Practice Inelastic Collision 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 in which the total momentum of the system is conserved but the total kinetic energy is not — some kinetic energy is converted.

Two cars crashing and sticking together: they move as one object and kinetic energy is lost.

Showing a random 20 of 50 problems.

Example 1

hard

Ballistic pendulum: a

0.01 \text{ kg}

bullet embeds in a

0.99 \text{ kg}

pendulum at rest. The combined block rises

0.45 \text{ m}

(

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

). Find the bullet's initial speed.

Example 2

medium

A 2 kg cart at

6\,\text{m/s}

sticks to a 4 kg cart at rest. Find the common velocity.

Example 3

medium

1 \text{ kg}

ball at

10 \text{ m/s}

hits a

3 \text{ kg}

ball at rest; they stick. Find

v_f

and the fraction of KE retained.

Example 4

easy

Total momentum before a perfectly inelastic collision is

20\,\text{kg}\cdot \text{m/s}

and the combined mass is

5\,\text{kg}

. Find the final speed.

Example 5

easy

Energy lost in an inelastic collision goes mainly to what forms?

Example 6

hard

4 \text{ kg}

block at

6 \text{ m/s}

sticks to a

2 \text{ kg}

block at rest; the combined mass slides onto a

\mu_k = 0.5

patch (

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

). How far does it slide?

Example 7

challenge

A 3 kg cart at

4\,\text{m/s}

collides and sticks with a 1 kg cart moving toward it at

4\,\text{m/s}

. Find the final velocity and the percentage of kinetic energy lost.

Example 8

medium

A 0.05 kg bullet at

400\,\text{m/s}

embeds in a 1.95 kg block at rest. Find the speed of the block-plus-bullet.

Example 9

medium

A perfectly inelastic collision happens between equal masses, one at rest. What fraction of the initial KE is lost?

Example 10

medium

Two clay balls, 2 kg at

6\,\text{m/s}

and 3 kg at

-1\,\text{m/s}

, collide and stick. Find the final velocity.

Example 11

medium

A 2 kg block slides at

9\,\text{m/s}

and catches a 1 kg block at

3\,\text{m/s}

(same direction); they stick. Find the final velocity.

Example 12

medium

Why is momentum conserved in an inelastic collision even though kinetic energy is not?

Example 13

medium

6 \text{ kg}

object initially moving at

5 \text{ m/s}

collides with and sticks to a stationary object; the combined system ends at

3 \text{ m/s}

. Find the unknown mass.

Example 14

medium

2 \text{ kg}

4 \text{ m/s}

hits and sticks to

3 \text{ kg}

moving the same direction at

1 \text{ m/s}

. Find

v_f

Example 15

medium

A 5 kg object at

4\,\text{m/s}

collides and sticks with an object, ending at

2\,\text{m/s}

. Find the mass of the second object (initially at rest).

Example 16

challenge

0.02 \text{ kg}

bullet at

400 \text{ m/s}

embeds in a

4 \text{ kg}

wooden block hanging on a string (

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

). Find the maximum angle through which the block swings if the string is

1 \text{ m}

long.

Example 17

easy

0.4 \text{ kg}

glob of clay at

5 \text{ m/s}

hits and sticks to a

0.1 \text{ kg}

glob at rest. Find

v_f

Example 18

easy

Which quantity is conserved in an inelastic collision: momentum, kinetic energy, or both?

Example 19

easy

Two

2 \text{ kg}

lumps move at

+3 \text{ m/s}

and

-1 \text{ m/s}

and stick. Find

v_f

Example 20

medium

A 0.1 kg ball of clay at

12\,\text{m/s}

sticks to a 0.3 kg ball at rest. Find the common speed.

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Related Concepts

Conservation of Momentum Kinetic Energy Elastic Collision