Question

A 2.0-kg object moving with a velocity of 5.0 m/s in the positive x
direction strikes and sticks to a 3.0-kg object moving with a speed of 2.0 m/s in the same direction. How much kinetic energy is lost in this collision?

Answer 1

m1•v1+m2•v2 =(m1+m2)•u

u= (m1•v1+m2•v2)/ (m1+m2) =
=(2•5+3•2)/(5+3) =2 m/s

m1•v1²/2 + m2•v2²/2 –(m1+m2) •u²/2 =
= 2•25/2 +3•4/2 –8•4/2 =15 J