Question

A bullet of mass m is fired in the horizontal direction with a velocity u. This bullet gets embedded in a bag of sand lying in a truck. If the mass of truck is M then the velocity of truck after the collision will be-

• A. $\frac{mu}{(M+m)}$
• B. $\frac{m}{(M+m)u}$
• C. $\frac{mM}{(M+m)u}$
• D. zero

Answer 1

Answer: (A)

$\frac{mu}{(M+m)}$

By conservation of Momentum principle,
$M_i=mu$
$M_f=(m+M)v$
$\therefore M_i=M_f=mu=(m+M)v$
$\therefore v=\frac{mu}{m+M}$