physics
posted by kyle .
Hello can you please help me with this investigation. I am having lots of problems with it can you please help.
Thandeka wanted to investigate whether the number of vibrations per second depended on the length of the pendulum string. She sat up the apparatus. She pulled the string with the mass piece sideways to position A, which is about 20cm from position B, and allowed it vibrate whilst counting the vibrations in 30 seconds.
1) Write one term for number of vibrations per second.
2) Formulate an appropriate problem question for the investigation.
3) Identify the: independent variable. Dependent variable.
4) Name one variable that Thandeka should keep constant during the investigation.
5) Write down a suitable hypothesis for her investigation.

(1) you can call the number of vibrations per second, f.
(2) You want to know how f depends upon m, the string length, L
(3) The independent variable is L.
(4) You should also keep the mass M the same. Keep the deflection angle the same also. That means that, as the length changes, the mass will be pulled different distance from the equilibrium position.
(5) The results might sjuggest that the frequency is inversely proportional to L^(1/2)
Athough the experiment will not show it, f is independent of M and slightly dependendent upon the angle A. Those two parameters would have to be varied separately to verify this.