Collision Lab

Purpose: In this lab we focused on momentum. We answered the Big Question, "What is a better conserved quantity-momentum or energy?" by colliding the red and blue cars together. We learned about the conservation of energy in inelastic and elastic collisions.

How?: Elastic Collision: In an elastic collision, the two cars do NOT stick together. We set up both cars on opposite ends of the track then pushed the red car into the blue one. Once they collided, they rolled in opposite directions, and the sensors set up of each end of the track recorded the velocity of the cars. We used the graphs on the computer to calculate the velocity before and after the collision.
Inelastic Collision: In this collision the two cars stick together after colliding. We approached this the same way we did with the first collision. We pushed the red car into the blue car, and after they collided both cars stared moving in the initial direction of the red car.

Conclusion: After, we calculated the percent difference of momentum and kinetic energy.
 Pa-Pb ÷ (Pa+Pb)/2    or     KEa-KEb ÷ (KEa+KEb)/2
Momentum is better conserved because more energy is leaving the system during the equation.

Real World: This collisions lab reminded me of playing pool--an example of an elastic equation. When someone shoots the cue ball, it travels and as soon as it collides with another ball, it stops and the other ball travels in its place.

Rubber Band Cart Launcher

Purpose: In this lab, we were introduced to the new concept of velocity. From the data collected, we not only were able to observe the relationship between energy and velocity, but we were also able to observe energy transfer.

How?: First, we set up the sensor gate, which calculated the velocity of the glider. Then we connected the sensor to the LabQuest, which recorded the data. We then turned on the air for the air track, this enabled our glider to slide smoothy across the track with no resistance. We pulled the rubber band back the given distances (1cm,2cm,3cm,4cm,5cm) with the glider in it. When we released the rubber band, the glider passed through the sensor which recorded the average velocity. We then plugged our results into the data table given on the website. We used this table to compare the velocity to the energy results we calculated in last week's lab.

Graph:  After observing our data, we plugged our Velocity as well as Energy results into the data table on the Vernier Graphical Analysis App. This app used our data and created a liner graph and also created a best fit line.

*We then found the slope of the line which was about .2. 
*Derived from "y=mx+b" we used the energy equation E=(slope)(V^)+0----->E=0.2v^
*We then needed to find the constant. We used the equation (Slope)=c(mass)   ("c" being constant.)
*We were given the mass of thecart...0.4kg
* (Slope)=c(mass)  

   0.2=c(0.4kg)

      c=1/2

*From all the equations, we were able to derive the equation for Kinetic Energy

K=1/2mv^

*Slope=1/2m  ("m" being the mass of the object)

The Real World: This lab can also be related to archery in the real world. In the youtube video I posted below, the concept of energy transfer is discussed. When you pull back the arrow, you have potential energy and as soon as you let go, it is converted into kinetic energy. 

http://www.youtube.com/watch?v=b1D6v3kZrHM