- #1

paulimerci

- 287

- 47

- Homework Statement
- Two carts are held together. Cart 1 is more massive than Cart 2. As they are forced apart by a compressed spring between them, which of the following will have the same magnitude for both carts.

(A) change of velocity (B) force (C) speed (D) velocity

- Relevant Equations
- conservation of momentum and Impulse

It's an explosion problem.

When two carts are pulled apart, the bigger one takes longer than the smaller one. So the velocity of the bigger one is small, and the velocity of the smaller one is large, and they are opposite each other. So the momentum before the explosion must be equal to the momentum after the explosion.

The energy is conserved if no energy is lost due to friction or any other external force. If the pulling force is an external force applied to the system, is energy conserved?

The force applied to both the carts should be different if the time taken for the carts to be pulled apart is different. And so the impulse is different for both carts.

I don't know how to interpret the following options given: I know some of the interpretations were wrong, and I would greatly appreciate it if anyone could explain in detail.

When two carts are pulled apart, the bigger one takes longer than the smaller one. So the velocity of the bigger one is small, and the velocity of the smaller one is large, and they are opposite each other. So the momentum before the explosion must be equal to the momentum after the explosion.

The energy is conserved if no energy is lost due to friction or any other external force. If the pulling force is an external force applied to the system, is energy conserved?

The force applied to both the carts should be different if the time taken for the carts to be pulled apart is different. And so the impulse is different for both carts.

I don't know how to interpret the following options given: I know some of the interpretations were wrong, and I would greatly appreciate it if anyone could explain in detail.