Question

A 1300 kg car is stopped at a traffic light. A 3000 kg truck moving at a speed of 8 m/s hits the car from behind. If the cars stick together, how fast will they be moving into the intersection?

Answer 1

v = 5.58 m/s

Step-by-step explanation:

Momentum of the truck = mass of the truck x velocity of the truck

= 3000 kg x 8 m/s

= 24000 kg·m/s

Momentum of the car = mass of the car x velocity of the car

= 1300 kg x 0 m/s

= 0 kg·m/s

Total momentum before = Momentum of the truck + Momentum of the car

= 24000 kg·m/s + 0 kg·m/s

= 24000 kg·m/s

Total mass after = mass of the car + mass of the truck

= 1300 kg + 3000 kg

= 4300 kg

Total momentum before = Total momentum after

24000 kg·m/s = (1300 kg + 3000 kg) x v

24000 kg·m/s = 4300 kg x v

v = 24000 kg·m/s / 4300 kg

v = 5.58 m/s