AP Physics 1 Quiz: Elastic And Inelastic Collisions
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Elastic And Inelastic CollisionsQuestion 1 of 20

A moving cart collides with a stationary cart on a nearly frictionless track. After the collision, the carts move together as a single unit. What can be concluded about kinetic energy in the collision?

It must be conserved because momentum is conserved.
It must decrease because the collision is perfectly inelastic.
It must increase because the carts combine masses.
It becomes zero because the carts stick together.
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AP Physics 1 Quiz

AP Physics 1 Quiz: Elastic And Inelastic Collisions

Practice Elastic And Inelastic Collisions in AP Physics 1 with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.

What this quiz covers

This quiz focuses on Elastic And Inelastic Collisions, giving you a quick way to practice the rules, question types, and explanations that matter most for AP Physics 1.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

All questions

Question 1

A moving cart collides with a stationary cart on a nearly frictionless track. After the collision, the carts move together as a single unit. What can be concluded about kinetic energy in the collision?

  1. It must be conserved because momentum is conserved.
  2. It must decrease because the collision is perfectly inelastic. (correct answer)
  3. It must increase because the carts combine masses.
  4. It becomes zero because the carts stick together.

Explanation: This question probes the behavior of kinetic energy in elastic versus inelastic collisions. Momentum is conserved in all isolated collisions without external forces. Elastic collisions maintain both momentum and total kinetic energy. Inelastic collisions, especially perfectly inelastic ones where objects merge, conserve momentum but result in kinetic energy loss. Choice A is a distractor, incorrectly linking KE conservation directly to momentum without considering collision type. A transferable strategy is to recognize sticking as a sign of perfectly inelastic collisions and expect KE reduction accordingly.

Question 2

A 0.40 kg0.40\,\text{kg} cart moving right at 3.0 m/s3.0\,\text{m/s} collides with a 0.40 kg0.40\,\text{kg} cart initially at rest on a level track. After the collision, the carts stick together and move as one. Which statement about this collision is correct?

  1. Both momentum and kinetic energy are conserved because the track is level.
  2. Momentum is conserved, but kinetic energy is not conserved because the carts stick together. (correct answer)
  3. Kinetic energy is conserved, but momentum is not conserved because the carts stick together.
  4. Neither momentum nor kinetic energy is conserved because the carts stick together.

Explanation: This question tests understanding of elastic and inelastic collisions. In all collisions between objects in an isolated system, momentum is conserved due to Newton's third law - the internal forces between objects are equal and opposite, so the total momentum remains constant. However, kinetic energy is only conserved in elastic collisions where objects bounce apart without permanent deformation. In this collision, the carts stick together, which is the defining characteristic of a perfectly inelastic collision where kinetic energy is lost to deformation, sound, and heat. Choice A incorrectly claims both are conserved, ignoring that sticking indicates energy loss. When objects stick together after collision, remember that momentum is still conserved but kinetic energy is always lost.

Question 3

A 0.50 kg0.50\,\text{kg} cart moving right collides with a 1.0 kg1.0\,\text{kg} cart initially at rest on a low-friction track. The carts bounce apart and do not stick. Which additional information is needed to decide whether kinetic energy is conserved?

  1. Whether the carts experience equal and opposite forces during the collision.
  2. The carts' velocities after the collision. (correct answer)
  3. The carts' masses before the collision.
  4. Whether momentum is conserved during the collision.

Explanation: This question tests understanding of elastic and inelastic collisions. To determine whether a collision is elastic (kinetic energy conserved) or inelastic (kinetic energy not conserved), we need to compare the total kinetic energy before and after the collision. We already know the masses and initial velocities, so we can calculate the initial kinetic energy. However, to calculate the final kinetic energy, we need the final velocities of both carts after they bounce apart. Choice A incorrectly assumes rebounding guarantees elasticity, while choices C and D ask for information we already have or that's always true. The key strategy is to calculate kinetic energy using KE = ½mv² for each object before and after collision - if the totals match, it's elastic.

Question 4

Cart AA collides with cart BB on a frictionless track. The collision is described as elastic. Immediately after, the carts separate and the total kinetic energy of the two-cart system is unchanged.

Which statement is correct for the two-cart system?

  1. Momentum is conserved only if the carts have equal mass.
  2. Momentum is not conserved because the carts exert forces on each other.
  3. Both momentum and kinetic energy are conserved. (correct answer)
  4. Only kinetic energy is conserved in an elastic collision.

Explanation: This question evaluates the definition and implications of elastic collisions in AP Physics 1. Conservation of momentum applies to all isolated collisions, elastic or inelastic, due to balanced internal forces. Elastic collisions uniquely conserve kinetic energy as well, with total KE unchanged post-collision. Inelastic collisions do not conserve KE, even if objects separate. Choice D mistakenly states that only kinetic energy is conserved in elastic collisions, overlooking that momentum is also always conserved. A transferable strategy is to verify elasticity by confirming unchanged total KE and apply both conservation laws simultaneously for elastic problems.

Question 5

A moving cart collides with a stationary cart on a frictionless track. After the collision, the two carts move together with a smaller speed than the original cart had. The collision is stated to be perfectly inelastic.

Which conclusion is correct?

  1. Total momentum is conserved, and total kinetic energy decreases. (correct answer)
  2. Total kinetic energy is conserved, and total momentum decreases.
  3. Both total momentum and total kinetic energy are conserved.
  4. Total momentum becomes zero because the carts stick together.

Explanation: This question examines conservation principles in perfectly inelastic collisions in AP Physics 1. Momentum conservation holds in both elastic and inelastic collisions for isolated systems, ensuring the total momentum remains constant. Elastic collisions preserve kinetic energy, with no loss to other forms. Inelastic collisions, particularly perfectly inelastic ones where objects stick, result in kinetic energy decrease while momentum is conserved. Choice D erroneously states that momentum becomes zero when carts stick, but momentum is conserved and depends on initial conditions, not zero unless initially zero. A transferable strategy is to calculate post-collision velocity using momentum conservation and compare kinetic energies to confirm loss in inelastic cases.

Question 6

A rubber ball rolls right and collides head-on with a cart initially at rest on a low-friction track. The ball bounces back to the left after the collision. External forces are negligible.

What can be concluded about kinetic energy conservation?

  1. Kinetic energy must be conserved because the ball reverses direction.
  2. Kinetic energy may or may not be conserved; more information is needed. (correct answer)
  3. Kinetic energy cannot be conserved because momentum is always lost in collisions.
  4. Kinetic energy must decrease because the cart was initially at rest.

Explanation: This question assesses uncertainty in kinetic energy conservation for collisions in AP Physics 1. Momentum is always conserved in isolated collisions, but kinetic energy conservation distinguishes elastic from inelastic types. In elastic collisions, both quantities are conserved, often with objects rebounding. In inelastic collisions, kinetic energy decreases, though rebounding can still occur depending on masses and velocities. Choice A wrongly claims kinetic energy must be conserved due to direction reversal, but reversal can happen in inelastic cases without KE conservation. A transferable strategy is to gather data on masses and velocities to calculate both momentum and KE before and after, determining the collision type empirically.

Question 7

Two identical pucks collide on nearly frictionless ice. Before the collision, puck 1 moves right and puck 2 is at rest. After the collision, puck 1 stops and puck 2 moves right with the same speed puck 1 initially had. Assume external forces are negligible.

What type of collision is most consistent with these observations?

  1. Elastic, because kinetic energy is conserved in addition to momentum. (correct answer)
  2. Perfectly inelastic, because one object stops after impact.
  3. Inelastic, because momentum is not conserved in collisions.
  4. Inelastic, because kinetic energy is always conserved in collisions.

Explanation: This question evaluates the distinction between elastic and inelastic collisions in AP Physics 1. In isolated systems, momentum is conserved in both elastic and inelastic collisions due to Newton's third law and no external forces. Elastic collisions conserve both momentum and kinetic energy, often resulting in objects bouncing apart with unchanged total KE. Inelastic collisions conserve momentum but not kinetic energy, with objects possibly sticking or separating but with energy loss. For instance, choice B wrongly labels it perfectly inelastic because one object stops, but perfectly inelastic requires sticking together, not separation. A transferable strategy is to check if initial and final kinetic energies match to confirm elasticity, especially for equal-mass head-on collisions where velocities exchange.

Question 8

Two carts on a frictionless track collide and stick. Before the collision, cart AA moves right and cart BB moves right more slowly. Afterward, they move together to the right. External forces are negligible.

Which statement best describes the system during the collision?

  1. Momentum is not conserved because both carts were moving before impact.
  2. Kinetic energy is conserved because both carts move in the same direction.
  3. Momentum is conserved, but kinetic energy is not conserved. (correct answer)
  4. Both momentum and kinetic energy are not conserved because they stick.

Explanation: This question probes the application of conservation laws to inelastic collisions in AP Physics 1. In any collision without external forces, momentum is conserved for the system, reflecting the internal nature of interaction forces. Elastic collisions additionally conserve kinetic energy, keeping the total unchanged. Inelastic collisions conserve momentum but not kinetic energy, especially when objects stick together after colliding. Choice A incorrectly asserts that momentum is not conserved because both were moving, but conservation applies regardless of initial motions in isolated systems. A transferable strategy is to treat the system as isolated and use vector momentum for direction-dependent collisions, while checking for KE conservation separately.

Question 9

A moving cart collides with an identical cart at rest on a nearly frictionless track. Afterward, the two carts move together as one object. Which conclusion about energy and momentum is most accurate?

  1. Momentum is conserved, but kinetic energy is not conserved. (correct answer)
  2. Kinetic energy is conserved, but momentum is not conserved.
  3. Both momentum and kinetic energy are conserved because the carts are identical.
  4. Objects sticking together implies the final momentum is zero.

Explanation: This question tests understanding of elastic and inelastic collisions. When two objects collide and stick together, this is a perfectly inelastic collision - the most inelastic type possible. In all collisions of isolated systems, momentum is conserved because the forces between objects are internal and cancel out according to Newton's third law. However, kinetic energy is not conserved in inelastic collisions; some energy is transformed into heat, sound, and permanent deformation as the objects merge. Choice C incorrectly assumes identical masses guarantee energy conservation, while choice D wrongly claims sticking implies zero final momentum. Remember that objects sticking together is the hallmark of a perfectly inelastic collision where maximum kinetic energy is lost while momentum remains conserved.

Question 10

A rubber ball cart collides head-on with another cart on a low-friction track; afterward, the system's kinetic energy is unchanged. Which is correct?​

  1. Elastic collision: momentum and kinetic energy are conserved for the two-cart system. (correct answer)
  2. Inelastic collision: momentum is not conserved because the carts separate.
  3. Perfectly inelastic collision: kinetic energy is conserved because they bounce.
  4. Collision type cannot be determined because kinetic energy is always conserved.

Explanation: This question tests understanding of elastic and inelastic collisions. When the system's total kinetic energy remains unchanged after a collision, this defines an elastic collision. In elastic collisions, both momentum and kinetic energy are conserved for the isolated system. The rubber ball cart likely has elastic properties that allow it to bounce without permanent deformation or energy loss. Choice C incorrectly calls this perfectly inelastic while claiming kinetic energy is conserved, but perfectly inelastic collisions always lose kinetic energy. To identify collision types, check kinetic energy: unchanged means elastic, decreased means inelastic, and maximum loss with sticking means perfectly inelastic.

Question 11

On a frictionless track, cart AA moves right and collides head-on with cart BB at rest. After the collision, the carts stick together and move right as one. Which statement about the collision is correct?

Which quantity is conserved during the collision?

  1. Only kinetic energy is conserved because the carts stick together.
  2. Neither momentum nor kinetic energy is conserved because the carts stick together.
  3. Only momentum is conserved; kinetic energy is not conserved. (correct answer)
  4. Momentum is not conserved because cart BB was initially at rest.

Explanation: This question assesses the understanding of conservation laws in elastic and inelastic collisions in AP Physics 1. In all isolated collisions where external forces are negligible, linear momentum is always conserved because the system is closed. In elastic collisions, both momentum and kinetic energy are conserved, with the total kinetic energy remaining the same before and after. In inelastic collisions, such as when objects stick together, momentum is conserved, but kinetic energy is not, as some is lost to other forms like heat or sound. For example, choice A incorrectly claims that only kinetic energy is conserved because the carts stick together, ignoring that kinetic energy decreases in inelastic collisions. A transferable strategy is to identify if objects stick together to classify the collision as inelastic and apply conservation of momentum while noting kinetic energy loss.

Question 12

A glider moving right collides with an identical glider at rest on an air track. After the collision, the two gliders stick and slide together. External forces are negligible.

Which statement about the system is correct?

  1. Momentum is conserved, but kinetic energy is not conserved. (correct answer)
  2. Kinetic energy is conserved, but momentum is not conserved.
  3. Both momentum and kinetic energy are conserved because the gliders are identical.
  4. Momentum becomes zero after sticking because they form one object.

Explanation: This question examines conservation in perfectly inelastic collisions with identical masses in AP Physics 1. In isolated systems, momentum conservation holds for elastic and inelastic collisions alike. Elastic collisions conserve both momentum and kinetic energy. Inelastic collisions, such as when gliders stick, conserve momentum but lose kinetic energy to deformation or heat. Choice D falsely claims momentum becomes zero after sticking, but the combined momentum equals the initial, halved for identical masses with one at rest. A transferable strategy is to use the sticking condition to treat post-collision as a single mass and solve for velocity via momentum, then compute KE difference.

Question 13

Two carts collide on a frictionless track. After the collision, they move apart, and the total kinetic energy of the system is measured to be smaller than before. External forces are negligible.

Which classification is consistent with the measurement?

  1. Elastic, because momentum conservation implies kinetic energy conservation.
  2. Inelastic, because kinetic energy is not conserved. (correct answer)
  3. Perfectly inelastic, because they moved apart after the collision.
  4. Elastic, because kinetic energy decreases in elastic collisions.

Explanation: This question tests classification based on energy measurements in collisions for AP Physics 1. Momentum is conserved in both elastic and inelastic collisions when the system is isolated. Elastic collisions conserve kinetic energy, resulting in no net loss. Inelastic collisions feature kinetic energy loss, even if objects move apart after impact. Choice D incorrectly suggests that kinetic energy decreases in elastic collisions, but by definition, it remains constant in elastic ones. A transferable strategy is to measure pre- and post-collision KE; if it decreases but objects separate, classify as inelastic and use momentum for velocity calculations.

Question 14

Two carts on a frictionless track collide and stick together. The combined cart continues moving in the same direction as cart AA was initially moving. External forces are negligible.

Which statement best distinguishes this collision from an elastic collision?

  1. In this collision, momentum is not conserved, unlike an elastic collision.
  2. In this collision, kinetic energy is not conserved, unlike an elastic collision. (correct answer)
  3. In this collision, objects stick so the system's momentum must be zero afterward.
  4. In this collision, kinetic energy is conserved but momentum is not conserved.

Explanation: This question distinguishes inelastic from elastic collisions in AP Physics 1. Momentum is conserved in all types of isolated collisions, but kinetic energy conservation is specific to elastic ones. In elastic collisions, both momentum and KE are preserved, often with separation. Inelastic collisions, especially those where objects stick, do not conserve KE, though momentum remains constant. Choice A wrongly states that momentum is not conserved in this inelastic case, but momentum conservation is universal in isolated systems. A transferable strategy is to compare collision types by checking KE conservation; if lost, it's inelastic, and apply momentum to find final velocities regardless.

Question 15

Cart AA moving right collides with cart BB moving left on a level track. The carts bounce apart, and afterward each cart reverses direction (they separate, not stick). External forces are negligible.

Which statement must be true about momentum and kinetic energy?

  1. Momentum is conserved only if the collision is elastic.
  2. Momentum is conserved, but kinetic energy may or may not be conserved. (correct answer)
  3. Kinetic energy is conserved because the carts bounce apart.
  4. Neither momentum nor kinetic energy is conserved because directions changed.

Explanation: This question tests knowledge of conserved quantities in collisions for AP Physics 1. Momentum is conserved in all collisions within isolated systems, regardless of whether they are elastic or inelastic, as long as no external forces act. In elastic collisions, kinetic energy is also conserved, maintaining the same total KE before and after the interaction. In inelastic collisions, kinetic energy is not conserved, even if objects bounce apart, due to energy dissipation. Choice C mistakenly assumes kinetic energy is always conserved when carts bounce, but bouncing can occur in inelastic collisions with KE loss. A transferable strategy is to always apply momentum conservation first and then assess kinetic energy based on whether the collision is specified as elastic or if energies match.

Question 16

On a frictionless track, cart AA (mass mm) moving right collides head-on with cart BB (mass mm) at rest. After the collision, the carts latch together and move as one. Which statement about conservation laws during the collision is correct?

  1. Both momentum and kinetic energy are conserved because the track is frictionless.
  2. Momentum is conserved, but kinetic energy is not conserved because the collision is perfectly inelastic. (correct answer)
  3. Kinetic energy is conserved, but momentum is not conserved because the carts stick together.
  4. Neither momentum nor kinetic energy is conserved because the carts change speed.

Explanation: This question assesses the understanding of conservation laws in elastic and inelastic collisions. In all collisions within an isolated system, linear momentum is conserved if no external net force acts on the system. In elastic collisions, both momentum and kinetic energy are conserved, with the total kinetic energy remaining the same before and after. In inelastic collisions, particularly perfectly inelastic ones where objects stick together, momentum is conserved, but kinetic energy decreases as it is transformed into other forms like heat or deformation. A common distractor is choice A, which incorrectly assumes that a frictionless track guarantees kinetic energy conservation, overlooking that the type of collision determines KE conservation. To analyze collisions effectively, always determine if the system is isolated for momentum conservation and check if objects stick together to identify perfectly inelastic cases.

Question 17

Two objects collide in one dimension on a frictionless surface. Afterward, they stick together and slide with a constant nonzero speed. Which statement must be true about the system during the collision?

  1. The system's kinetic energy is conserved because the final speed is constant.
  2. The system's momentum is conserved, but some kinetic energy is transformed to other forms. (correct answer)
  3. The system's momentum becomes zero because the objects are stuck together.
  4. Momentum is not conserved in inelastic collisions, only in elastic collisions.

Explanation: This question tests understanding of elastic and inelastic collisions. When objects stick together after collision, this represents a perfectly inelastic collision where maximum kinetic energy loss occurs. In any collision of an isolated system on a frictionless surface, momentum must be conserved because the collision forces are internal and cancel according to Newton's third law. However, kinetic energy is not conserved in inelastic collisions - some energy transforms into heat, sound, and permanent deformation as the objects merge. Choice A wrongly equates constant final speed with energy conservation, while choice D incorrectly claims momentum isn't conserved in inelastic collisions. Remember that sticking together is the defining feature of perfectly inelastic collisions: momentum stays constant but kinetic energy decreases.

Question 18

A cart collides with a second cart at rest on a low-friction track. The carts separate after impact, and measurements show total kinetic energy after is less than before. What type of collision occurred?

  1. Elastic, because the carts did not stick together.
  2. Perfectly inelastic, because kinetic energy decreased.
  3. Inelastic (but not perfectly inelastic), because kinetic energy decreased while the carts did not stick. (correct answer)
  4. Elastic, because momentum is conserved in all collisions.

Explanation: This question tests understanding of elastic and inelastic collisions. Collisions are classified by whether kinetic energy is conserved: elastic collisions conserve both momentum and kinetic energy, while inelastic collisions conserve only momentum. When kinetic energy decreases but objects don't stick together, this is an inelastic collision that isn't perfectly inelastic - some energy is lost to heat, sound, and temporary deformation, but the objects retain separate identities. A perfectly inelastic collision specifically requires objects to stick together, resulting in maximum kinetic energy loss. Choice A incorrectly assumes not sticking means elastic, while choice D wrongly claims momentum conservation implies elasticity. To classify collisions, check both whether objects stick (perfectly inelastic) and whether kinetic energy is conserved (elastic) or lost (inelastic).

Question 19

A 1.0 kg1.0\,\text{kg} cart moving right collides with a 1.0 kg1.0\,\text{kg} cart initially at rest. After the collision, the first cart stops and the second moves right. Which statement best classifies the collision?

  1. Perfectly inelastic, because one cart stops.
  2. Inelastic, because momentum is not conserved when carts exchange motion.
  3. Elastic, because this outcome is consistent with kinetic energy conservation in a head-on collision of equal masses. (correct answer)
  4. Inelastic, because kinetic energy is conserved in all collisions.

Explanation: This question tests understanding of elastic and inelastic collisions. When two objects of equal mass collide head-on with one initially at rest, and afterward the moving object stops while the stationary object moves with the original velocity, this is a characteristic outcome of an elastic collision. In elastic collisions, both momentum and kinetic energy are conserved - the total kinetic energy before equals the total kinetic energy after. This specific scenario (complete velocity exchange for equal masses) only occurs in elastic collisions where no energy is lost to heat, sound, or deformation. Choice A wrongly assumes stopping means perfectly inelastic, while choice B incorrectly claims momentum isn't conserved. For equal-mass collisions where velocities completely exchange, the collision must be elastic to conserve both momentum and kinetic energy.

Question 20

A 0.30 kg0.30\,\text{kg} cart moving right at 2.0 m/s2.0\,\text{m/s} collides with a 0.30 kg0.30\,\text{kg} cart at rest. After the collision, both carts move right together. Which statement distinguishes momentum from kinetic energy conservation here?

  1. Momentum is conserved only if kinetic energy is conserved.
  2. Momentum is conserved in this isolated collision, but kinetic energy decreases in a perfectly inelastic collision. (correct answer)
  3. Kinetic energy is conserved because the carts move together after the collision.
  4. Momentum is not conserved because the carts stick together.

Explanation: This question tests understanding of elastic and inelastic collisions. When objects stick together after collision, this is a perfectly inelastic collision - the most extreme form where maximum kinetic energy is lost. Momentum is always conserved in isolated collisions because internal forces between objects cancel according to Newton's third law, so the total momentum before equals the total momentum after. However, kinetic energy decreases in perfectly inelastic collisions as energy transforms into heat, sound, and permanent deformation during the sticking process. Choice C incorrectly claims moving together conserves energy, while choice D wrongly states sticking violates momentum conservation. The key distinction is that momentum conservation is universal for isolated systems, but kinetic energy is only conserved in elastic collisions where objects bounce without sticking.