1. A railroad car with a mass of 12,000 kg collides with another with a mass of 20,000 kg that is at rest initially and they couple after the collision. If the car that comes to collide initially has a speed of 12 m/s, what is their speed together after the collision in m/s.

2. A truck of mass 4,000 kg at a speed of 10 m/s due east collides head-on with a carof mass 1,200 kg at a speed 20 m/s duewest.Afterthecollision two vehicles arestuck together. What is the total momentum of these vehicles together in units of 10⁴kg m/s?If they go east (west), the momentum is positive (negative). Include the sign toindicate which direction they go after the collision (positive momentum value foreast and negative value for west). If your answer is 20000 kg m/s (20x10⁴ kg m/s) , you simply write 20 as your answer.

3. During a time period of 0.04 s, a force of average strength of 300 N is applied. How much is the change in momentum of the ball in kg m/s. First calculate the impulse and then the change in momentum.

4. A car carrying a driver and a front-seat passenger of mass 60 kg initially is moving with a speed 18 m/s. The car is then slowed down to rest by an air bag in a time period of 0.4 s. Find the average force in N on the front-seat passenger during this time period. First calculate the impulse and then the average force.Do not use a comma to separate every three-digits.

5. There are two ice skaters with mass 80 kg and 32 kg at rest on ice initially. When one of them (heavier skater) pushes off against the other (lighter skater), and the heavier skater starts to move with a speed of 3 m/s. What is the speed of the lighter skater in m/s? Note that the distinguish the positive direction from the negative direction, and the heavier skater moves in the positive direction.