Physics conservation of momentum

Question

11. A cannonball is originally at rest inside of a stationary cannon. The cannonball is then shot out with a

momentum of 4000 kg*m/s to the right. What momentum does the cannon have after launching the cannonball?

a. Less than 4000 kg*m/s to the right b. 4000 kg*m/s to the right c. 4000 kg*m/s to the left d. Zero momentum

12. Two ice skater are travelling towards each other at the same speed. One is 60 kg and travelling to the

left while the other is 40 kg and travelling to the right. If they collide and hold onto each other, which direction will they travel after the collision?

a. Towards the left . b. Towards the right c. They will end up stationary d. More information is needed

14 A 3.0 kg ball is thrown towards a wall with a speed of 5.0 m/s. The ball hits the wall and bounces back

at a speed of 2.0 m/s in the opposite direction. What change in momentum does the ball experience due to the wall?

a. 3.0 kg m/s . b. 6.0 kg m/s c. 14 kg m/s d. 21 kg m/s

Answer 1

I can give you the answers, but that won't help you. I will talk you through them, you see if you can solve the problems with some help.

Problem 11: Apply conservation of momentum. Conservation of momentum states that the momentum before an incident is the same as the momentum before. Momentum is the product of mass and velocity If the cannonball and cannon are initially at rest, their velocities are zero, so their momentums are zero. Conservation of momentum says that the total momentum of the cannonball / cannon system must be zero after the cannonball is fired. So if the cannonball is moving to the right with a momentum of 4000 kg m/s, what must be true of the cannon for the total momentum to be zero?

Problem 12: Also conservation of momentum. If they are traveling toward each other with the same speed, but one has a greater mass, then the one with the greater mass has the greater momentum. The total momentum is the difference between the momentums of the two, in the direction of motion of the skater with the greater mass. After they meet, the total momentum is unchanged, by conservation of momentum.

Problem 14: A change in momentum is the [final momentum - initial momentum]. Define one direction as positive, the other as negative (traditionally right is positive), find the momentum before and after (mass X velocity = momentum), take the difference...