a 1500 kg car moving at 20 m/s strikes a truck waiting at a traffic light, hooking the bumpers. The two continue to move together at 10 m/s. What was the mass of the truck?
To find the mass of the truck, we can use the principle of conservation of momentum. The total momentum before the collision is equal to the total momentum after the collision.
Before the collision, the car is moving at 20 m/s, and its mass is 1500 kg. Therefore, the momentum of the car before the collision is given by:
Momentum of car before collision = mass of car * velocity of car
= 1500 kg * 20 m/s
= 30,000 kg·m/s.
Since the truck is initially at rest, its momentum before the collision is zero.
After the collision, the car and the truck continue moving together at 10 m/s. The total momentum after the collision will be the sum of the momentum of the car and the momentum of the truck.
Total momentum after collision = Momentum of car after collision + Momentum of truck after collision.
Since the two vehicles are moving together at the same velocity, their final momentum will be equal.
Total momentum after collision = (mass of car + mass of truck) * velocity after collision.
We are given that the total momentum after the collision is 30,000 kg·m/s, and the velocity after the collision is 10 m/s.
Therefore, 30,000 kg·m/s = (mass of car + mass of truck) * 10 m/s.
To find the mass of the truck, we need to rearrange the equation:
mass of truck = (total momentum after collision) / velocity after collision
= 30,000 kg·m/s / 10 m/s
= 3000 kg.
Therefore, the mass of the truck is 3000 kg.
1500 * 20 = (1500+m)10
m = 1500