The Effect of Weight on the Amount a Fixed Dowel Deflects
How weight affects the amount a fixed dowel deflects.
Labelled diagram of proposed set up:
When reading off the ruler, it is necessary to crouch otherwise
parallax will occur and readings will be inaccurate.
There are 4 independent variables in this experiment. The thickness of
the dowel, the weight being hung from the dowel, the distance the
weight is being hung from the dowel and the amount of over-hang of the
dowel. These will produce a dependent variable, the bend/deflection of
the dowel. I will use the weight being hung as my independent
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The equation for moment was cited from Tom Duncan's GCSE Physics book
I did the experiment exactly how I planned out earlier, with the
exception of adding some double-sided adhesive tape to the rod so the
weight would not slip down the rod whilst reading the amount of
I made sure that all unused weights were placed away from the table
edge so they would not fall onto my foot. I also made sure that no
more than 500g was put onto the rod in case it were to snap and a
splinter were to come into my eye.
Analysis and Conclusion
Conclusion (eg relationship between variables as given by graph)
I have to come the conclusion that the more weight added to the dowel,
the more it will deflect. Looking at the graph, it appears that the
relationship between the two variables is linearly proportional,
seeing as the line of best fit does not pass through the origin.
Scientific explanation of results (including comparison with
prediction, where appropriate):
In the planning stage, I predicted that the relationship between the
two variables would be directly proportional, but given that the
conclusion that the relationship is linearly proportional, it shows
that my prediction was wrong.
If you consider the dowel to be like a spring, it is easier to see why
the results are proportional. If the top half of the length of the
dowel is under tension when being bent, and the bottom half is under
compression, like Hooke's Law, a spring will extend or shorten if