Physics ATAR Experiment - Newton's Second Law

16 Mar 2019 in Hydejack

In Physics we recently did an experiment in regards to Newton’s Second Law. I’m going to show you my report for it. Enjoy!

Liam Arbuckle – Physics 2019 – Newton’s Second Law Experiment

Aim: Look at the speed of a trolley with weights on it in regards to Newton’s Second Law. Newton’s second law can be described as follows: The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object. Hypothesis: The more weights that are on the trolley the faster it will move. Equipment & Materials: • Weights – 10 50g circular weights • Trolley • 1 metre-long ruler • 1 desk • Clamp • Stopwatch/timer • String Method:

1. Attach the clamp to the end of the table
2. Move the ruler to the edge of the table, with the 0cm being at the end of the table
3. Measure out 100 cm of string, and cut
4. Loop string around the hook on the clamp and the weights holder
5. Attach the other end of the string to the trolley
6. Move the trolley back so that the end of the string is above the 50 cm line from the ruler
7. Attach weights to the weights holder and the trolley, and time how long it takes for the trolley to hit the clamp

Results: Time (seconds) Mass (grams) Test 1 Test 2 50 1.02 1.29 0.97 1.31 1.08 1.05

100 0.78 0.82 0.74 0.7 0.82 0.8

150 0.76 0.83 0.77 0.74 0.78 0.77

200 0.7 0.69 0.74 0.72 0.75 0.73

250 0.67 0.64 0.69 0.71 0.7 0.73

Discussion In both tests, when there was a heavier mass on the trolley, the trolley moved faster. In the first test, I handled the stopwatch and Farid released the trolley. In the second test, both Farid and I handled the stopwatch and the results for the second test were the averages of both of our results. Apart from in test 1 – where my results were way under the test 2 results – the results from both tests were relatively close together. Since there were few outliers, this suggests that there was minimal uncertainty, perhaps plus/minus 0.3 of a second. The results showed that the acceleration of an object as produced by a net force (the weights measured in newtons) is directly proportional to the magnitude of the net force. The net force when there was a 250g weight attached was 250 newtons downwards. The trolley moved 50 cm in 0.68 seconds (as an average) in the first test and 0.69 seconds in the second test. The average acceleration of the trolley is therefore F=MA, which we can rearrange to be A=F/M, F being 250g and M being the mass of the trolley. The trolley’s average acceleration was 2.1004 metres per second per second. Therefore the mass of the trolley is 525.1 grams, and the force exerted was 525.1 newtons. When the mass of the weights was 200g, the average time taken for the trolley to move 50 cm was 0.72 seconds, so the average acceleration would be 1.929 metres per second per second, making the force exerted around 340 newtons. Conclusion If I could have done the experiment again, I would have measured the weight of the trolley as well. However, as I mentioned above, there is minimal uncertainty in the time taken for the trolley to move the 50 cm, and when we look at the equations, we can see that it does indeed follow Newton’s second law. To reduce the uncertainty more, I would have done more tests and have had more people manning the stopwatch.