Practice Collisions in Physics

Use these practice problems to test your method after reviewing the concept explanation and worked examples.

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Quick Recap

A collision is an interaction in which objects exert large forces on each other for a short time, changing their momenta.

During a crash or bounce, forces act briefly but strongly, so motion can change a lot.

Showing a random 20 of 50 problems.

Example 1

medium

0.05 \text{ kg}

bullet at

400 \text{ m/s}

embeds in a

2 \text{ kg}

block at rest on a frictionless surface. Find the block-bullet speed afterward.

Example 2

medium

A 0.15 kg baseball hits a bat at

40\,\text{m/s}

and rebounds at

30\,\text{m/s}

. Find the magnitude of the impulse delivered.

Example 3

hard

0.05 \text{ kg}

bullet at

300 \text{ m/s}

passes through a

2 \text{ kg}

block and exits at

100 \text{ m/s}

. The block sits on a frictionless surface. Find the block's speed afterward.

Example 4

medium

A 1 kg ball at

10\,\text{m/s}

hits a 1 kg ball at rest; afterward they both move at

5\,\text{m/s}

. Is this collision elastic?

Example 5

easy

A 0.5 kg ball changes velocity from

0

6\,\text{m/s}

in a collision. Find the impulse on it.

Example 6

medium

Two carts on a frictionless track:

m_1 = 2 \text{ kg}

+3 \text{ m/s}

m_2 = 1 \text{ kg}

-6 \text{ m/s}

. They stick. Find the final velocity.

Example 7

medium

1500 \text{ kg}

car at

20 \text{ m/s}

collides with a

1000 \text{ kg}

car at rest; they stick. Find the wreck's speed and the KE lost.

Example 8

hard

4 \text{ kg}

object at

6 \text{ m/s}

collides elastically with a stationary

2 \text{ kg}

object. Find both speeds afterward.

Example 9

medium

0.06 \text{ kg}

tennis ball is hit by a racket: it comes in at

25 \text{ m/s}

and leaves at

-30 \text{ m/s}

. Find the impulse on the ball.

Example 10

easy

A 3 kg object moves at

4\,\text{m/s}

. Find its momentum.

Example 11

easy

Why do airbags reduce injury in a collision?

Example 12

easy

What single quantity is conserved in every collision (no external forces)?

Example 13

easy

A 2 kg ball at

5\,\text{m/s}

hits a 2 kg ball at rest. Total momentum before the collision is what?

Example 14

medium

0.2 \text{ kg}

ball traveling at

10 \text{ m/s}

strikes a wall and rebounds at

-8 \text{ m/s}

. Contact lasts

0.05 \text{ s}

. Find the average force.

Example 15

medium

An astronaut (mass

80 \text{ kg}

) at rest throws a

2 \text{ kg}

wrench at

5 \text{ m/s}

in space. Find the astronaut's recoil speed.

Example 16

hard

1 \text{ kg}

cart moving at

8 \text{ m/s}

collides perfectly inelastically with a

3 \text{ kg}

cart at rest. Find the fraction of initial KE retained.

Example 17

challenge

A 4 kg block at

3\,\text{m/s}

collides with a 2 kg block at

-3\,\text{m/s}

; they stick, then slide onto a rough surface with

\mu_k = 0.25

(

g = 10\,\text{m/s}^2

). Find the stopping distance.

Example 18

easy

Impulse on an object equals its change in what?

Example 19

medium

3 \text{ kg}

cart at

4 \text{ m/s}

collides with and sticks to a

5 \text{ kg}

cart at rest. Find their common speed after.

Example 20

medium

2 \text{ kg}

ball at

5 \text{ m/s}

collides head-on elastically with a

2 \text{ kg}

ball at

-3 \text{ m/s}

. Find both velocities afterward.

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Related Concepts

Impulse Conservation of Momentum Elastic Collision Inelastic Collision