GPE Sand Crater CEE By Mason Rounds


My claim is that if I drop a bigger mass into the sand, then the mass will impart more Joules of energy to the sand, leaving a bigger crater. Likewise, if I drop a weight of equivalent mass from a greater height, it will impart more Joules of energy to the sand, thus leaving a bigger crater.


My evidence for the claim about mass is that in our expirement, it seems to be a general rule that the more mass a weight has, the higher its GPE and the bigger the crater it left, and the same applies to height. (There are, however, some aberrations. More on those in the errors section below.) For example, when the weight's mass was 10 grams, and being dropped from .5 meters, its GPE was .049 J and it left a crater 0.1 CM deep. When we increased the mass to 20 grams, it had a GPE of 0.98 J and its crater was 0.5 CM. The same goes for height; when a 50 gram weight was dropped from .1 meters, it had a GPE of 0.49 J and left a crater 0.1 CM deep. When the same weight was dropped from 0.2 meters, the GPE increased to 0.98 and the crater was 0.3 CM deep. Here are some graphs of our data; the top one is mass vs. GPE and the bottom graph is height vs. GPE.


This is my explanation for this claim and evidence. On my worksheet for potential energy, (located on page 33 of my notebook) it states that an object's GPE is defined by its weight and height in the air. Weight, of course, is simply an object's mass times the force of gravity at that location, so GPE really depends on an object's mass, height, and the force of gravity, which never changes while on earth. In other words, GPE=mgh. As such, increasing the object's mass or height while keeping other quantities the same will linearly increase the GPE, as shown in the graphs above, because no quantity matters more in the equation than any other.


Despite our best efforts to prevent any errors during this lab, there is a fairly good chance that some slipped through. For example, when we were testing for mass, we had to start using different-shaped weights, because other people had begun to test with the set that we were using. These weights were thinner, but had a larger radius, which no doubt affected their aerodynamics when falling and the shape of their crater. Therefore, our GPE was the same for all of these weights, but it made the crater sizes vary a large amount. Another thing that may have caused errors is our pan of sand. When I measured it, the depth of the sand in the pan was no more than three CM deep, which may have made some of the craters smaller. There could also have been the usual human errors regarding consistency in measurement and dropping.

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