Pulley Experiment

This experiment gave me a great deal of first hand insight into Newton’s 2nd law. This law states that Force equals mass multiplied by acceleration. Using the Lego Mindstorm robot and a pulley system, we gained insight into the law of conservation as well as power, velocity and acceleration. The pulley was set up by connecting the Lego motor to the LabView program, a cable was connected the battery to a Lego arm piece. The pulley consisted of a string tied around part of the arm piece then around a pulley connected to weights.

Here is the set up:

This is the VI in LabView used to control the pulley:

In the experiment, we changed the mass of the weights by adding or removing pieces connected to the pulley as well as the power level. Initially I thought that speed would be the only thing that changed because the amount of weight was being altered. These minor changes resulted in great differences in acceleration, speed, and power. When applying Newton’s 2nd Law to this experiment, force is represented by power level provided by the Lego Mindstorm motor. Work (work=f) was done as force was applied by the motor, which pulled up the weight. It is also important to note that not all of the energy goes toward lifting the weight. Some energy is lost due to friction.

In Labview each time we ran the experiment we adjusted the power level from anywhere between 0% and 100% and entered the weight we measured. The program recorded millivolts generated, rotation, battery discharge in mV, speed in rate per minute, time in seconds, and acceleration in rpm/second. Below are the results of each time we ran the experiment in the VI that include both our inputs and the program’s recording.

One problem that we did have with recording the data is that we did not do enough tests at each power level, so we are missing some data points. Newton’s 2nd Law suggests that if the mass remains the same and the force is increased, the acceleration will increase. If the mass is increased, the acceleration will decrease.

As I noted previously, not all the energy applied goes toward pulling the weight. Battery discharge accounts for some of the energy lost due to friction. We found that as the mass increased, the battery discharge increased because more energy was put toward pulling the weight.

As we continued to analyze our results we found a positive correlation between power and power level. Power=work/time, meaning that as the power increases, more energy is output.

Overall, this experiment gave me a better understanding of Newton’s Second Law, as well as the law of the conservation of mass. All potential energy must be accounted for as it is not wasted.