Impulse Lab

The purpose of this lab was to identify the relationship between impulse, force and time during a collision. Beginning the lab, we defined what impulse actually was. We came to the conclusion that impulse is a change of momentum or the conservation of momentum in a collision. 

Important Info and Lab Summary: To find the relationship between impulse, force and time, we conducted an experiment using a red car, a metal track, range finders on either side of the track and metal bands attached to the cars and the end of the track. The metal bands were used to slow down the collision time. Sending the analysis from the range finders to the computers, we were able to see the entire journey of the car - before, during and after the collision. We pushed the red car towards the left of the track ( - sign ) and it immediately bounced back, it was an elastic collision. We then used the graph on the computer to extract the mean and integral of the red car. 

Key Data: 
- Impulse = momentum final - momentum initial (Pf-Pi)
- Impulse equation: J=F (force) X T (time)
- Impulse is a constant on an object in a collision
- Impulse = area of force vs. times graph
- Force and time are inversely proportional

Real World Connection: A bullet proof vest is something that is critical for all policemen and women to wear. The vest has the ability to protect the person from a severe bullet wound and slow down the momentum of the bullet from projecting further at the time of collision. The vest creates an impulse which allows the bullet to take more time before reaching the Cop, decreasing the force or impact they would feel. 

Collisions Lab

The purpose of this lab was to develop our understanding of momentum and the amount of energy stored in both an elastic vs. inelastic collision. The big question being: Is energy or momentum better conserved in a collision?

Important Info and Lab Summary: To simulate a collision, we used a red and blue cart and placed them on a straight metal track. Using range finders on both sides, we collected their velocity or speed throughout the entire collision (before and after). To perform an elastic collision we arranged the carts so that their springs stuck out in front of each other, we then pushed them into each other for a collision. The result being that they bounced off but went in the same direction (left). The red cart started motionless (at rest) while the blue car was pushed towards it, once they hit then the collision occurred. My group noticed that a transfer of momentum was taking place. The red car, which began with no velocity, was in in motion after the collision - meaning that momentum must have been transferred from the blue cart to the red. The second step was to perform and inelastic collision.  We pushed the red cart towards the blue cart (was still) and they almost immediately attached together (Velcro force b/w them) and continued to travel in the same direction (left).

Key Data:

- p=mv (momentum = mass X velocity)

- Energy loss in inelastic > Energy loss in elastic ** both cars are absorbing the energy

- In elastic collisions cars store more energy in kinetic form

Real World Connection: All golf is is collisions! The energy from a club is transferred to a ball that is at rest prior to the hit.

Rubber Band Car Launcher Lab

The purpose of this lab was to discover the relationship between velocity, mass and energy. In our experiment we used an air track, red launcher "cart" and a rubber band. In order to introduce potential energy into the experiment, we had to pull the cart towards us (towards rubber band), and then release the cart which would then travel in a forward motion.

Important Info and Lab Summary: As the cart moved away from the rubber band, we realized that kinetic energy was being transferred due to the fact that the cart was in motion. It became clear that as we stored more energy in the rubber band, more speed/velocity was the product. In conclusion, we figured out that energy and velocity contain a direct relationship. The more energy stored in the rubber band, the further and faster the cart will move when that energy is released. The proof to our consensus was in the data we took from launching the cart from 1-5 cm of the stretched rubber band.

Key Data:
- K = kinetic energy (energy in motion)
- K=1/2 mass X v^2
-Ug = gravitational potential energy (effect of gravity on downward pull of object when lifted at a certain height
- mg = mass X acceleration due to gravitational pull
- h = height of lift
- Ug = mgh

Real World Connection: A fun toy for the upcoming car-obssessors, when winding back the Hot Wheels, the spring inside becomes fully loaded. This allows the car to accelerate (energy transfers to kinetic) and charge ahead without having to be pushed.