Question

Two bodies of masses $0.1kg$ and $0.4kg$ move towards each other with velocities $1m/s$ and $0.1m/s$ respectively. After collision they stick together. In $10s$ the combined mass travels a distance of :

• A. $zero$
• B. $12m$
• C. $0.12m$
• D. $1.2m$

Answer 1

The correct option is D $1.2m$

Mass of first body is $m_1=0.1kg$ and its velocity before collision $u_1=1m/s$

Mass of second body is $m_2=0.4kg$ and its velocity before collision $u_2=-0.1m/s$ (moving in opposite direction)

Let the velocity of combined mass just after collision be $V$.

Using conservation of linear momentum :

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

$\therefore \left(0.1\right)\left(1\right)+\left(0.4\right)(-0.1)=(0.1+0.4)V$

$⟹$ $V=0.12m/s$

Time $t=10s$

Distance covered $S=Vt=0.12\times 10=1.2m$