30-Sept-2014 Work-KE Theorem Lab

In this lab we wanted to verify that the net work done by a spring on a kart is equal to the change in kinetic energy of the kart.

For this setup we used a force sensor, a loose spring, a kart, a motion detector, and a smooth leveled track. We first found the mass of the kart (with a wooden block mounted to it) and the mass of the spring. Second, we checked and zeroed the force sensor. Third, we zeroed and checked the direction of the motion detector so that it would collect positive values as the kart approached it. The kart is pushed in the direction of the motion detector and begins to stretch the loose spring, after some distance the spring pulls the to a momentary stop before the kart is forced back towards its initial position.

By using LoggerPro to collect data from the sensors we were able to get three graphs that displayed the following: position vs. time, velocity vs. time, Force vs. time. From velocity we were able to create a new set of data points which you can see below in the last column labeled KE for kinetic energy. To do this we used the following equation

KE = .5*m*v^2

Then we plotted KE and F as y-axis values and position for x-axis values. The integral of force is said to be equal to work so to test this we use our fancy software to integrate the area under the graph of the force graph for a closed interval. This gave us a value of 0.8592 Joules and if we look at the value of kinetic energy at that point we see a similar value of 0.807 Joules. Although there is a variance we can at least see that there is a connection between the integral of force and work which is equal to kinetic energy.