rest?
C
Identical objects, Object X and Object Y, are tied together by a string and placed at rest on an incline, as shown in the figure. The distance between the center of mass of each object is 2m. The system of the two objects is released from rest, and a graph of the system's center of mass velocity as a function of time is shown. Based on the data, approximately how much time will it take the center of mass of Object X to reach point J near the bottom of the incline?
C - 3.0 s
A block travels across a horizontal surface in which frictional forces are not considered to be negligible, as shown in the figure. Which of the following quantities should a student measure to verify that the direction of the frictional force exerted on the block from the surface is in the same direction as the change in momentum of the block? Select two answers. Justify your selections.
C,D - The initial velocity, because the initial momentum of the block is proportional to the final momentum of the block. The final velocity, because the initial momentum of the block is proportional to the final momentum of the block.
A student must conduct an experiment to verify the conservation of momentum. Cart X and Cart Y travel toward each other and eventually collide, as shown in the figure. The student has access to the two carts, one mass balance, and two motion detectors. If the mass of each cart is known, how should the student arrange one or both motion detectors so that the student can collect enough information about the motion of the carts, in order to verify the conservation of momentum of the system?
D
Two satellites orbit a planet of mass M, as shown above. Satellite A of mass 2 m travels in a circular orbit of radius R. Satellite B of mass m travels in a circular orbit of radius 2 R. Each satellite travels at a constant tangential speed. How does the gravitational force, FgA, exerted on satellite A from the planet compare with the gravitational force, FgB, exerted on satellite B from the planet?
FgA is larger than FgB because satellite A is twice as large as satellite B and is half the distance to the planet as satellite B.
An object is placed on a rotating disk. The amount of time it takes the object to make one revolution around the center of the circle may be set at a known value. Which of the following procedures could be used to make the necessary measurements to find the coefficient of static friction between the object and the disk's surface?
D-Place the object on the disk and measure the distance from the center of the disk to the center of mass of the object by using a D meterstick. Slowly increase the rate the disk rotates until the object begins to slide off the disk. Record the time in which the object makes one revolution around the center of the disk.
A block of mass M slides with speed v0 at the bottom of a ramp of negligible friction that has a height H, as shown. How do the total mechanical energy of the block alone and the total mechanical energy of the block-Earth system change when the block slides up the ramp to point P?
Decreases,Remains Constant
Two blocks of mass 2 kg and 3 kg are connected by a light string that passes over a pulley, as shown above. The pulley has negligible mass and friction. The two-block system is released from rest. Which of the following correctly describes the velocity of the two-block system's center of mass?
Direction of Velocity: Downward Magnitude of Velocity: Increasing
Now consider four runners running around the track with the same constant tangential speed, with one runner in each lane of the track. A student is considering using the following equations to determine which runner has the greatest acceleration.
Equation 2, because the radius of the circular path traveled by a runner determines the acceleration of the runner.
After the object reaches the position in Figure 3, the spring pushes the object upward until the object is no longer in contact with the spring. A graph of the force exerted by the spring on the object as a function of the position of the object is shown. How much work does the spring do on the object as it pushes the object upward until the object is no longer in contact with the spring?
F0x0/2
A 3kg object experiences a rightward horizontal acceleration of 6m/s2 as it slides to the right across a rough, horizontal surface. The table above contains the label and magnitude of four forces exerted to the right or left on the object that represent measurements from an experiment as the object accelerates. Which pair of opposing forces in which directions could be responsible for the acceleration of the object?
F3 to the right and F2 to the left
Consider a runner in lane 1 with a speed v1 and a runner in lane 4 with a speed v4, where the ratio of the speeds v4/v1 is 2. The radius of lane 4 is b times the radius of lane 1, and both runners have the same mass. Which of the following claims is correct about the net forces F1 and F4 exerted on the runners in lanes 1 and 4, respectively?
F4 is equal to 4/b*F1
A satellite orbits Earth in a circular path at a constant tangential speed, as shown in the figure. Which of the following correctly represents the directions of the net force FNet , acceleration a, and tangential velocity vT of the satellite at the instant shown in the figure?
FNet↑av↑T→
A 1kg block is placed near the top of an inclined plane that is at an angle of 30 degrees with respect to the ground, as shown above. By correctly determining the effect of gravity, a student predicts that the acceleration of the block will be 5m/s2. After allowing the block to slide down the inclined plane, the student finds that the acceleration is actually 4m/s2. What type of force did the student most likely not account for when predicting the acceleration of the block, and what is the magnitude of that force?
Force of friction of approximately 1N
A block of mass M is placed on a semicircular track and released from rest at point P, which is at vertical height H1 above the track's lowest point. The surfaces of the track and block are considered to be rough such that a coefficient of friction exists between the track and the block. The block slides to a vertical height H2 on the other side of the track. How does H2 compare to H1?
H2<H1
One end of a string is attached to a ball, with the other end held by a student such that the ball is swung in a horizontal circular path of radius R at a constant tangential speed. At a later time, the tension force exerted on the ball remains constant, but the length of the string is decreased to R4. What is the new tangential speed of the ball?
Half the original speed
A student must test the maximum force exerted on an object attached to a string before the string breaks. The student ties the object of mass m0 to one end of the string and then uses the other end of the string to spin the object at a constant speed so that the object travels in a horizontal circular path, as seen in Figure 1. Figure 2 shows the horizontal force exerted on the object at time t0. In a second trial, what should the student do to increase the tension in the string while keeping all other quantities constant? Select two answers.
Increase the mass of m0m0. AND Decrease the time required for one rotation.
A planet orbits a star along an elliptical path, as shown in the figure. Consider the system consisting of the planet and the star. How do the magnitude of the force exerted on the planet by the star and the total mechanical energy of the system change as the planet moves from point X to point Y?
Increases, Remains constant
An object of mass M is dropped near the surface of Earth such that the gravitational field provides a constant downward force on the object. Which of the following describes what happens to the center of mass of the object-Earth system as the object falls downward toward Earth?
It does not move
A student must determine the effect of friction on the mechanical energy of a small block as it slides up a ramp. The block is launched with an initial speed vn from point A along a horizontal surface of negligible friction. It then slides up a horizontal, as shown in the figure. The student measures the maximum vertical ramp, where friction is not negligible, that is inclined at angle 0 with respect to the height h attained by the block while on the ramp, labeled as point B in the figure. At point B, the block comes to rest. The student performs three trials with the ramp at different angles, launching the block at the same initial speed vo for each trial. The results from the trials are displayed in the table.
K< Ko, because the force of friction removes mechamcal energy from the block-ramp-Earth system on its way up the ramp and back down the ramp.
The figure above shows two identical asteroids that are located near each other but are not in contact. Various locations are also labeled on the asteroids. If an astronaut wants to stand on one of the asteroids and experience the largest net gravitational force, where should the astronaut stand?
Location A
A block is at rest on a disk that spins about its center, as shown. A student must determine the centripetal acceleration of the block when the block spins with the disk as a result of the force of static friction. What measuring devices, when used together, could be used to determine the centripetal acceleration of the block? Select two answers.
Meterstick AND Stopwatch
A student must perform an experiment to determine the work done by a spring as it launches a block across a horizontal surface. The spring is initially compressed and the block is initially held at rest. After the spring is uncompressed, the block is no longer in contact with the spring. The spring constant is unknown, and the student may not use the mass or weight of the block in the experiment for any calculation. Which of the following measuring tools, when used together, can be used to determine the work done by the spring on the block? Select two answers.
Meterstick and force sensor
A student must perform an experiment in which two objects travel toward each other and collide so that the data collected can be used to show that the collision is elastic within the acceptable range of experimental uncertainty. Which of the following measuring tools, when used together, can the student use to verify that the collision is elastic? Select two answers.
Motion detector and balance
A student must conduct an experiment in which an elastic collision occurs. In the experiment, Block X of mass 2kg travels with a velocity vX in the positive direction toward Block Y of mass 2kg that is at rest, as shown in Figure 1. After the collision, Block Y travels in the positive direction with velocity vY while Block X remains nearly at rest. Data collected of the initial and final velocities of both blocks for three trials of the experiment are shown in the table. Did the student conduct an experiment in which an elastic collision occurred? Is the system of Block X and Block Y open or closed?
No, Open
A student conducts three experiments in which two carts, cart 1 and cart 2, travel toward each other and collide. A graph of each cart's momentum as a function of time is shown above. In which experiment, if any, does the graph indicate the presence of a net external force exerted on the two-cart system?
None of the experiments indicate the presence of a net external force.
Two ice skaters, Skater X and Skater Y, are at rest on a horizontal surface made of ice. The friction between the ice and the skaters is negligible. Skater X, who has a smaller mass than Skater Y, pushes Skater Ysuch that Skater Y travels with a speed of 2vo to the right. Which of the following indicates the direction of the velocity of Skater X and the direction of the velocity of the center of mass of the two-skater system after the push?
Skater X To the left, Center of Mass Zero
A square block is attached to a string of negligible mass and moves in a horizontal circle at a constant speed. The string passes through a vertical tube, and its other end is attached to a cylinder, as shown in the figure. Which of the following claims can be made by relating one of Newton's laws of motion to an object that travels in uniform circular motion?
The block exerts a force on the string.
A long wooden board is at rest on a horizontal surface, and there is negligible friction between the board and the surface. A block is sliding along the board, and there is friction between the block and the board. At the instant shown in the figure, the block is moving but the board is still at rest. What happens to the board and block after the instant shown, and what reasoning supports this claim?
The board starts moving in the same direction as the block and the block is slowing down, because the board exerts a force on the block and the block exerts a force on the board.
Two astronauts of identical mass are connected by a taut cable of negligible mass, as shown in the figure above, and are initially at rest with respect to a nearby space station. Astronaut Y pulls on the cable toward herself with considerable force. Which of the following describes the direction of the velocity of the center of mass of the two astronauts after Astronaut Y pulls on the cable?
The center of mass does not move.
A student conducts an experiment to verify whether momentum is conserved for a situation in which a collision occurs. The two objects, Object X and Object Y, travel toward each other, as shown in Figure 1. After the collision, the two objects travel as shown in Figure 2. Data collected from three trials of this experiment are shown in the table. Which of the following statements is correct based on the data?
The conservation of momentum can be verified within the threshold of experimental uncertainty.
Block X of mass 2kg travels across a horizontal surface toward block Y of unknown mass that is initially at rest. Block X then collides elastically with block Y. A graph of the position as a function of time for block X is shown. Block X and block Y are made of the same material. Which of the following predictions is correct about the motion of block Y immediately after the collision?
The kinetic energy of block Y immediately after the collision is greater than the kinetic energy of block Ximmediately after the collision.
Two objects of the same mass travel in opposite directions along a horizontal surface. Object X has a speed of 5 Im and object Y has a speed of 5 , as shown in the figure. After a period of time, object X collides with object Y. In scenario 1, the objects stick together after the collision. In scenario 2, the objects do not stick together after the collision.
The kinetic energy of the system in scenario 1 will be less than that in scenario 2 after the collision.
A falling skydiver opens his parachute. A short time later, the weight of the skydiver-parachute system and the drag force exerted on the system are equal in magnitude. Which of the following statements predicts the motion of the skydiver at this time?
The skydiver is moving downward with constant speed.
An experiment is conducted in which a cart travels across a horizontal surface and collides with a wall. Data collected from the experiment are used to create the graph of the cart's velocity as a function of time. All frictional forces are considered to be negligible. Which data from the graph should the student use to determine the direction of the net force exerted on the cart and the direction of the change in momentum of the cart from the time intervals of A to B?
The slope of the line from A to B, because that will provide information about the acceleration of the cart.
Block X of mass M slides across a horizontal surface where friction is negligible. Block X collides with block Y of mass 2M that is initially at rest, as shown in Figure 1. After the collision, both blocks slide together with a speed vs , as shown in Figure 2. What is the speed of the center of mass of the two-block system immediately before the collision?
The speed is vs
A student performs an experiment in which an applied force is exerted on a 4kg object that is initially at rest. In the experiment, the applied force is exerted on the object until the object has moved a known distance. In all the experiments the applied force is exerted in the direction of motion. A motion detector measures the speed of the object after it has traveled the distance under consideration for a given trial. The table contains the data that were collected for three trials of the experiment. Which of the following conclusions can be drawn from the data? Select two answers.
The total mechanical energy after a given trial is equal to the kinetic energy of the object at the end of the experiment. AND Another external force must have done work on the object because the final kinetic energy of the object is less than the work done on the object by the applied force.
An experiment is conducted such that an applied force is exerted on an object as it travels across a horizontal surface with a constant speed. A graph of the applied force exerted on the object as a function of the object's distance traveled is shown. Which of the following claims is correct regarding the work done on the object by the applied force from one data point to the next data point?
The work done remains nearly constant for all displacements.
A variable applied force is exerted on a 2kg block as it travels across a horizontal surface for a time of 2s, as shown in the graph. Before the force is applied to the block, it travels with a speed of 1 ms. The force is exerted on the block in the same direction as the block's displacement while the force is exerted. After the force is applied to the block, the block travels with a speed of 5 ms. Which of the following statements are correct regarding the motion of the block? Select two answers.
There must be another force exerted on the block during the time in which the applied force is exerted. AND The change in momentum of the block from the applied force is 5 kg⋅ms
A roller coaster track at a park includes a loop of radius R. A cart of mass M is located at the peak of the track, which has a height of 4R. The cart is subsequently released from rest such that it can slide down the track and go around the loop, as shown in the figure above. All frictional forces are considered to be negligible. Which of the following expressions for the cart's initial and final kinetic energy KE and the cart-Earth system's initial and final gravitational potential energy Ug could be used to determine the speed vf of the cart when it reaches the top of the loop?
Ug0=4MgR KE0=0 Ugf=2MgR KEf=12mv2f
How should the student use the data collected and the known quantities from the experiment to determine the initial total mechanical energy of the block-ramp-Earth system for all trials in the experiment?
Use K=1/2mv^2 with the block's initial speed for one trial because the initial speed is the same in all trials.
During an experiment, a toy car accelerates forward for a total time of 5 s. Which of the following procedures could a student use to determine the average net force exerted on the car during the 5 s that the car accelerates?
Use a balance to determine the mass car. Use a motion sensor to measure the speed of the car at a time of 0 s and a time of 5 s.
A student must determine the work done on an object when an external force is exerted on it after it travels a specific distance. An external force F is exerted on an object at position x = 0 by a string as the object moves a distance D across a horizontal surface for a time tf . The force changes such that it decreases as the object moves. Which procedure could be used to determine the work done on the object by the external force?
Use a spring scale that is tied to the free end of the string and a meterstick to measure the force exerted on the object and the corresponding position for several positions until the object travels a distance DD . Graph the force on the vertical axis and the position on the horizontal axis. Determine the area bound by the curve and the horizontal axis.
An object falls toward Earth after it is released from rest, as a result of Earth's gravitational force. A student uses a motion detector to create the graph of the object's displacement as a function of the squared time in which the object was in free fall. How can the student use the graph to determine the acceleration ay of the object while in free fall?
Use the slope of the graph and set it equal to 1/2ay to then solve for ay.
A student uses a motion detector to record the speed of a 2kg object as a function of time as it travels across a horizontal surface of negligible friction. Data from the experiment are shown in the graph. In addition to the known mass, how can a student use the graph to determine the work done on the object from 0s to 5s ?
Use ΔK=12mΔv2 with v0 equal to the speed of the object at 0s and vf equal to the speed of the object at 5s.
Cart X travels in the positive direction along a horizontal surface, and cart Y travels in the positive direction. The carts collide, and a student collects data about the carts' velocities as a function of time before, during, and after a collision, as shown. The masses of both objects are known. Which of the following best indicates how the student should use the graph to determine whether the collision is elastic or inelastic and provides a correct justification?
Using the known mass and known velocity for each cart to determine the kinetic energy of the system before and after the collision, because the kinetic energy changes in an inelastic collision
Which of the following describes the total mechanical energy of the object-Earth system during the time in which the object is in the air and the time in which the object is in contact with the spring? Assume all frictional forces are considered to be negligible.
constant, not constant
Block X of mass M travels with a speed v0. Block Y of mass 2M travels with a speed 2v0. Both blocks travel toward each other and collide. After the blocks collide, they separate so that the kinetic energy of the system remains conserved. Which of the following equations for the conservation of momentum could a student use to help determine the speed vf of each block after the collision?
m0v0−4m0v0=m0vXf+2m0vYf, because the two blocks initially travel in opposite directions, and the blocks do not stick after the collision
A block of mass M is held at rest on an inclined ramp that can be considered frictionless. The ramp makes an angle θ with the horizontal, as shown in Figure 1. When released, the block slides down the incline and comes into contact with an uncompressed spring with spring constant k0 . The block slides an additional distance x0 before it compresses the spring a maximum distance, as shown in Figure 2. A student wants to use the law of conservation of energy to analyze the energies associated with the block-ramp-spring-Earth system. Which of the following equations should the student use to analyze the specific forms of energy in the system from the instant the block is released to the instant that the spring is at its maximum compression? Select two answers.
mg(y0−yf)=12kx20mg(y0−yf)=12kx02 , because the initial gravitational potential energy of the system is converted into spring potential energy. (A) AND mgy0=mgyf+12kx20mgy0=mgyf+12kx02 , because some of the initial gravitational potential energy of the system is converted into spring potential energy. (B)
A satellite moves in a circular orbit at a constant speed v0 around Earth at a distance R from its center. The force exerted on the satellite is F0. An identical satellite orbits Earth at a distance of 3R from the center of the Earth. How does the tangential speed, vT, of the satellite at distance 3R compare to the speed v0 of the satellite at R?
vT=1/root 3 *v0
A moon of mass 1 x 1020 kg is in a circular orbit around a planet. The planet exerts a gravitational force of 2 x 1021 N on the moon. The centripetal acceleration of the moon is most nearly
20m/s^2
A 5 kg block moves with a constant speed of 10 " to the right on a smooth surface where frictional forces are considered to be negligible. It passes through a 2.0 m rough section of the surface where friction is not negligible, and the coefficient of kinetic friction between the block and the rough section Hk is 0.2. What is the change in the kinetic energy of the block as it passes through the rough section?
20 J of energy is removed from the block.
A force is applied to a 2 kg object, and measurements of the force as a function of time are shown. The force is the only force exerted on the object and is applied in the direction of the object's velocity. Which of the following could represent the initial velocity, vo, and the final velocity, vf, of the object?
4 m/s 6 m/s
A 2 kg object is released from rest near the surface of a planet with a negligible atmosphere. A graph of the object's speed v as a function of time t is shown. What is the weight of the object on the planet?
8N
Car X and car Y travel on a horizontal surface along different parallel, straight paths. Each car's velocity as a function of time is shown in the graph. Which of the following claims is correct about car X and car Y?
A - Both car X and car Y travel in the same direction
Two experiments are conducted to determine the mass of an object. In experiment one, the objects weight is measured by using an electronic balance once the object has been placed at rest on the balance. In experiment two, the object is pulled along a horizontal surface with a spring scale such that the force reading on the spring scale remains constant while a motion detector is used to measure the instantaneous speed of the object as it is pulled. all frictional forces for both experiments are considered to be negligible. Which of the two experiments, if either, could be used to determine the gravitational mass of the object?
A - Experiment 1 only
A toy car has a battery-powered fan attached to it such that the fan creates a constant force that is exerted on the car so that it is propelled in the opposite direction in which the fan blows air. The car has a carriage that allows a student to attach objects of different masses, as shown above. The fan has only one speed setting. All frictional forces are considered to be negligible. Which of the following procedures could be used to determine how the mass of the fan-car-object system affects the acceleration of the system?
A - Measure the mass of the system using a balance, activate the fan, measure the distance traveled by the system at a known time by using a stopwatch, and repeat the experiment for several trials with different objects added to the carriage.
Planet X has a mass of M and a radius of R. Planet Y has a mass of 3M and a radius of 3R. Identical satellites orbit both planets at a distance R above their surfaces, as shown above. The planets are separated by such a large distance that the gravitational forces between them are negligible. How does the gravitational field gx at the surface of Planet X compare with the gravitational field of gy at the surface of Planet Y?
B - gx = 3gy
A student must conduct two experiments so that the inertial mass and gravitational mass of the same object can be determined. In the experiment to find objects gravitational mass, the student ties one end of a string around the object with the other end tied to a spring scale so that the object can vertically hang at rest. In the experiment to find the objects inertial mass, the student uses a spring scale to pull the object, starting from rest, across a horizontal surface with a constant applied force such that the frictional forces are considered to be negligible. In addition to the spring scale, the student has access to other measuring devices commonly found in the science laboratory. Which of the following lists essential measuring devices the student can use to collect the data necessary to find the objects gravitational and inertial mass?
A - Meterstick and timer
An object is at rest on the ground. The object experiences a downward gravitational force from Earth. Which of the following predictions is correct about why the object does not accelerate downward? Select two answers. Justify your selections.
A - The bonded molecules of the object are repelled upward by the bonded molecules of the ground with the same magnitude as the gravitational force downward on the object. B - The normal force is exerted upward on the object from the ground with the same magnitude as the gravitational force downward on the object.
A student sets up an experiment to determine the inertial mass of a cart. The student has access to the following measurement equipment: a spring scale, a meterstick, and a stopwatch. The student uses the spring scale to pull the cart starting from rest along a horizontal surface such that the reading on the spring scale is always constant. All frictional forces are negligible. In addition to the spring-scale reading, which two of the following quantities could the student measure with the available equipment and then use to determine the inertial mass of the cart? Select two answers.
A - The total distance traveled by the cart after it has been in motion D - The time during which the cart is in motion
Two objects, object X and object Y, are held together by a light string and are released from rest near a planet's surface in the orientation that is shown in the figure. Object X has a greater mass than object Y. A graph of the acceleration as a function of time for the system's center of mass is shown for the 4s. The positive direction is considered to be upward. How does the speed of object X vx compare to that of the system's speed vs after the objects have fallen for 4s ?
A - Vx = Vs
An object is held at an unknown height above Earth's surface, where the acceleration due to gravity of the object is considered to be constant. After the object is released from rest, a student must determine the object's speed the instant the object makes contact with the ground. Which of the following equations could the student use to determine the object's speed by using the fewest measuring tools if the student does not have access to a motion sensor? Select two answers.
A - Vx = Vx0 + axt C - V^2x = V^2x0 + 2ax (x-x0)
Satellite A orbits a planet at a distance d from the planet's center with a centripetal acceleration a0. A second identical satellite B orbits the same planet at a distance 2d from the planet's center with centripetal acceleration ab. What is the centripetal acceleration ab in terms of a0?
A - a0/4
An object travels along a straight, horizontal surface with an initial speed of 2 ms. The velocity of the object as a function of time is given in the table above. Which of the following graphs represents the object's acceleration as a function of time?
A - straight horizontal slope
Toy car W travels across a horizontal surface with an acceleration of aw after starting from rest. Toy car Z travels across the same surface toward car W with an acceleration of az after starting from rest. Car W is separated from car Z by a distance d. Which of the following pairs of equations could be used to determine the location on the horizontal surface where the two cars will meet, and why?
A - x=x0+v0xt+12axt^2 for car W, and x=x0+v0xt+1/2axt^2 for car Z. Since the cars will meet at the same time, solving for t in one equation and placing the new expression for t into the other equation will eliminate all unknown variables except x
A student must determine the inertial mass of a block attached to a horizontal track. The block is free to move horizontally along the track, as shown above. Frictional forces are considered to be negligible. The student may only choose two measuring tools to determine the inertial mass of the block. What tools should the student choose? Select two answers. Accelerometer Force sensor
Accelerometer and Force sensor
A student performs several experiments in which two carts collide as they travel along a horizontal surfac Cart X and Cart Y both have a mass of 1 kg. Data collected from the three experiments are shown in the table. During which experiment does the center of mass of the system of two carts have the greatest change in its momentum?
All experiments have the same change in momentum for the center of mass of the system of two carts.
The moon has a mass of 1 x 10^22 kg, and the gravitational field strength at a distance R from the planet is 0.001 N/kg. What is the gravitational force exerted on the moon while it is in orbit around the planet?
B - 1 x 10^19
A ball traveling at a speed of v0 rolls off a desk and lands at a horizontal distance x0 away from the desk, as shown in the figure. The ball is then rolled off of the same desk at a speed of 3 v0. At what horizontal distance will the ball land from the table?
B - 3x0
The two blocks eventually stop and reverse direction. Which of the following graphs best predicts the acceleration of block A as it moves up and down the rough, inclined surface? Assume that the positive direction points down the slope.
B - Both lines in positive quadrant, first above the second
A student uses an electronic force sensor to study how much force the student's finger can apply to a specific location. The student uses one finger to apply a force on the sensor, and data collected from two trials are shown in the table. During which trial, if any, does the student's finger experience the greatest electromagnetic force?
B - Trial 2, because the student's finger applied the largest force to the sensor.
Rock X is released from rest at the top of a cliff that is on Earth. A short time later, Rock Y is released from rest from the same location as Rock X . Both rocks fall for several seconds before landing on the ground directly below the cliff. Frictional forces are considered to be negligible.Which of the following graphs correctly shows the vertical velocity of rock X as a function of time? Take the positive direction to be upward.
B - straight downward slope
An object travels along a straight, horizontal surface with an initial speed of 2 ms. The position of the object as a function of time is given in the table. Which of the following graphs represents the object's velocity as a function of time?
B - straight upward slope
If the mass of block B is 2kg, the gravitational force exerted on block B is most nearly which of the following?
C - 20N
Planet X has a mass of M and a radius of R. Planet Y has a mass of 3M and a radius of 3R. Identical satellites orbit both planets at a distance R above their surfaces, as shown above. The planets are separated by such a large distance that the gravitational forces between them are negligible. How does the magnitude of the gravitational force Fy exerted by Planet Y on its satellite compare to the gravitational force Fx exerted by Planet X on its satellite?
C - Fy = 3/4 Fx
Two objects, X and Y, move toward one another and eventually collide. Object X has a mass of 2M and is moving at a speed of 2v0 to the right before the collision. Object Y has a mass of M and is moving at a speed of v0 to the left before the collision. Which of the following describes the magnitude of the forces F the objects exert on each other when they collide?
C - The force exerted by X on Y is F to the right, and the force exerted by Y on X is F to the left.
A satellite orbits Earth. The only force on the satellite is the gravitational force exerted by Earth. How does the satellite's acceleration compare to the gravitational field at the location of the satellite? Select two answers.
C - The gravitational field and the acceleration point in the same direction. D - The magnitudes of the acceleration and the gravitational field strength are equal.
A spring-loaded launcher has a mass of 0.60 kg and is placed on a platform 1.2m above the ground. The force of friction is negligible between the platform and the launcher. The launcher fires a 0.30kg ball that lands a distance D to the right of the platform, as shown in the diagram above. Which of the following explanations is true?
C - The launcher will fall off the platform and land D/2 to the left of the platform because the launcher is twice the mass of the ball.
An object is launched upward at angle θ0 above the horizontal with a speed of v0. The trajectory and three positions of the object, X, Y, and Z, are shown in the figure. Position X is higher than position Z with respect to the ground, and position Y is at the object's maximum vertical position. Which of the following claims is correct about the system that consists of only the object?
C - The object's acceleration is the same at positions X, Y, and Z
The table shows the vertical position as a function of time for an object that is dropped from a height of 5 m. A student must determine the acceleration of the object. Which of the following procedures could the student use to make the determination? Justify your selections. Select two answers.
C - Use y=y0+vy0t+1/2ayt^2, since all quantities are known except for the acceleration due to gravity D - Create a position-versus-time graph of the ball's motion, and use the data to create a velocity-versus-time graph of the ball's motion, since the slope of the velocity-versus-time graph represents the acceleration
The amusement park ride shown above takes riders straight up a tall tower and then releases an apparatus holding seats. This apparatus free-falls back to Earth and is stopped safely right above the ground. Which of the following indicates the magnitude of the gravitational force exerted on a rider of mass m on the way up and on the way down?
C - Way Up and Way Down is Equal to Mg
Rock X is released from rest at the top of a cliff that is on Earth. A short time later, Rock Y is released from rest from the same location as Rock X. Both rocks fall for several seconds before landing on the ground directly below the cliff. Frictional forces are considered to be negligible. Which of the following graphs best represents the vertical displacement of Rock X as a function of time starting from immediately after the rock is released from rest? Take the positive direction to be downward.
C - upward slope
An object of mass M is placed on a disk that can rotate. One end of a string is tied to the object while the other end of the string is held by a pole that is located at the center of the disk. Initially, the object is spun in a horizontal circle of radius Rat a onnect constant tangential speed of vo, as shown in the figure, such that the tension in the string is T. At a later time, the disk is spun such that the tangential speed of the object is increased to 2vo . At a later time, the tangential speed of the object is increased to 3vo. Which of the following diagrams could represent the forces exerted on the object at one of the given speeds? Assume that the force of static friction is negligible. Select two answers.
C-4T, D-9T
Rock X is released from rest at the top of a cliff that is on Earth. A short time later, Rock Y is released from rest from the same location as Rock X. Both rocks fall for several seconds before landing on the ground directly below the cliff. Frictional forces are considered to be negligible. After Rock Y is released from rest several seconds after Rock X is released from rest, what happens to the separation distance S between the rocks as they fall but before they reach the ground, and why? Take the positive direction to be downward.
D - S increases because at all times Rock X falls with a greater speed than Rock Y
A 1500kg car traveling along a road is hit by a 0.1kgrock that creates a small crack in the car's windshield. Which of the following describes the interaction between the windshield and the rock?
D - The car exerts a force on the rock, and the rock exerts a force on the car. The two forces are equal in magnitude.
Two students, Student X and Student Y, stand on a long skateboard that is at rest on a flat, horizontal surface, as shown. In order to get the student-student-skateboard system to accelerate, Student X claims that Student Y should apply a force on Student X while both students stand on the skateboard. Which of the following statements is true regarding the claim made by Student X?
D - The claim is incorrect because both students are internal to the student-student-skateboard system, and internal forces within a system cannot cause the system to accelerate
Students connect a spring scale to a block on a rough horizontal surface. The students use the spring scale to measure the magnitude of the horizontal force needed to pull the block at a constant speed. Which of the following statements explains why two forces exerted between objects are equal in magnitude?
D - The frictional forces that the block and the surface exert on each other, because objects always exert forces of equal magnitude on each other.
Two identical blocks, block A and block B, are placed on different horizontal surfaces. Block A is initially at rest on a smooth surface, while block B is initially at rest on a rough surface. A constant horizontal force of magnitude F0 is exerted on each block. After the force has been applied for a time Δt, the speeds of blocks A and B are vA and vB, respectively. Which of the following claims indicates the correct relation between vA and vB and provides the best justification for the relation?
D - vA>vB. The forces between the atoms in a block and the atoms in a surface oppose the motion of the block and are greater, on average, for block B.
Object X collides into object Y and exerts a force on object Y while both objects are in contact. A graph of the force that object X exerts on object Y is shown. How could the graph be used to determine the change in momentum of object Y during the collision?
D-By determining the area bound by the curve and the horizontal axis from 0 s to 0,01 s
Given that m3>m2>m1, how do the force F and string tensions TA and TB compare?
TB<TA<F
A student conducts an experiment in which a cart is pulled by a variable applied force during a 2s time interval. In trial 1, the student exerts the force on a cart of mass M. In trial 2, the student exerts the force on a cart of mass 3M. In trial 3, the student exerts the force on a cart of 5M. In which trial will the cart experience the greatest change in momentum from 0s to 2 s?
The change in momentum is equal for all three trials from Os to 2s.
Which of the 5 kg object near Earth's surface is released from rest such that it falls a distance following correctly identifies whether the object-Earth system is open or closed and describes the net external force?
The system is open and the net external force is zero
A mass M, slides along a horizontal surface and collides with and sticks to a mass M2 that is initially at rest at the bottom of a ramp, as shown in Figure 1. Frictional forces between the masses, the surface, and the ramp are considered to be negligible. After the collision, masses M, and M2 slide together up the curved come to rest at their highest position along the ramp. Which of the following claims ramp as a total mass of M12 , as shown in Figure 2. The two masses eventually is correct regarding the momentum of the system of mass M, and the system of mass M, and M2 in terms of their momenta?
The system of mass M1 is an open system, and the system of mass M, and M2 is an open system.
The total mechanical energy of a system as a function of time is shown in the graph. Which of the following statements is true regarding the system?
The system should be classified as an open system because mechanical energy can be added and removed from the system.
Which of the following statements best describes the force or forces exerted on the puck after it is hit by the stick and slides on the ice?
There is no frictional force exerted on the puck, and the gravitational force and normal force are exerted on the puck and are equal in magnitude.
A student analyzes data of the motion of a planet as it orbits a star that is in deep space. The orbit of the planet is considered to be stable and does not change over time. The student claims, "The only experimentally measurable external force exerted on the planet is the force due to gravity from the star." Is the student's claim supported by the evidence? What reasoning either supports or contradicts the student's claim?
Yes. Other external forces are exerted on the planet, but they are of negligible magnitude.
A student is trying to determine the tensions in the strings connecting the boxes. If the acceleration of the system and the pulling force F are known, which of the following pairs of equations could be used to find the tensions?
m3a3=TBm3a3=TB and m2a2=TA−TB