AP Physics 1 Scoring Guide
Unit 5 Progress Check: FRQ

  Page 1 of 13
1. This question is a long free-response question. Show your work for each part of the question.
 A solid block of mass may be placed at different locations along a curved ramp. At the
 bottom of the ramp is a solid block of mass that is at rest on a horizontal surface. Figure
 1 shows both blocks before block is released. A group of students must graphically
 determine the relationship between the release height of block and the speed at which the
 two-block system travels after the blocks collide and stick together. Figure 2 shows both blocks
 after the collision. Frictional forces between block and the ramp and between both blocks
 and the horizontal surface are considered to be negligible.
 (a)
 i. State the basic physics principles, laws, or equations that students could use to graphically
 determine the relationship between the release height of block and the speed at which the
 two-block system travels after the blocks collide and stick together.
 AP Physics 1 Scoring Guide
Unit 5 Progress Check: FRQ

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Please respond on separate paper, following directions from your teacher.
 ii. Derive an equation that relates the initial release height of block and the speed of
 the two-block system after the collision in terms of , , and fundamental constants, as
 appropriate.
 Please respond on separate paper, following directions from your teacher.
 (b) Design an experimental procedure the students could use to graphically determine the
 relationship between the release height of block and the speed at which the two-block
 system travels after the blocks collide and stick together.
 In the table below, list the quantities and associated symbols that would be measured in your
 experiment and the equipment used to measure them. Also list the equipment that would be
 used to measure each quantity. You do not need to fill in every row. If you need additional
 rows, you may add them to the space just below the table.

Describe the overall procedure to be used, referring to the table. Provide enough detail so that
 another student could replicate the experiment, including any steps necessary to reduce
 experimental uncertainty.
 Please respond on separate paper, following directions from your teacher.
 AP Physics 1 Scoring Guide
Unit 5 Progress Check: FRQ

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conducted, the students observe that the blocks do not stick together, as shown in Figure 4.
 The students predict the speed of block after the collision by assuming that the collision is
 perfectly elastic. They then collect data about the actual speeds of both blocks immediately
 after the collision, as shown in the table.
 (c) Why does the predicted speed of block after the collision not agree with the actual speed
 of block after the collision?
 AP Physics 1 Scoring Guide
Unit 5 Progress Check: FRQ

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Please respond on separate paper, following directions from your teacher.
Part (a)i
Select a point value to view scoring criteria, solutions, and/or examples and to score the response.

Student response accurately includes both of the following criteria.
 1 point is earned for stating that the conservation of energy should be applied to this situation.
 1 point is earned for stating that the conservation of momentum should be applied to this
 situation.
Example Response:
Students will need to use both conservation of momentum (for the collision) and conservation of energy
 (for the slide down the ramp) to be able to determine the relationship between the release height of block
 X and the speed at which the two-block system travels after they collide and stick together.
Part (a)ii
Select a point value to view scoring criteria, solutions, and/or examples and to score the response.

Student response accurately includes all of the following criteria.
 1 point is earned for a correct application of the conservation of momentum for an inelastic
 AP Physics 1 Scoring Guide
Unit 5 Progress Check: FRQ

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collision.
 1 point is earned for explicitly or implicitly stating that the change in the gravitational potential
 energy of the block X-Earth system at the release height is converted into the kinetic energy of
 block Xat the bottom of the ramp.
 1 point is earned for recognizing that the initial velocity of immediately before the collision
 is .
 Example Response:
Part (b)
Select a point value to view scoring criteria, solutions, and/or examples and to score the response.

Student response accurately includes all of the following criteria.
 AP Physics 1 Scoring Guide
Unit 5 Progress Check: FRQ

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1 point is earned for listing relevant/appropriate equipment that matches the measured
 quantities.
 1 point is earned for measuring the mass of both block X and block Y with an appropriate
 measuring device.
 1 point is earned for measuring the vertical release height of block X with an appropriate
 measuring device.
 1 point is earned for measuring the speed of the two block system immediately after the
 collision with an appropriate measuring device or an appropriate procedure that includes
 measurements of distance and time for the system.
 1 point is earned for attempting to reduce uncertainty (e.g., multiple trials, with some
 parameter either fixed or varied -- e.g. “releasing block X from different vertical heights” -- as
 appropriate).
Example Response:
1. Use an electronic balance to measure the mass of block X and block Y.
 2. Place block Yon the horizontal surface a small distance in front of the bottom of the ramp so that block
 X horizontally collides with block Y.
 3. Place a motion detector in front of block Y so that the two block system will travel toward the motion
 detector immediately after the collision.
 4. Use a meterstick to measure the vertical release height of the center of mass of block X when placed
 on the ramp.
 5. Activate the motion detector and release block X from rest.
 6. Stop collecting data with the motion detector of the two block system travels to the motion detector.
 8. Repeat the experiment for several trials for the release height.
 9. Repeat steps 1-8 for different release heights.
Part (c)
Select a point value to view scoring criteria, solutions, and/or examples and to score the response.
 AP Physics 1 Scoring Guide
Unit 5 Progress Check: FRQ

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Student response accurately includes both of the following criteria.
 1 point is earned for indicating that the collision is not perfectly elastic.
 1 point is earned for indicating a conceptually appropriate reason for why the collision is not
 perfectly elastic.
Example Response:
The collision between block Wand block Z is not perfectly elastic even though the two blocks do not
 remain stuck together. During the collision, the two blocks may have momentarily stuck together or one
 block may have slightly caused a temporary deformation to occur with the surface of the other block.
Part (c)
Select a point value to view scoring criteria, solutions, and/or examples and to score the response.

Student response accurately includes both of the following criteria.
 1 point is earned for indicating that the collision is not perfectly elastic.
 1 point is earned for indicating a conceptually appropriate reason for why the collision is not
 perfectly elastic.
Example Response:
The collision between block Wand block Z is not perfectly elastic even though the two blocks do not
 remain stuck together. During the collision, the two blocks may have momentarily stuck together or one
 AP Physics 1 Scoring Guide
Unit 5 Progress Check: FRQ

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block may have slightly caused a temporary deformation to occur with the surface of the other block.
2. This question is a short free-response question. Show your work for each part of the question.
 A ball is thrown toward the ground. The figure shows the direction of the ball before it reaches
 the ground and the direction of the ball after it bounces off the ground. After the bounce, the
 ball leaves the ground with the same speed that it had before the bounce. The angle between
 the ground and the ball’s direction of travel is before and after the ball bounces off the
 ground. The positive directions are indicated in the figure.
 (a) Each grid below represents a component of the change in momentum of the ball as a result
 of the bounce. On each grid, draw a vector arrow to indicate the direction and relative
 magnitude of the change in momentum of the ball as a result of the bounce. If there is no
 change in momentum for a given component, write “NO CHANGE” under the corresponding
 grid.
 AP Physics 1 Scoring Guide
Unit 5 Progress Check: FRQ

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Please respond on separate paper, following directions from your teacher.
 (b) A ball of mass is released from rest at height above the ground. After the ball
 reaches the ground, it bounces and travels to height above the ground, as shown in the
 figure. In a clear, coherent paragraph-length response that may also contain equations and
 drawings, explain, using the conservation of momentum and the conservation of energy, why
 .
 Please respond on separate paper, following directions from your teacher.
Part (a)
Select a point value to view scoring criteria, solutions, and/or examples and to score the response.

Student response accurately includes both of the following criteria.
 1 point is earned for writing “NO CHANGE” for the horizontal component of the change in
 momentum for the ball.
 AP Physics 1 Scoring Guide
Unit 5 Progress Check: FRQ

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1 point is earned for drawing an upward arrow for the vertical component of the change in
 momentum for the ball.
Example Response:
 Part (b)
Select a point value to view scoring criteria, solutions, and/or examples and to score the response.

Student response accurately includes all of the following criteria.
 1 point is earned for indicating that the collision of the ball with the ground is an inelastic
 collision.
 1 point is earned for indicating that the momentum of the ball immediately before the bounce is
 not the same as the momentum of the ball immediately after the collision.
 1 point is earned for stating that the kinetic energy of the ball immediately before the bounce is
 not the same as the kinetic energy of the ball immediately after the collision.
 1 point is earned for stating that some of the mechanical energy of the ball or the ball-Earth
 AP Physics 1 Scoring Guide
Unit 5 Progress Check: FRQ

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system is converted into nonmechanical energy, which is why the ball has less mechanical
 energy to reach height
 1 point is earned for a logical, relevant, and internally consistent argument that addresses the
 required argument or question asked, and follows the guidelines described in the published
 requirements for the paragraph-length response.
Example Response:
The gravitational potential energy of the ball-Earth system is converted into kinetic energy immediately
 before the ball reaches the ground. During the bounce, mechanical energy of the ball is converted into
 nonmechanical forms of energy, which decreases the kinetic energy of the ball after the bounce occurs.
 This means that the collision is inelastic, and the total momentum of the ball decreases since some of its
 momentum was transferred to the ground. With less kinetic energy, there is not enough mechanical
 energy to convert into gravitational potential energy of the ball-Earth system to reach
 Claims, Evidence, and Reasoning Statements:
 Claim: Height
 Evidence: After the ball reaches the ground, it bounces and travels to height above the ground, as
 shown in the figure, which is not as high off of the ground as height
 Reasoning Statement(s): The gravitational potential energy of the ball-Earth system is converted into
 kinetic energy immediately before the ball reaches the ground. During the bounce, mechanical energy of
 the ball is converted into nonmechanical forms of energy, which decreases the kinetic energy of the ball
 after the bounce occurs. This means that the collision is inelastic, and the total momentum of the ball
 decreases since some of its momentum was transferred to the ground. With less kinetic energy, there is
 not enough mechanical energy to convert into gravitational potential energy of the ball-Earth system to
 reach
Part (b)
Select a point value to view scoring criteria, solutions, and/or examples and to score the response.

AP Physics 1 Scoring Guide
Unit 5 Progress Check: FRQ

  Page 12 of 13
Student response accurately includes all of the following criteria.
 1 point is earned for indicating that the collision of the ball with the ground is an inelastic
 collision.
 1 point is earned for indicating that the momentum of the ball immediately before the bounce is
 not the same as the momentum of the ball immediately after the collision.
 1 point is earned for stating that the kinetic energy of the ball immediately before the bounce is
 not the same as the kinetic energy of the ball immediately after the collision.
 1 point is earned for stating that some of the mechanical energy of the ball or the ball-Earth
 system is converted into nonmechanical energy, which is why the ball has less mechanical
 energy to reach height
 1 point is earned for a logical, relevant, and internally consistent argument that addresses the
 required argument or question asked, and follows the guidelines described in the published
 requirements for the paragraph-length response.
Example Response:
The gravitational potential energy of the ball-Earth system is converted into kinetic energy immediately
 before the ball reaches the ground. During the bounce, mechanical energy of the ball is converted into
 nonmechanical forms of energy, which decreases the kinetic energy of the ball after the bounce occurs.
 This means that the collision is inelastic, and the total momentum of the ball decreases since some of its
 momentum was transferred to the ground. With less kinetic energy, there is not enough mechanical
 energy to convert into gravitational potential energy of the ball-Earth system to reach
 Claims, Evidence, and Reasoning Statements:
 Claim: Height
 Evidence: After the ball reaches the ground, it bounces and travels to height above the ground, as
 shown in the figure, which is not as high off of the ground as height
 Reasoning Statement(s): The gravitational potential energy of the ball-Earth system is converted into
 kinetic energy immediately before the ball reaches the ground. During the bounce, mechanical energy of
 the ball is converted into nonmechanical forms of energy, which decreases the kinetic energy of the ball
 after the bounce occurs. This means that the collision is inelastic, and the total momentum of the ball
 decreases since some of its momentum was transferred to the ground. With less kinetic energy, there is
 not enough mechanical energy to convert into gravitational potential energy of the ball-Earth system to
 AP Physics 1 Scoring Guide
Unit 5 Progress Check: FRQ
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