Impulse Lab

Lab Work:
      In our most recent lab, we performed experiments using the equation for momentum,
P=mV, and the equation for Impulse, J=P(after) - P(before). 

      Our actual test consisted of crashing a cart with a metal ring into a force probe stand with a metal ring. The force probe helped us to calculate the force of the collision. And at the end of the track we also placed a sonar device, which allowed us to calculate the velocity of our cart before and after the collision. We had to perform this test a few times in order to get the data we needed to use. 

(The graph above shows the data we collected from our collision. The blue bar on the bottom was the data we used to find our velocity before and after the collision.)

      Our whiteboard above shows the calculations we made after completing our lab. We used the momentum equation, P=mV to find the momentum of the cart before and after the collision. The mass remained the same at 0.25k. Before the collision, the velocity was 0.3714m/s, and after the collision the velocity was -0.3421m/s. After we had our values for momentum, we subtracted the momentum before the collision from the momentum after the collision. This value would be our impulse for the collision. 

(We also calculated our percent error as shown on the board and found that we had a twenty percent difference.)

Real World Application:

      In our world today, one example of this lab would be a car crash. Now this type of car crash wouldn't involve another car like some of our previous labs. Instead of a car crashing into another vehicle, this car would crash into a wall or something immovable. 

Crash test cars are an excellent example of this concept in real life. By crashing a car into a solid wall, people are able to record impulse, momentum, velocity and many other important factors just like we did in our impulse lab. 

Collisions Lab

Big Question:

"What is a better conserved quantity - momentum, or energy?"
-After completing our collisions lab and collecting our data, we found that momentum is a better conserved quantity as opposed to energy. With energy, both cars start out with kinetic energy, but when they collide, the energy is transfered to heat, or possibly friction. 

Lab Work:
      We began our lab by setting up two cars on a track facing each other. On either end of the track itself we had sonar sensors which would allow us to calculate the velocity of the cars. Our first test was "elastic" meaning that each car would have springs colliding with each other on the ends of the cars. The red car was stationary and we rolled the blue car into it. The blue car stopped moving and the red car was pushed down the track.This was our first test for the "elastic" collision.

      Our second test was an "inelastic" collision where we took the springs away from the cars. This time, when we ran the blue car into the red car, both cars stayed together and continued rolling down the track. 

      Our data involving momentum, energy, and velocity are recorded below:

(We used the formula, P = mv, to calculate momentum, and the formula, K = 0.5mV^2, to calculate the energy.)

Percent Difference:

      This whiteboard shows how we calculated the percent difference of energy and momentum. We calculated the percent difference of the energy and momentum by first subtracting the "before" number from the "after" number. Then we divided that number by the average of the two numbers. We then took that number and multiplied it by 100 to give us our percent difference value.

Real World:

      In our world today, one of the most obvious examples is a car crash. When one car crashes into the other, both of the cars continue moving a little. The kinetic energy of the cars is transfered into heat or friction and the momentum of the cars is conserved. This is an example of an "inelastic" collision as performed in our lab.