Please write your answer electronically or with a clear handwriting. Here\'s the
ID: 1569084 • Letter: P
Question
Please write your answer electronically or with a clear handwriting.
Here's the whole lab, if you want to see the questions:
http://www.phys.ttu.edu/~batcam/Lab%2012%20Periodic%20Motion.pdf
In the periodic motion lab, you measured the effect of mass, length, and angle on the period of a pendulum. To measure the effect of one of these variables, the other two were held constant. Briefly explain why. To determine which variables affected the period, you compared results for small, medium, and large values of the variable you were testing. When taking data, you were asked to average three measurements each for the small, medium, and large values. What is one possible reason you were asked to average three values instead of two?Explanation / Answer
1.
Consider a simple pendulum which is composed of a compact weight (bob) that is hung from a string attached at its upper end to a fixed support. Suppose the goal of the investigation is to determine which variables influence the period of the pendulum, that is, the time for the bob to execute one complete cycle over and back. Some variables whose influence one could investigate include the length of the string, the mass of the bob, and the angle from the vertical at which the string is released. The latter three variables are termed independent variables, because one selects their values in carrying out the experiment. The period is termed the dependent variable, because its value may depend on the values of the independent variables.
In order to determine how each of the independent variables may influence the period, one needs an experimental design in which only one of the independent variables is changed at a time while the others are held constant. In this way, if an influence (or lack thereof) is found on the period, one can be fairly confident that the independent variable that was changed is the variable that influenced (or didn't influence) the period. Such an experiment is called a controlled experiment. The reason we said fairly confident is because there's always the possibility in dealing with the natural world that there are variables that the experimenter has overlooked and has not controlled.