For our next experiment using the NXT robot, we conducted (and then watched) an experiment dealing with varying weights on a pulley system. The goal was to better understand some of Newtons fundamental laws of physics and the law of conservation of energy by experimenting with mass, velocity, and power. Setting up for the experiment was mostly done for us pre-class, but we had to familiarize ourselves with the different types of weights and how to attach and detach them, as well as how to make the pulley lift the weights through the NXT. We also had to use a ruler and manually measure the distance traveled by the weights for each test, so there is a margin of error involved in the experiment.

The first thing we wanted to explore was Newton’s 2nd law (F = ma) by setting up the experiment two different ways. The first method we tested was as follows: We kept a consistent amount of weight for the pulley to lift for three trials, and increased the power level during each trial (from 40, to 60, to 100 [full power]). The results are shown in the following graph:

This shows that increased power level had a direct correlation with increased acceleration.

The next experiment was to test if mass affected the rate of acceleration:

This graph shows that decreasing the mass has a direct correlation with increasing acceleration.

The next step was to explore the law of conservation of energy. The method we used for this was to take a statistic logged by the LabView program, battery discharge (which records the amount of energy expelled by the battery during its mechanical operation), and compared it as we changed the mass of the weight on the pulley. The power level used stayed consistent at 40. The results showed:

This test showed that as the mass increased, the battery needed to expel greater amounts of energy to perform the work.

Lastly, we were tasked with testing how the change in power level affected the overall power of the robot’s motor. This test was easy to predict but it was important to test regardless, since you want to make sure your motor is functioning properly. The results were:

The graph shows that power increased directly with the increase in power level. This was the expected result

Overall the pulley experiment was a success and showed our group firsthand how certain variables like mass and power level affect acceleration and other areas of physical science theory.