A ball with a mass of #3# #kg# moving at #8# #ms^-1# hits a still ball with a mass of #6# #kg#. If the first ball stops moving, how fast is the second ball moving? How much heat energy was lost in the collision?

Question

1297 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2016-06-21T11:16:11

Momentum will be conserved, kinetic energy will not.

Velocity of the #6# #kg# ball after the collision is #4# #ms^-1#.

The energy lost as heat is #96-48=49# #J#.

Total momentum before the collision is #p=mv=3xx8=24# #kgms^-1#.

Total momentum after is the same so, rearranging, #v=p/m=24/6=4# #ms^-1#.

Kinetic energy before the collision is:

#E_k=1/2mv^2=1/2xx3x8^2=96# #J#

Kinetic energy after the collision is:

#E_k=1/2mv^2=1/2xx6x4^2=48# #J#

The energy lost as heat is the difference: #96-48=49# #J#.