Question

A 2750 kg truck is moving with a speed of 30 m/s. The truck collides with a 1800 kg car that is moving in the same lane and same direction with a speed of 10 m/s. After the collision, the car is moving 23 m/s still in the same direction. What is the velocity (magnitude and direction) of the truck?

Answer 1

Answer: 21.50 m/s

Step-by-step explanation:

Impact Equation

m1v1 + m2v2 = m1v1' + m2v2'

Knowns:
m1 = 2750 kg

m2 = 1800 kg

v1 = 30 m/s

v2 = 10 m/s

v1' = ? (The ' indicates speeds AFTER the impact)

v2' = 23 m/s (The ' indicates speeds AFTER the impact)

Rearrange the equation for v1':

v1' = (m1v1 + m2v2 - m2v2') / m1

v1' = ((2750 kg * 30 m/s) + (1800 kg * 10 m/s) - (1800 kg * 23 m/s)) / 2750 kg

v1' = ((82,500 kg*m/s) + (18,000 kg*m/s) - (41,400 kg*m/s)) / 2750 kg

v1' = (59,100 kg*m/s) / (2,750 kg)

v1' = 21.50 m/s