This lab activity was an interesting and successful way of exploring Newton’s 2nd Law. In this lab we used the robot along with varying masses and velocity on a pulley system. The equation we used for this activity was F=ma. With this equation we explored conservation of energy and were able to understand rules of Newton’s 2nd Law; that energy is not created or destroyed.
Our procedure in this lab activity was to perform multiple trials where the constant differed. For our first four trials, we kept the mass at a constant weight of 0.09 kg and varied the amount of power of the pulley in each trial. During this trial we were able to draw a hypothesis that when mass remains constant, force and acceleration will also increase (F=ma).
Below is a table of our findings when Mass (kg) was constant with a corresponding graph.
| Speed (RPM) | Battery Discharge | Mass (kg) | Power | Time (sec) | Acceleration (RPM/sec.) |
| 30.850514 | 111 | 0.09 | 50 | 4.511 | 6.838952 |
| 66.496526 | 139 | 0.09 | 75 | 2.351 | 28.284358 |
| 106.949352 | 110 | 0.09 | 100 | 1.415 | 75.582581 |
| 106.567093 | 70 | 0.09 | 125 | 1.406 | 75.794519 |
In conclusion from this trial, as we increased the amount of force on the pulley, the acceleration increased as well. Our results show a positive slope in our graph (best fit line).
For our second trial, we kept the power at a constant level of 50, and varied the mass (kg). During this trial we were able to draw a hypothesis that when mass increases, acceleration will decrease. This means that our equation (F=ma) would not be balanced, as it was in the previous trial.
Below is a table of our findings when Power was constant with a corresponding graph.
| Speed (RPM) | Battery Discharge | Mass (kg) | Power | Time (sec) | Acceleration (RPM/sec.) |
| 23.724792 | 153 | 0.08 | 50 | 5.058 | 4.690548 |
| 24.856242 | 139 | 0.10 | 50 | 5.391 | 4.610692 |
| 15.795495 | 139 | 0.12 | 50 | 7.576 | 2.08439 |
| 2.115704 | 194 | 0.16 | 50 | 9.847 | 0.214858 |
In conclusion from this trial, when the amount of mass in Kg was added to the pulley, the acceleration decreased. Our results this time show a negative slope in our graph (best fit line), which reflects the equation F=ma.
In the final part of our experiment, we used a ruler to measure the height of the pulley. Using Labview we looked at the relationship between battery discharge and potential energy.
For this, we used the equation PE= mgh.
After we calculated PE, we divided our result by the time (PE/T). We did this for each trial (constant mass, and constant power) Below is a graph of the relationship between Battery Discharge and PE/T along with a corresponding graph.
| Gravity (m/s²) | Mass (kg) | Height (km) | Time (sec) | PE | PE/T | Battery discharge |
| 9.8 | 0.08 | 0.04 | 5.058 | 0.158619 | 0.03136 | 153 |
| 9.8 | 0.10 | 0.04 | 5.391 | 0.211327 | 0.0392 | 139 |
| 9.8 | 0.12 | 0.04 | 7.576 | 0.356375 | 0.04704 | 139 |
| 9.8 | 0.16 | 0.04 | 9.847 | 0.617604 | 0.06272 | 194 |
| 9.8 | 0.09 | 0.04 | 4.511 | 0.159148 | 0.03528 | 111 |
| 9.8 | 0.09 | 0.04 | 2.351 | 0.082943 | 0.03528 | 139 |
| 9.8 | 0.09 | 0.04 | 1.415 | 0.049921 | 0.03528 | 110 |
| 9.8 | 0.09 | 0.04 | 1.406 | 0.049604 | 0.03528 | 70 |
The battery discharge in this part of the activity did not increase as much as we initially thought it would, but it was clear that this experiment didn’t require a huge amount of battery power. Over all, the pattern in the graph was pretty stable. This part of the experiment, however is where we saw conservation of energy between PE and the amount of energy needed on the pulley.
Over all, I really enjoyed this experiment. I learned a lot about Newton’s 2nd law and how to use the formulas used with it. This experiment was not too difficult because my partner Bryan and I were able to split the work evenly and help each other with parts we didn’t quite understand. Bryan was a huge help because I am not very exel-friendly as he was! Without his help I would have struggled on our graphs and charts. We have a very good relationship as partners and I look forward to working with him on future experiments! We try to have fun with the activities, which makes it easier for me to learn the material.
This is a picture of our pulley. This was the trial when we kept the Mass constant.