Simple Pendulum To Determine Acceleration Due To Gravity
[..........So, if you can manage a stand, a bob and a string, it is just a matter of time to do the experiment.]
Simple pendulum is a weight suspended from a certain height which can move freely back and forth. If the angular displacement of a simple pendulum is not more than 4 degrees than we can use it to determine the acceleration due to gravity. It is because acceleration due to gravity, which is g, depends upon the length and time to complete a complete cycle of the pendulum. Now, we can measure the height of the pendulum and also we can measure the time taken by the pendulum to make one complete cycle. What we need to know now is the relation between g and these two quantities. The relationship is as follows,
So we can measure time, T for different length, L, of the
thread/string of the pendulum. Now plotting them on a graph we can find average
L/T*T, hence g. The process is pretty simple but this is a very important thing
cause if we know g, and the radius of the earth we can measure the mass of the
earth and a lot more.
Those who are just feeling little bit interest in physics,
specially the students of countries like Bangladesh, India can do the
experiment and determine g by their own. It is interesting and easy to do. You
don't need any special instruments except the stop watch; stop watch is also
within your reach. Any mobile phone is provided with stop watch now-a-days.
What else is needed is a bob and a string. string is very easy to collect and
you can make the bob with a tennis ball. just add a hook with tape to the ball
so that it can be suspended. Now measure the length of the string with a scale.
Remember you have to measure from the point of suspension to the center of mass
of the ball (bob).
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