- 36

- 0

I have a lab report due tonight. We were working on these in lab and I'm not sure how to tell which one was elastic or inelastic. We had three cases. We had to use the conservation of momentum and kinetic energy formulas.

A ) Cart A and B have equal masses. Car B is at rest. Car A strikes car B. They don't stick together. Photogate measures different final velocities for each. Conservation of momentum -> 26% difference, and conservation of kinetic energy was 49 % difference.

B) Cart A has larger mass than Cart B. Cart B is at rest. Car A strikes Car B, and again they measure different velocities. Percent difference for momentum was 8.9 % and for kinetic energy it was 26 %.

C.1) Cart A and Cart B have equal masses, but Cart A is inverted, so that the two magnets on each car attract each other, ( I think we are simulating an elastic collision here, but Im not sure). Cart B is at rest. Cart A strikes Cart B and they stick together, both presenting with same final velocities. Momentum % diff. was 8.7% and kinetic energy was 57 %.

C.2)After Cart A, passes the photogate, it measures a different velocity, (slower).

So, the questions are, which collision is inelastic/elastic and why? And what is the importance/use of the second velocity measure in part C?

These are my assumptions, Please tell me if I am correct, and why or why not am I wrong.

A ) The collision is elastic because the carts didnt stick together, and their final velocities were different.

B) The collision is elastic because the carts didnt stick together, and their final velocities were different.

C.1) The collision is inelastic because the carts stuck together, and their final velocities were the same.

C.2) The velocity measure after Cart A passed the photogate is different than when the collision took place because the carts are going slower? I dont know what the importance is though.

Please, any input is appreciated! I'm deperate here, thank you!

A ) Cart A and B have equal masses. Car B is at rest. Car A strikes car B. They don't stick together. Photogate measures different final velocities for each. Conservation of momentum -> 26% difference, and conservation of kinetic energy was 49 % difference.

B) Cart A has larger mass than Cart B. Cart B is at rest. Car A strikes Car B, and again they measure different velocities. Percent difference for momentum was 8.9 % and for kinetic energy it was 26 %.

C.1) Cart A and Cart B have equal masses, but Cart A is inverted, so that the two magnets on each car attract each other, ( I think we are simulating an elastic collision here, but Im not sure). Cart B is at rest. Cart A strikes Cart B and they stick together, both presenting with same final velocities. Momentum % diff. was 8.7% and kinetic energy was 57 %.

C.2)After Cart A, passes the photogate, it measures a different velocity, (slower).

So, the questions are, which collision is inelastic/elastic and why? And what is the importance/use of the second velocity measure in part C?

These are my assumptions, Please tell me if I am correct, and why or why not am I wrong.

A ) The collision is elastic because the carts didnt stick together, and their final velocities were different.

B) The collision is elastic because the carts didnt stick together, and their final velocities were different.

C.1) The collision is inelastic because the carts stuck together, and their final velocities were the same.

C.2) The velocity measure after Cart A passed the photogate is different than when the collision took place because the carts are going slower? I dont know what the importance is though.

Please, any input is appreciated! I'm deperate here, thank you!

Last edited: