Question

A lorry of mass 8 000 kg travelling at 20 m s¹ collides with a car of mass 1 000 kg that parked at the side of the road. After the collision, the lorry and the car move together. Calculate the velocity after the collision.​

Answer 1

Step-by-step explanation:

Before the collision, the lorry has a momentum of:

p1 = m1v1 = 8000 kg * 20 m/s = 160000 kgm/s

where m1 is the mass of the lorry and v1 is its velocity.

The car is initially at rest, so its momentum is:

p2 = m2*v2 = 0

where m2 is the mass of the car and v2 is its velocity.

After the collision, the two vehicles move together with a common velocity v. The total momentum of the system after the collision is:

p = (m1 + m2)*v

where m1 + m2 is the total mass of the system.

By the law of conservation of momentum, the total momentum before and after the collision is the same. So we have:

p1 + p2 = p

Substituting the values we have:

160000 kg*m/s + 0 = (8000 kg + 1000 kg)*v

Simplifying:

v = (160000 kg*m/s) / (9000 kg)

v = 17.78 m/s

Therefore, the velocity of the lorry and car together after the collision is 17.78 m/s.