REFLECTION

Elastic Collisions

From the data in all three elastic collision cases, were the momenta and energies conserved?

Justify your reasoning. Should they have been conserved? Explain why or why not.

If either the momentum or energy was not conserved, offer an explanation of what may have happened in the experiment to be responsible for any loss.

Do you notice any kind of pattern of behavior after the collision depending on whether the target or projectile is more massive? If it is not obvious from the single trial you made, look at the signs on your velocities and qualitatively repeat the experiment with a few different speeds and observe the results.

Inelastic Collisions 4. From the data in the inelastic collision, were the momenta and energies conserved? Justify your

reasoning. Should they have been conserved? Explain why or why not.

Explosions

From the data in the explosion, was momentum conserved? What should the final net

momentum have been? Offer an explanation for why it may not have been conserved. Was there something you might have done accidentally or some unseen physical effect that could have given extra momentum to or taken some momentum from one of the two pieces?

What do you notice about the momentum and kinetic energies of the two roughly-equal-mass carts? (Note: this distribution in momentum is always true for any unequal masses, but not necessarily for kinetic energies of unequal masses.)

I made you find the spring constant simply because I didn't know it and didn't want to rig up with some absurdly elaborate contraption with springs and scales to measure it directly myself. You've used Physics to do something applicably useful. Enjoy.

Quality Control

We sent a single cart through the photogates for a reason. Was its momentum unchanged as it

rolled down the cart? Should it have been?

Examine the percent loss in momentum and energy for the lone cart. Compare the lone cart's percent loss to the percent loss in the other cases. Given this new finding, can you now refine your answer as to whether the momenta and kinetic energy were conserved in the situations you explored?