Question

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

• A. $\frac{M - m}{M + m}u$
• B. $\frac{m}{M + m}u$
• C. $\frac{2m}{M + m}u$
• D. $\frac{M}{M + m}u$

Answer 1

Answer: (A)

$\frac{M - m}{M + m}u$

Answer 2

From the standard equation

$v_{1} = \left( \frac{m_{1} - m_{2}}{m_{1} + m_{2}} \right)u_{1} = \left( \frac{M - m}{M + m} \right)u$.