A ball with a mass of #10 kg# moving at #18 m/s# hits a still ball with a mass of #30 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?

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Answer 1 · 2018-05-14T16:03:30

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=10kg#

The velocity of the first ball before the collision is #u_1=18ms^-1#

The mass of the second ball is #m_2=30kg#

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,

#10*18+30*0=10*0+30*v_2#

#30v_2=180#

#v_2=180/30=6ms^-1#

The velocity of the second ball after the collision is #v_2=6ms^-1#

The loss in kinetic energy is

#DeltaKE=KE_i-KE_f#

#=1/2*10*18^2-1/2*30*6^2#

#=1620-540#

#=1080J#

The kinetic energy lost in the collision is #=1080J#