Question

An empty train car of mass 2.0 x 10^4 kg coasts along at 10 m/s. A 3000-kg boulder is suddenly dropped vertically into the car. Find the speed of the car immediately after the boulder is dropped.

Answer 1

Answer:8.69 m/s

Explanation:

Given

mass of Empty train $m=2\times 10^4 kg$

velocity of car $v=10 m/s$

mass of Boulder $M=3000 kg$

Since no External force is acting therefore conserving Momentum

Train and boulder moves with same velocity after collision

$m v=(M+m)v'$

$2\times 10^4\times 10=(2\times 10^4+3000)v'$

$v'=\frac{20,000\times 10}{23000}$

$v'=8.69 m/s$