Elastic and inelastic collisions

Answer Key - Grade 11 Science Worksheet - Challenge Me

Circle the best answer, or write your answer on the line.

1. 1.

   A 3 kg cart hits a 1 kg cart at rest and they stick together. What percent of the kinetic energy is kept, Ari?

   75 %
2. 2.

   A 4 kg cart hits a 1 kg cart at rest and they stick together. What percent of the kinetic energy is kept, Bo?

   80 %

3. Read this first

   Collision trials for two carts (example data)

   trial	kinetic energy before (J)	kinetic energy after (J)	carts after
   P	12	12	bounce apart
   Q	12	8	bounce apart
   R	12	4	stuck together

4. 3.

   In the trials table, about what percent of its kinetic energy did trial Q keep, Jun?

   • About 33%
   • 100%
   • About 8%
   • About 67%
5. 4.

   The carts in the trials table ran on a smooth, level track. Which trials conserved momentum, Kira?

   • None of them
   • Just P and Q
   • Just trial P
   • All three
6. 5.

   In the trials table, where did trial R's lost 8 J go, Luz?

   • It stayed as kinetic energy
   • Into heat, sound and bending
   • It was destroyed
   • Into extra momentum
7. 6.

   Noah says kinetic energy is conserved in every collision. Agree or disagree?

   • Agree: kinetic energy is always kept
   • Agree: energy can't change form
   • Disagree: only elastic ones keep it
   • Agree: momentum and kinetic energy are the same thing
8. 7.

   Pia says that in an inelastic collision the total energy is still conserved. Agree or disagree?

   • Disagree: kinetic energy is kept, so nothing changes
   • Disagree: the lost energy is destroyed
   • Disagree: momentum is lost too
   • Agree: the lost kinetic energy changes form
9. 8.

   A 1 kg cart at 4 m/s hits an identical cart at rest in an elastic collision. What happens, Ren?

   • The first stops; the second moves at 4 m/s
   • The first bounces back at 4 m/s
   • Both move at 2 m/s
   • Both stop
10. 9.

    The same carts stick together instead. What happens, Tala?

    • They move at 2 m/s and 4 J is lost
    • They move at 2 m/s and no energy is lost
    • They move at 4 m/s and no energy is lost
    • They stop
11. 10.

    Comparing the elastic and the sticking collisions of those carts, what is the same, Zee?

    • Each cart's speed after
    • The kinetic energy after
    • Nothing
    • The total momentum after