Question

A body of mass 2 kg moving with a velocity of 3 m/sec collides head on with a body of mass 1 kg moving in opposite direction with a velocity of 4 m/sec. After collision, two bodies stick together and move with a common velocity which in m/sec is equal to

• A. 1/4
• B. 1/3
• C. 2/3
• D. 3/4

Answer 1

The correct option is C. 2/3.

Given,

$m_1=2kg,u_1=3m/s$

$m_2=1kg,u_2=-4m/s$

Let the final velocity of both the masses be $v$.

From the conservation of linear momentum we have,

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

$\Rightarrow (2\times 3)+(1\times (-4\left)\right)=(2+1)v$

$\Rightarrow v=\frac{2}{3}m/s$.