A ball with a mass of #12 kg# moving at #8 m/s# hits a still ball with a mass of #16 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 · 2017-06-17T09:41:39

The loss of kinetic energy is #=96J#

#m_1u_1+m_2u_2=m_1v_1+m_2v_2#

The mass #m_1=12kg#

The velocity #u_1=8ms^-1#

The mass #m_2=16kg#

The velocity #u_2=0ms^-1#

The velocity #v_1=0ms^-1#

Therefore

#12*8+16*0=12*0+16*v_2#

#16v_2=12*8=96#

#v_2=96/16=6ms^-1#

The loss in kinetic energy is

#DeltaKE= KE_1-KE_2#

#=1/2m_1u_1^2-1/2m_2v_2^2#

#=1/2*12*8^2-1/2*16*6^2#

#=96J#