Question

A toy train of m=0.60 kg moves at 20m/s along a straight track. It bumps into another train of M=1.5kg moving in the same direction. They stick together and continue on the track at a speed 12 m/s. What was the speed in m/s of the second train just before the collision?

Answer 1

Answer:8.8 m/s

Explanation:

Given

mass of train $m_1=0.6 kg$

velocity of Train $v_1=20 m/s$

mass of another train $m_2=1.5 kg$

Final velocity of both train $v=12 m/s$

Let $v_2$ be the velocity of $m_2$ before collision

As external Force is zero therefore change in momentum is zero

conserving Momentum

$m_1v_1+m_2v_2=(m_1+m_2)v$

$0.6\times 20+1.5\times v_2=(0.6+1.5)\cdot 12$

$1.5\times v_2=25.2-12$

$v=\frac{13.2}{1.5}=8.8 m/s$