Rubber Band Launcher

Rubber Band Cart Launcher

Big Question:
How are energy and velocity related?

Key:
m = meters
v = velocity
J = Joules (Energy)
KE or K = kinetic energy
Us = elastic potential energy


Introduction:
In this week's lab we launched a glider from a rubber band using an air track, and used a sensor to measure the velocity. We changed the distance stretched of the rubber band for each trial our independent variable. There were five different distances we had to measure, ranging from 1-5 centimeters. We recorded the velocity of the cart in a table for graphing purposes and then repeated the process. 

Here is our data:

Afterwards, we took our data and put it on the Graphical Analysis App.  It formed this graph

Next Step:
We need to connect this to physics in some way and make an equation that fits our needs as well as our answer the questions to our post lab analysis
1. The mass of the Red cart is 0.38kg. How do you think the slope and the mass of the glider relate?

•  We figured out our slope was 0.216 v2/J which is approximately 1/2 mass of the Red cart.

2. Can you derive an equation using Energy (E), mass (m) and velocity (v2)?

•  y=mx+b is the main equation we are to derive this off of and so we incorporated in information we needed in our new equation. We figured that since the slope was half the mass in the first post-lab analysis question we need to show that in our new equation which came out to be: Energy=.50(m)(v2).

Big Idea:
     The big idea here is energy is always conserved.  How does that apply here?  Well all of the energy before we launched the cart was in the rubber band via potential elastic energy.  Once it was launched, the cart was in motion, and the rubber band was no longer influencing the energy this transferred over into kinetic energy!  Crazy, I know!


Real World Connection:
Being the fantasy nerd that I am, it was only fitting that my thought came to Legolas, from the Lord of the Rings trilogy.  He must have been an amazing physicist because he was so accurate with shooting a bow and arrow and used the equation E= .50(m)(v2) to his best ability in order to help destroy the One Ring in Middle Earth!