Question

20 pts 4. A 1200 kg car is stopped at a traffic light. A 3500 kg truck moving at 10 m/s hits the car from behind. If the carsstick together, how fast will the two vehicles move after the collision?

20 pts 5. Joe and his brother Bo have a combined mass of 300 kg and are zooming along in a 200 kg amusement park bumper car at 10 m/s. They bump into Melinda's car, which is sitting still. The two cars do not stick together. Melinda has a mass of 50 kg, her car also has a mass of 200 kg. After the collision, the twins continue ahead with a speed of 4.5 m/s. How fast is Melinda's car moving after the collision?

20 pts 6. A 4 kg rifle fires a 0.1 kg bullet at a speed of 300 m/s, find the recoil velocity of the rifle.

10 pts 7. How much force is required to stop a 10000 kg train car traveling at 5 m/s during a time of 5.0 seconds?

20 pts . A tennis ball may leave a top player’s racket on the serve with a speed of 65.0 m/s. The ball’s mass is 0.0600 kg and it is in contact with the racket for 0.0300 s. Assume the ball begins at rest.

a. What is the change in momentum of the tennis ball during the collision with the racket?

b. What is the force exerted on the ball by the racket?

Answer 1

llision, Joe and Bo's car moves away at 6 m/s in the opposite direction. What is the velocity of Melinda's car after the collision?

For problem 4, we can use the law of conservation of momentum, which states that the total momentum of a closed system is conserved.

Initially, the momentum of the system is:

p1 = m1v1 + m2v2
= 1200 kg * 0 m/s + 3500 kg * 10 m/s
= 35,000 kg m/s

After the collision, the two vehicles stick together and move with a common velocity v. Therefore, the momentum of the system is:

p2 = (m1 + m2) * v
= (1200 kg + 3500 kg) * v
= 4,700 kg * v

Since momentum is conserved, we can set p1 = p2 and solve for v:

35,000 kg m/s = 4,700 kg * v
v = 7.45 m/s

Therefore, the two vehicles will move forward with a velocity of 7.45 m/s after the collision.

For problem 5, we can again use the law of conservation of momentum. Before the collision, the momentum of the system is:

p1 = (300 kg + 200 kg) * 10 m/s + 0 kg * 0 m/s
= 5,000 kg m/s

After the collision, the two cars move in opposite directions with velocities v1 and v2, and Melinda's car moves with a velocity v3. Therefore, the momentum of the system is:

p2 = 200 kg * v1 + 200 kg * v2 + 50 kg * v3
= 200 kg * (v1 + v2) + 50 kg * v3

Since momentum is conserved, we can set p1 = p2 and solve for v3:

5,000 kg m/s = 200 kg * (10 m/s - 6 m/s) + 50 kg * v3
v3 = 20 m/s

Therefore, Melinda's car moves away from the collision with a velocity of 20 m/s.