Question

A boy of mass 45 kg running 6 m/s jumps onto a 30 kg trolley moving in the same direction at 1.5 m/s. Their common velocity will be:​

Answer 1

Answer:

4m/s is your common velocity.

Answer 2

Given:

A boy of mass 45 kg running 6 m/s jumps onto a 30 kg trolley moving in the same direction at 1.5 m/s.

To find:

Common velocity ?

Calculation:

• Since no external force is applied, the net linear momentum of system is conserved.

Applying CONSERVATION OF LINEAR MOMENTUM principle:

$m_{b}u_{b} + m_{t}u_{t} = (m_{b} +m_{t})u_{c}$

$\implies (45 \times 6) + (30 \times 1.5)= (45 + 30)u_{c}$

$\implies 270 + 45= 75u_{c}$

$\implies 75u_{c} = 315$

$\implies u_{c} = 4.2 \: m {s}^{ - 1}$

So, common velocity will be 4.2 m/s.