hi, reading over momentum notes and i just want to clarify a few things.

if i had a system containing a cart that was moving (cart 1) and then a cart that was stationary (cart2)would there be any net external force acting on the system between the initial position of cart 1 and the final position of the two carts, after they have collided? if there isn't any net external force acting on the system, then is it fair to say that the momentum before the collision is equal to the momentum after the collision? Also, would the final velocity be greater than the initial velocity?

Hi! I'd be happy to help clarify these concepts for you.

When analyzing the momentum in a system, it's important to consider whether any external forces are acting on the system. An external force is a force that originates from outside the system. In your scenario, if there are no external forces (such as friction or gravitational forces) acting on the carts between the initial and final positions, then we can say that there is no net external force acting on the system.

According to Newton's third law of motion, if there is no net external force on a system, the law of conservation of momentum applies. This means that the total momentum of the system before the collision is equal to the total momentum after the collision. So, in your case, if there are no external forces, the momentum before the collision is indeed equal to the momentum after the collision.

However, it's important to note that the momentum of each individual cart can change during the collision. Momentum is a vector quantity, so it includes both magnitude and direction. In a collision, the carts may exchange momentum, resulting in changes in their velocities, but the overall total momentum of the system remains constant.

Regarding your question about the final velocity being greater than the initial velocity, it depends on the specifics of the collision. In an elastic collision, where there is no loss of kinetic energy, it is possible for objects to bounce off each other, resulting in a change in velocities. In this case, the final velocity of one or both carts could be greater than the initial velocity. However, in an inelastic collision, where there is a loss of kinetic energy, the final velocity may be lower than the initial velocity.

To determine the final velocities in a collision, you would need additional information such as the masses of the carts and the nature of the collision (elastic or inelastic). Then, you can use momentum conservation equations and apply the principles of physics to calculate the final velocities.

I hope this helps! Let me know if you have any further questions.