Question

A 1250 kg car, driving 7.39 m/s, runs into the back of a stationary 5380 kg truck. After the collision, the truck moves forward at 2.30 m/s. What is the final velocity of the car?

Answer 1

Explanation:

Given that,

Mass of the car, m₁ = 1250 kg

Initial speed of the car, u₁ = 7.39 m/s

Mass of the truck, m₂ = 5380 kg

It is stationary, u₂ = 0

Final speed of the truck, v₂ = 2.3 m/s

Let v₁ is the final velocity of the car. Using the conservation of momentum as :

$m_1u_1+m_2u_2=m_1v_1+m_2v_2$

$1250\times 7.39+5380\times 0=1250\times v_1+5380\times 2.3$

$v_1=-2.5\ m/s$

So, the final velocity of the car is 2.5 m/s but in opposite direction. Hence, this is the required solution.