Natural Science Unit 30 Laboratory Activity: Falling Bodies II
Goal: Explore how changing mass changes force when objects are under the same constant acceleration, in this case, acceleration due to gravity near the surface of the Earth.
Materials and Equipment:
- Several small items of equivalent size and shape but different masses. Some suggested possibilities are:
- Glass marbles and plastic balls of the same size
- Pill box into which you can put pie weights
- Wheat, corn, or other flour
- Flour sifter
- Bowl big enough to hold flour and your item
- Knife or ruler with a straight edge
- Clean, dry, cookie sheet, cutting board or other flat, smooth surface
- Measuring stick or tape, preferably graduated in millimeters
- Scale to measure weight, or some method of calculating weight.
- Sift flour until bowl is full; use a straight-edge to level the surface.
- Place the bowl on the cookie sheet or cutting board. Be sure that this surface is dry, so that any flour you recover between trials does not become sticky.
- Measure a height 10-15 inches above the bowl and mark it somehow so that each trial begins at the same height.
- Drop your lightest object from this height into the bowl. (Flour will splash out of the bowl).
- Measure the diameter and depth of the "crater" produced as best you can. Record your measurements and describe as well the shape of the crater ("wide and shallow", "narrow and deep", etc.).
- Repeat the trial the the same object at least three times.
- Repeat the experiment with at least two more different masses. If you are using the pill-box and weighting it, double and then quadruple the original weights for your second and third trials.
Please be sure that your report contains the following:
- A description of the actual materials you used.
- A description of your procedure in sufficient detail that another student would be able to repeat your experiment.
- A table of your data, including weight information, depth of crater, diameter of crater, and description of crater shape, along with any other observations you made. You should have at least three trials for each of three weights.
- Analysis of data. Does the depth of the crater increase in the same proportion as the increase in weight?
- A conclusion: is the force (measured in terms of the work done in producing the crater) proportional to the weight?
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