question_answer

A big ball of mass M, moving with velocity u strikes a small ball of mass m, which is at rest. Finally small ball obtains velocity u and big ball v. Then what is the value of v             [RPET 2001]

A)          \[\frac{M-m}{M+m}u\]

B)                       \[\frac{m}{M+m}u\]

C)          \[\frac{2m}{M+m}u\]

D)          \[\frac{M}{M+m}u\]

Correct Answer: A

Solution :

From the formulae \[{{v}_{1}}=\left( \frac{{{m}_{1}}-{{m}_{2}}}{{{m}_{1}}+{{m}_{2}}} \right)\ {{u}_{1}}\] We get \[v=\left( \frac{M-m}{M+m} \right)\ u\]