A ball with a mass of #6 kg# moving at #16 m/s# hits a still ball with a mass of #10 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 · 2017-10-11T17:00:49

#9.6ms^(-1)#

KE loss#=307.2#

let us lay out what we know

Object 1

mass#=6kg#

initial velocity#" "u_1=16ms^(-1)#

Final velocity#" "v_1=0ms^(-1)#

Object 2

mass#=10kg#

initial velocity#" "u_2=0ms^(-1)#

final velocity#=v_2ms^(-1)" "#to find

we shall use the conservation of linear momentum

we have

#6xx16+10xx0=6xx0+10v_2#

#96=10v_2#

#=>v_2=9.6ms^(-1)#

KE loss

KE initial( before collision)#=1/2xx6xx16^2+0=768J#

KEfinal(after collision)#=0+1/2xx10xx9.6^2=460.8J#

#:." KE loss"=768-460.8=307.2J#

note that this is the total loss of KE. It doesn't all go into heat, some will go into other forms of energy for example sound.