AP Physics Final Review

Consider the two spheres, A and B, placed near each other. Each sphere has its own radius and the surfaces of the spheres are a distance d apart, as shown. If you are calculating the gravitational attraction between spheres A and B, what quantity would go in the denominator of Newton's law of

(rA+d+rB)^2

A car moves from position A to position B. The smaller vector shows the cars initial position and the larger vector shows the cars final position. Which of the following vectors best represents the cars displacement from point A to Point B?

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One end of a vertical spring is attached to the ground with the other end above the ground such that the spring is at its equilibrium position. The spring has negligible mass and a spring constant k0 , as shown in Figure 1. When an object of mass m0 is released from rest above the spring, the object falls and then makes contact with the top of the spring with a speed v0 , as shown in Figure 2. The spring then compresses such that the object reaches a position x0 below the spring's equilibrium position, as shown in Figure 3, where the object comes to rest. The object is then directed upward by the spring until it is no longer in contact with the spring. The object then continues upward. The object-spring-Earth system has zero gravitational potential energy at the instant shown in Figure 2. All frictional forces are considered to be negligible. 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.

-In Air: Constant -Contact with Spring: not constant

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. 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. -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.

A block of mass M is held at rest on an inclined ramp that 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)=1/2kx^20 , because the initial gravitational potential energy of the system is converted into spring potential energy. -mgy0=mgyf+1/2kx^20 , because some of the initial gravitational potential energy of the system is converted into spring potential energy.

A weightlifter brings a 400-N barbell upward from his shoulders to a point 50 cm higher at a steady speed. During this process, what is the total work done on the barbell?

0 joules

A weightlifter exerts an upward force on a 1000-N barbell and holds it at a height of 1 meter for 2 seconds. Approximately how much power does the weightlifter exert on the barbell during this time?

0 watts

The force of gravity on object A by object B is F. If the mass of object B was only half as large as it is, but everything else was kept the same, what would be the new force of gravity on object B by object A?

1/2F

One end of a vertical spring is attached to the ground with the other end above the ground such that the spring is at its equilibrium position. The spring has negligible mass and a spring constant k0 , as shown in Figure 1. When an object of mass m0 is released from rest above the spring, the object falls and then makes contact with the top of the spring with a speed v0 , as shown in Figure 2. The spring then compresses such that the object reaches a position x0 below the spring's equilibrium position, as shown in Figure 3, where the object comes to rest. The object is then directed upward by the spring until it is no longer in contact with the spring. The object then continues upward. The object-spring-Earth system has zero gravitational potential energy at the instant shown in Figure 2. All frictional forces are considered to be negligible. 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^20-mgx0

The force of gravity on object B by object A is F. If the distance between the objects was tripled, but everything else was kept the same, what would be the new force of gravity on object B by object A?

1/9F

A 5 kg block moves with a constant speed of 10 ms 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 μk 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.

The force of gravity between object A and B is F. If the mass of object A was twice as large as it is, but if everything else was kept the same, what would be the new force of gravity between objects A and B?

2F

An object is dropped from the top of a building and hits the ground 3 seconds after it is released. What is the approximate speed of the object at the instant it hits the ground?

30 m/s

A weightlifter exerts an upward force on a 1000-N barbell and lifts the barbell 1 meter upward in 2 seconds. Approximately how much power does the weightlifter exert on the barbell during this time?

500 watts

Instead of dropping a ball, you throw a ball directly downward. After releasing the ball, what is the magnitude of its acceleration?

9.8 m/s^2

In the motion diagram,a car is moving to the right are equal time increments between frames. Velocity vector are drawn to show the speed and direction of the motion. What is the direction of the car's acceleration vector?

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You are lying on your back on the slope of a grassy hill, watching the clouds go by overhead. Which is the best statement about the force of friction exerted on you by the ground in this situation?

A force of static friction pointing "up the hill", parallel to the surface of the hill, is applied to you by the ground.

Which of the following velocity versus time graph best represents the motion of a ball that was thrown upward,from just before it is caught down

A graph going down through the x-intercept

Which of the falling objects is considering to be in free fall?

A hammer that is tossed upward by an astronaut on the moon (where there is no atmosphere)

This position versus time graph exhibits what kind of motion between points Q and R?

A moving object that is speeding up

The velocity versus time graph represent motion going up. What is true about the objects motion?

A moving object that is speeding up at a constant rate

Kepler's third law of planetary motion states that which two quantities are related?

A planet's orbital period and the size of the planet's orbit are related.

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

The velocity versus time graph represent a straight line. What true about the object motion?

An object moving at a constant speed

The position versus time graph exhibition the one dimensional motion of an object. At which instant in time does the objects velocity have the greatest magnitude?

At point R

In both figures, a particle of mass m is released from rest at a height, h. In figure (a), the particle is dropped straight downward and in figure (b) the particle is released from rest down a frictionless ramp. Which particle, the one in figure (a) or (b), will have more kinetic energy at the bottom?

Both particles will have the same kinetic energy at the bottom.

The motion of two cars, A and B, is describing with these position versus time graphs,what can you conclude about the cars?

Car A is driving at a faster constant speed than car B

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?

Distance Spring Is Compressed(m):0.0,0.3,0.6 Spring Potential Energy(J): 0,9,36

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.

F0 and v0 makes an obtuse angle

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

What the best description of g?

G is the magnitude of the acceleration due to the force of gravity

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

Newton's first law is a description of what basic property of our universe?

Inertia

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?

Initial Energy: Ug0=4MgR KE0=0 Final energy: Ugf=2MgR KEf=12mv2f

When you drop a ball, what is true about its motion

It falls and increases in speed at a rate of 9.8 m/s every second

Josh punches his open left hand with his right hand. Which statement is true about the forces his two hands exert on each other?

Josh's right hand and left hand exert equal and opposite forces on each other.

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 v0 from point A along a horizontal surface of negligible friction. It then slides up a ramp, where friction is not negligible, that is inclined at angle θ with respect to the horizontal, as shown in the figure. The student measures the maximum vertical 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 v0 for each trial. The results from the trials are displayed in the table. Consider the trial with the 45° ramp. Suppose the block is launched up the ramp such that it comes to rest at point B and then travels down the ramp. Which of the following best describes the block's kinetic energy KA when it reaches point A at the bottom of the ramp in comparison to the initial kinetic energy K0 before it travels up the ramp?

KA<K0 because the force of friction removes mechanical energy from the block-ramp-Earth system on its way up the ramp and back down the ramp.

While sparring, Katie punches Arman in the shoulder. Which statement is true about the forces Katie and Arman exert on each other?

Katie exerts a force on Arman's shoulder and Arman exerts a force on Katie's hand.

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 planetterm-25 moves from point X to point Y?

Magnitude of Force Exerted on Planet by Star:Increases Total Mechanical Energy of Planet and Star:Remains Constant

Which of the following is an important difference between an object's mass and its weight?

Mass and weight have different units.

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?

Mechanical Energy of Block: Decrease Mechanical Energy of Block-Earth System:remains constant

Michael leans on a shopping cart, causing it to start moving. Which statement is true about the forces Michael and the cart exert on each other?

Michael and the cart exert equal and opposite forces on each other.

Miguel leans against a wall. Which statement is true about the forces Miguel and the wall exert on each other?

Miguel and the wall exert equal and opposite forces on each other.

Acceleration can be expressed in units of m/s2 or __________.

N/kg

Jack and Luis are pushing on opposite ends of a shopping cart. At the moment, the cart is staying at rest. We know that the forces each person exerts on the cart are equal in magnitude and opposite in direction. What is the reason this must be true?

Newton's second law tells us these two forces must be equal and opposite.

Forces can be expressed in units of __________.

Newtons or pounds

An arrow is in mid-flight on its way to a target. At this moment, what force keeps the arrow going forward?

No force is pushing the arrow forward.

A communications company requests that their satellite be placed 100,000 meters above the Earth's surface and then launched so that it moves in a geosynchronous orbit (meaning an orbit that takes exactly 24 hours to complete). Is this possible?

No, orbiting every 24 hours only happens at one specific orbital distance.

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 t0, the ball has a speed ν0. During the time interval of 0s to 2s, 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

A toy car has an initial acceleration of 2m/s2 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 25m/s. Is the system consisting of only the car an open system or a closed system, and why?

Open system,becuase an external force is applied to the car that causes it to accelerate

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.

Point A has more than Point B

A rock of mass M is thrown from the edge of a cliff of height h with an initial velocity v0 at an angle θ 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+12Mv20 Point Q;Mgh+12Mv20

Suppose you are floating in deep space (in a space suit). You grab onto two identical toolboxes, one of which is full of metal tools and the other of which is empty. As you shake the two tool boxes around by their handles, which is the correct statement about what you would notice?

Suppose you are floating in deep space (in a space suit). You grab onto two identical toolboxes, one of which is full of metal tools and the other of which is empty. As you shake the two tool boxes around by their handles, which is the correct statement about what you would notice?

If every object is attracted to every other object in the universe via gravity, why is it that you feel only one force of gravity on a day-to-day basis (the one from Earth)?

The Earth is big enough and close enough to cause a noticeable effect.

Kepler's first law of planetary motion tells us that planets move in ellipses. If we picture the elliptical orbit of a planet orbiting the Sun, where does the Sun fit into the picture?

The Sun is at one focus of the ellipse, with nothing at the other focus.

If you know all of the forces acting on an object and you know the mass of that object, what quantities can you figure out from that information?

The acceleration of the object

A ball is dropped off of a tall building and falls for 6 seconds before landing on the ground. Consider how far the ball falls in its first 3 seconds of free fall (from t = 0 s to t = 3 s) compared to how far it falls in its next 3 seconds (from t = 3 s to t = 6 s).

The ball falls farther in the second 3-second interval than it does in the first interval.

When you throw a ball directly upward,what is true about its acceleration?

The balls acceleration is always directed downward

In the motion diagram,a car is driving to the right and there are equal time increments between frames. How is the car moving

The car is slowing down

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

Which of the following is a legitimate way to describe the force between a skydiver and the air she is falling through as the skydiver is falling toward the ground?

The drag force exerted by the air on the skydiver

A block of mass m is attached to a horizontal spring and rests on a flat, smooth surface as seen in the figure. If you push on the block in the negative x-direction to compress the spring and then release the block, what happens to the energy in the system immediately after the block is released?

The elastic potential energy in the spring decreases while the kinetic energy of the block increases.

Allison shoves her brother Brody away from her, causing him to fall down. Which of the following is an action-reaction pair (from Newton's third law)?

The force from Allison on Brody and the force from Brody on Allison form an action-reaction pair.

Which of these is a valid force that could be exerted on a car racing through narrow city streets?

The force of friction between the road and the car (its tires)

When helping a friend move into a new home, you push a chair across the room. What do you know about the force of gravity applied to the chair?

The force of gravity applied to the chair does not change the energy of the system (the chair) and therefore does no work on the system.

Which of the following is a legitimate way to describe the force between a skydiver and the earth as the skydiver is falling toward the ground?

The force of gravity exerted by the earth on the skydiver

When trying to analyze the forces in a situation we sometimes invent forces that don't actually exist. Which of these forces is NOT a valid force that could be exerted on a sled being pulled along a snowy path by a girl?

The force of motion pushing the sled forward

Blocks A and B have equal masses and are connected by a rope that passes over a frictionless pulley, as shown. At this moment, the system is at rest. Compare the magnitudes of the force of tension exerted on block A and the force of tension exerted on block B.

The force of tension exerted on block A is equal in magnitude to the force of tension exerted on block B.

Blocks A and B have equal masses and are connected by a rope that passes over a frictionless pulley, as shown. At this moment, the system is in motion, with block B moving downward and A moving upward at a constant speed. Compare the magnitudes of the force of tension exerted on block A and the force of tension exerted on block B.

The force of tension exerted on block A is equal in magnitude to the force of tension exerted on block B.

Stephanie pulls on a rope that is attached to a large crate. She is pulling the crate along at a constant speed as it slides across rough carpet. How does the magnitude of the force of tension exerted on Stephanie compare to the magnitude of the force of tension exerted on the crate?

The force of tension exerted on the crate has the same magnitude as the force of tension exerted on Stephanie.

Which of the following is a valid force that could be exerted on a baseball?

The force on a baseball being hit by a bat

In the figure, a hand is pushing on block B to the right, causing both blocks to move to the right across a rough surface at a constant speed. Compare the force that pushes block B to the right to the force that pushes block A to the right.

The force that pushes block A to the right is smaller than the force that pushes block B to the right.

When helping a friend move into a new home, you push a chair across the room. What do you know about the force that you exert on the chair?

The force you exert on the chair contributes to the overall change in kinetic energy of the system (the chair) with a positive amount and therefore does positive work on the system.

When helping a friend move into a new home, you push a chair across the room. What do you know about the force of friction applied to the chair by the floor?

The frictional force applied to the chair contributes to the overall change in kinetic energy of the system (the chair) with a negative amount and therefore does negative work on the system.

A block slides along a rough surface and comes to a stop. What can you conclude about the frictional force exerted on the block?

The frictional force does negative work on the block and decreases its kinetic energy.

An object rests on a ramp that is angled at 20º above the horizontal. What direction (relative to the vertical) will the force of gravity point?

The gravitational force will be directed exactly downward, along the vertical.

Newton's law of universal gravitation states that the force of gravity between you and the Earth gets smaller when you get further away from the center of the Earth. Why is it that we use the same acceleration due to gravity (g = 9.8 m/s2) for all physics problems without paying attention to whether the problem takes place at sea level or at the top of a tall mountain?

The height of a tall mountain is a tiny amount when compared to the radius of the Earth. So even going to the top of a tall mountain barely changes your distance to the center of the Earth.

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.

On a clear night you look up at the Moon overhead. At that moment the Moon is pulling on you via gravity with a certain amount of force, . Considering only magnitudes, how does the force you exert on the Moon via gravity compare to ?

The magnitude of the force you exert on the Moon is equal to Fmoon

Objects A and B are near each other in space and isolated from all other influences. Object A has a mass of 6m while object B has a mass of 2m. How does the magnitude of the net force on each object compare?

The magnitude of the net force on each object is the same.

Blocks A and B are connected by rope 1 and are pulled across a rough surface by rope 2, which is attached to block B, as shown. The applied force is strong enough to make the blocks speed up. Compare the magnitude of the tensions in ropes 1 and 2.

The magnitude of the tensions in the two ropes will not be equal.

Blocks A and B are connected by rope 1 and are pulled at constant speed across a rough surface by rope 2, which is attached to block B, as shown. Compare the magnitude of the tensions in ropes 1 and 2.

The magnitude of the tensions in the two ropes will not be equal.

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 less than the mechanical energy of the block-Earth system at point 1.

If you could somehow increase the mass of an object, what would happen to the net force on the object?

The net force on an object doesn't depend on the object's mass.

You are standing in an elevator as it starts to move downward, accelerating for a moment. Which of these is true at that moment?

The net force on you changes from zero to downward as the elevator begins accelerating.

Which of the following is a legitimate way to describe the force between a road and a car driving on the road?

The normal force exerted by the road on the car

Consider a car driving at a constant speed on a level road. Which of the following is an action-reaction pair (from Newton's third law)?

The normal force exerted on the car by the road and the downward force exerted on the road by the car.

Consider a car speeding up as it drives along a level road. Which of the following is an action-reaction pair (from Newton's third law)?

The normal force exerted on the car by the road and the downward force exerted on the road by the car.

As you accelerate upward in an elevator, which force exerted on you has the greatest magnitude?

The normal force from the elevator floor pushing up on you

Imagine standing in an elevator that is moving upward. Which of the following is the most complete list of the forces that belong on your free-body diagram (FBD) in that moment?

The normal force on you by the elevator floor and the force of gravity on you by the earth

Imagine a car sitting empty in the parking lot. Which of the following is the most complete list of the forces that belong on a free-body diagram (FBD) of the car?

The normal force on your car by the pavement it rests on and the force of gravity on your car by the earth

An object rests on a ramp that is angled at 20º above the horizontal. What direction (relative to the vertical) will the normal force from the ramp point?

The normal force will be directed 20º to the right of vertical.

This position versus time graph represents the motion of an object moving in a straight line. What is true about the objects motion

The object is at rest

If an objects acceleration vector points in the opposite direction of the instantaneous velocity vector,the they can conclude

The object is slowing down

To define the position of an object in a plan,you need to measure

The object's distance from a reference point and it's angle measured from a reference line

If a planet is orbiting a star, what is the most accurate way to describe the shape of the orbit?

The orbit is shaped like an ellipse.

In both figures, a particle of mass m, is released from rest at a height, h. In figure (a), the particle is dropped straight downward and in figure (b) the particle is released from rest and slides down a ramp with a rough surface. Which particle, the one in figure (a) or (b), will have more kinetic energy at the bottom?

The particle in figure (a) will have more kinetic energy than the particle in figure (b) at the bottom.

In figure (b), a particle of mass m is released from rest at the top of a frictionless ramp of height h and in figure (c), a particle of mass 2m is released from rest at the top of the same frictionless ramp. Which particle, the one in figure (b) or (c), will have more kinetic energy at the bottom?

The particle in figure (c) will have more kinetic energy than the particle in figure (b) at the bottom.

If gravity attracts every object in the universe to every other object in the universe, why don't you feel a gravitational pull on you from other people as you walk past them?

The people walking past you do exert a gravitational force on you, but it is far too small to physically sense.

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 2MgR and the tension in the string increases by more than 2Mg .

The work done by the force is equal to the area under the force versus position function.

The potential energy in the spring increases because the spring does negative work on the block.

Allison pulls her little brother, Brody, in a sled on a snow-covered path at a constant speed. Which of the following is an action-reaction pair (from Newton's third law)?

The pulling force that Allison exerts on the sled and the pulling force that the sled exerts on Allison.

A ball is dropped off of a tall building and falls for 2 seconds before landing on a balcony. A rock is then dropped from the top of the building and falls for 4 seconds before landing on the ground. How does the final speed (meaning the speed it had just before landing) of the rock compare to the final speed of the ball?

The rock's final speed is twice as much as the ball's final speed.

A skateboarder is rolling to the right and there are equal time increments between frames. How is the skateboarder moving?

The skateboarder is moving at a constant speed

A block of mass m is attached to a horizontal spring and rests on a flat, smooth surface as seen in the figure. If you push on the block in the negative x-direction and compress the spring, what is true about the work done by the spring on the block during this motion?

The spring does negative work on the block because the spring force is in the opposite direction of the block's displacement.

A block of mass m is attached to a horizontal spring and rests on a flat, smooth surface as seen in the figure. The block can be pushed in the negative x-direction to compress the spring or pulled in the positive x-direction to stretch the spring. Where along the x-axis does the block have to be for the spring to have zero potential energy?

The spring has zero potential energy when the block is at x = 0, where the spring is neither stretched nor compressed.

A 5 kg object near Earth's surface is released from rest such that it falls a distance of 10 m. After the object falls 10 m, it has a speed of 12 m/s. Which of the 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 nonzero

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

What is true about the work done by a conservative force?

The work done by a conservative force is always path independent.

What is true about the work done by a non-conservative force?

The work done by a non-conservative force will always change the total mechanical energy of a system

The graph shows the x-component of a force applied to an object versus the position of that object in the x-direction. How is the work done by this force determined from the data in this graph?

The work done by the force is equal to the area under the force versus position function.

When you lift a book upward off of a table, what is true about the work done on the book by the force of gravity?

The work done by the force of gravity is negative and proportional to the upward displacement of the book.

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 net 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.

You are about to check out at the grocery store and you put a box of cereal on the conveyer belt at the register. The cashier turns on the conveyor belt, causing the box of cereal to speed up momentarily. At this moment, what can we say about the frictional force acting on the box of cereal?

There is a static frictional force pointing in the box's direction of motion, parallel to the conveyer belt.

Somewhere in the universe an object is moving in a slow arcing turn without changing its speed. From just this information, what can we say about the net force on that object?

There must be a net force on the object.

You observe two identical balls of putty heading directly toward each other at equal speeds. What can you say about their total kinetic energy?

They have twice the kinetic energy of either ball by itself.

Exoplanets (planets outside our solar system) are an active area of modern research. Suppose you read an article stating that there is a newly discovered planetary system with three planets. The article states that the outermost planet (Planet C) goes all the way around its star in less time than the innermost planet (Planet A). According to Kepler's laws of planetary motion, is this possible?

This is not possible, since it would violate Kepler's third law of planetary motion.

In which of these processes is the total energy of the system conserved?

Two balls of putty (the system) collide in midair and stick together.

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 v0 from point A along a horizontal surface of negligible friction. It then slides up a ramp, where friction is not negligible, that is inclined at angle θ with respect to the horizontal, as shown in the figure. The student measures the maximum vertical 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 v0 for each trial. The results from the trials are displayed in the table. 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 12mv2initial=mgyfinal to solve for yf .

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 v0 from point A along a horizontal surface of negligible friction. It then slides up a ramp, where friction is not negligible, that is inclined at angle θ with respect to the horizontal, as shown in the figure. The student measures the maximum vertical 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 v0 for each trial. The results from the trials are displayed in the table. How should the student use the data collected and the known quantities from the experiment to determine the 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.

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 D . 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.

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=1/2mΔv^2 with v0 equal to the speed of the object at 0s and vf equal to the speed of the object at 5s .

Which of these equations is the correct mathematical representation of this velocity versus time graph

V=Vi+at

Which of the following is an important difference between an object's mass and its weight?

Weight is determined by the environment of an object, while mass is a fixed property of the object.

Under which circumstance is a force exerted on an apple by your hand?

When the apple is at rest in your open hand

Under which circumstance is there a force exerted on your hand by the apple?

When the apple is at rest in your open hand

A variety of forces are applied to an object such that the net force does positive work on that object. What can you conclude about the speed of the object?

When the total work done on the object is positive, the object's speed will increase.

Under which circumstance is there a force exerted on the apple by your hand?

When you are picking the apple up off of the floor

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

If you kick a big rock very hard while on the Earth, you might break a toe. If you kicked a similar rock while on the Moon, would you still be in danger of breaking your toe?

Yes, this is about the rock's mass, which is the same on the Moon as on the Earth.

Floating in deep space, you find yourself at rest next to a small asteroid. You reach out and tap the asteroid with a hammer. What happens to you in this process?

You will briefly accelerate away from the asteroid and then drift away at a constant speed.

According to Kepler's third law of planetary motion, if the Earth's orbit was twice as large as it is, how long would it take for the Earth to go around the Sun once?

about 2.8 times as long

A person is standing still while leaning against the wall in a classroom. Which is the best answer regarding the number of forces exerted on her?

at least four

In order to state the force exerted on one object by another object, you must give .

both the magnitude of the force and the direction of the force

In general, when a car is driving along a straight road, the force of friction between a car tire and the road _____________.

can point either forward or backward, depending on what the car is doing.

Newtons and pounds are __________.

different units for measuring force

Which of the following forces is considered a conservative force?

gravity

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 M2 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 person is trying to pull a heavy crate across a room with a rope that is attached to the crate, but it doesn't move. The tension in the rope ________________.

is equal at both ends of the rope

The mass of an object ______.

is not a vector and has no direction.

The force exerted by our Sun on the planets in our solar system ______.

is proportional to the mass of the sun

Consider a car at rest, parked on level ground. The force of friction between a car tire and the ground _____________________.

is zero

In general, when a planet orbits a star, ______.

it moves with a higher speed during some parts of its orbit and a slower speed during other parts.

Currently, the Moon takes 27.3 days to go around the Earth. Suppose a supervillain shifted the Moon into a new, lower, circular orbit. How long would it take for the Moon to go around the Earth in its new circular orbit?

less than 27.3 days

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. A

meterstick and force sensor

The mechanical energy of a system is conserved during a certain process only if __________.

non-conservative forces do zero total work on the system during that process

Kepler's second law of planetary motion describes the area "swept out" by the line connecting a planet and the Sun during equal time intervals. The conceptual message of the law is that ______.

planets move faster when they are near the Sun, and move more slowly when they are farther away.

An object's mass and weight are _____.

proportional to each other.

If Quantity X is conserved for a certain system and during a certain process, that means__________.

quantity X for that system does not change in any way during that process

Exoplanets (planets outside our solar system) are an active area of modern research. Suppose astronomers find such a planet that has the same mass as Earth, but has a radius that is about 10% less. Roughly, what acceleration due to gravity would you expect if you were standing on the surface of this new planet?

roughly 12 m/s^2

Exoplanets (planets outside our solar system) are an active area of modern research. Suppose astronomers find such a planet that has the same radius as Earth, but is about 10% less massive. Roughly, what acceleration due to gravity would you expect if you were standing on the surface of this new planet?

roughly 9 m/s^2

A box rests on a table. The normal force exerted by the table on the box is equal in magnitude to the weight of the box and points in the opposite direction. This is because ________________.

the net force on the box is zero and, therefore, the forces must be balanced

If an object's acceleration vector points in the same direction as its instantaneous velocity vector then you can conclude __________.

the object is speeding up

Newtons and kilograms are __________.

units for different quantities, and cannot be converted to each other

Which of these equations is the correct mathematical representation of this position versus time graph?

x=xi + vt