Q21Long answer
A light and a heavy object have the same momentum. Find out the ratio of their kinetic energies. Which one has a larger kinetic energy?
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p1 = m 1v 1 p 2 = m 2 v 2 But p1 = p2 or m 1v 1 = m2v2 If m1< m2 then v1> v 2 1 1 (K.E)1 = m1v12 (K.E)2 = m 2v 22 2 2 1 1 1 1 (K.E)1= (m 1v 1 ) v1 = p1 v1 (K.E)2 = (m 2v 2 ) v 2 = = p2 v 2 2 2 2 2 (K.E)1 p 2 v1 v = 2 = 1 (K.E)2 1 p2 v 2 v 2 But v 1> v 2 Therefore, (K.E.)1 > (K.E)2