Rubber Band Cart Launcher Lab

The BIG Question
      How are energy and velocity related?

• In Physics class this week, we tested to see how energy and velocity are related. To do this, we launched a glider at different distances on an air track. We measured the velocity using a Photogate Sensor, which detects the speed of the glider as it passes through. It works by creating an infrared beam and timing how long this beam is blocked by the glider. In order to get the most accurate data we possibly could, we leveled out the air track so that there no spontaneous movement of the glider. By turning the screw under the air track, we leveled the slope of the air track to make it flat.

• During the experiment we measured the velocity at 5 amounts of the rubber band stretched. Here are our calculations and data:                                                                                                                          

• Then we graphed our data using our Graphical Analysis App on our Ipads. Here's what our graph looked like:

• Post Analysis Questions:

1. The mass of the red cart is 0.38kg. How do you think the slope and the mass of the glider relate? 

• We found that the slope of the line, 0.147 v^2/J, is about 1/2 the mass of the cart. 

1. Can you derive an equation relating energy (KE), mass (m, and velocity (v^2)?

• To find our equation, we started the y = mx +b, the equation of a line. Then we plugged in the information we had with the variables we're supposed to use and got KE = .147 (v^2) + 0. Then using the answer to our first analysis question, we saw that mass has to be related. So we plugged 1/2 (mass) in for the slope and got KE = 1/2 (m) (v^2) as our final equation.

• Real Life Connection: In physics, the phrase "kinetic energy" is used to describe the energy of motion. Any object in motion possesses kinetic energy, and this energy can be controlled, transferred, and transformed to do work. A dancer holds much kinetic energy. Moving in a constant direction creates momentum. Momentum is mass in motion. The amount of momentum depends on the amount of mass moving and how fast that mass is moving. This shows how much or how little a dancer can have while performing. Momentum and speed, or mass and velocity, make up kinetic energy in a dancer.