A ball with a mass of #14 kg# moving at #2 m/s# hits a still ball with a mass of #20 kg#. If the first ball stops moving, how fast is the second ball moving? How much kinetic energy was lost as heat in the collision?

Question

1430 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2018-05-23T08:38:52

Please see the explanation below

#m_1u_1+m_2u_2=m_1v_1+m_2v_2#

The mass the first ball is #m_1=14kg#

The velocity of the first ball before the collision is #u_1=2ms^-1#

The mass of the second ball is #m_2=20kg#

The velocity of the second ball before the collision is #u_2=0ms^-1#

The velocity of the first ball after the collision is #v_1=0ms^-1#

Therefore,

#14*2+20*0=14*0+20*v_2#

#20v_2=28#

#v_2=28/20=1.4ms^-1#

The velocity of the second ball after the collision is #v_2=1.4ms^-1#

The loss in kinetic energy is

#DeltaKE=KE_i-KE_f#

#=1/2*14*2^2-1/2*20*1.4^2#

#=28-19.6#

#=8.4J#

The kinetic energy lost in the collision is #=8.4J#