Collision Lab

Big question:

What is a better conserved quantity in a collision- momentum or kinetic energy?

How we went about investigating the big question:

For our lab, we placed two range finders on a track and used two cars. We then conducted two different collisions. For the elastic collision, Weser the carts up with their spring launchers facing each other, and we then pushed the red car to collide into the blue. We recorded the speed of the carts before and after the collision. For the inelastic collision, we set the carts up with their Velcro sides facing so that they would stick together. We again pushed the red cart towards the blue and recorded the speeds of the carts before and after. 

Answer to the big question:

The answer to the big question was that momentum is the better conserved quantity in a collision. 

Evidence to support answer: 

We used  % difference = [(TOTAL ENERGY_AFTER - TOTAL ENERGY_BEFORE)/(TOTAL ENERGY BEFORE)] x 100% to find the amount of energy that left the system. We then used  % difference = [(TOTAL MOMENTUM_AFTER - TOTAL MOMENTUM_BEFORE)/(TOTAL MOMENTUM BEFORE )] x 100 to find how much momentum left the system. We got the following results: 

 For the elastic collision 7.86% difference of momentum lost was less than the percentage lost for the kinetic energy. In the inelastic collision, the 22% of momentum lost was less than the percentage lost for the kinetic energy as well, so in both collisions momentum was better conserved. 

How I can use what I learned in a new situation: 

I can use the equations for percent difference to figure out how much energy or kinetic energy is lost. I can also use the conservation of momentum theory to plug in and find other values such as velocity.

How this relates outside of class:

This relates to the Large Hadron Collider, which is a particle accelerator. Two high energy particle beams are guided around the tube by electromagnets. The magnets are used to squeeze particles together and increase the chances of collision. This relates to the amount of energy and momentum that is needed in order for the particles to collide.