Gravity and the Simple Pendulum.

We Rearranged the equation T=2π√l/g into g=4π²*l/T² and substituted the length (m) and time (sec 10 back-and-forth swings) into the equation so that we could find our value of ‘g’ for each trial.

10. We added up our three values for ‘g’ and divided the total by 3.
11. We found out the %correctness for each of our three values of ‘g’ and divided it by 3 to find out the average %correctness of our value for ‘g’.

 

Controlled Variables:                                        Uncontrolled Variables:

Mass, length of string,                     Wind and stairwell.

and the displacement.                   

Results:

Determining the Acceleration of Gravity

As you can in the results table I included a category for percentage error. I included this category in my results’ table so that I could find out how correct our value for ‘g’ is. Our value of ‘g’ was 1% incorrect.

Discussion:

In order to find an accurate value of ‘g’ we needed to change the equation T=2π√l/g to g=4π²*l/T² then we substituted the length (m) and time (sec) into the equation g=4π²*l/T². Which gave us the value for ‘g’ as 9.73(m/sec²).

This is how we rearranged the equation to get the value for ‘g’ as 9.73(m/sec²):        T=2π√l/g

T²=4π²*l/g

T²*g=4π²*l

g=4π²*l/T²

During the experiment we had a problem with our pendulum because it kept on hitting the edge of the stairwell as we gave the pendulum a push. So we tried to decrease the force we pushed the pendulum with, although it still hit the edge of the stairwell on the first few swings. Also, it was difficult to measure the length of the pendulum since it was 7 metres long. We also forgot that we had to measure from the pivot point to the center of gravity of the mass.

Conclusion:

Our results prove that our value of ‘g’ is 1% incorrect, this is quite accurate. Although during the experiment I think we did not measure the length of the pendulum correctly because we did not measure from the pivot point to the center of gravity. We also did not record the period properly because we recorded the period knowing that the pendulum kept hitting the stairwell, when the pendulum hit the stairwell it delayed the period. These two variables probably led us to the incorrect value of ‘g’. As an improvement for next time we do this experiment we could measure the length of the pendulum by measuring from the pivot point to the centre of gravity. We could also make the length of the pendulum shorter so that we don’t have as much trouble measuring the pendulum and try to do the experiment somewhere where the pendulum won’t hit something.