AP Physics I Semester One Final

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

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

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.

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

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

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 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 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.

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.

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

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

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

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

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

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

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.

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.

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.

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.

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.