Question

Two identical blocks A and B connected by a massless string are placed on a frictionless horizontal plane. A bullet having same mass moving with a speed $u$ strikes block B from behind as shown. If the bullet gets embedded into the block B, then find the velocity of center of mass of A, B and C after collision ?

• A. $\frac{u}{3}$
• B. $\frac{2u}{3}$
• C. $\frac{u}{6}$
• D. $\frac{u^2}{3}$

Answer 1

The correct option is A $\frac{u}{3}$

Now apply momentum conservation we get,

$m_1{u}_1$+$m_2{u}_2$=$m_1{v}_1$+$m_2{v}_2$

$mu$+0=0+$3mv$

$v=$$\frac{u}{3}$