How does the weight of a pendulum effect its oscillation time.

Liam Kelly

How does the weight of a pendulum effect its oscillation time

Plan

The key factors that could affect this experiment are that the length of pendulum varying will change how far it has to swing to complete an oscillation.

The weight of the pendulum will have a effect on the oscillation time because the pendulum will have more weights which will increase the surface area for air resistance to take place this is the only possible way the weight of the pendulum will affect the oscillation time because, gravity is a standard force, so the weight will not effect the amount of gravity taking place.

The angle at which it is dropped at is another key factor because, if it is dropped from higher up it has longer to pick up speed so therefore it shall travel higher up giving it a longer oscillation time. If the pendulum is dropped from a lower then it shall have less time to pick up speed and so will not travel as high up on the other side.

The force at which it is released, if the pendulum is pushed it shall have gained more speed than if it was just released because it started with more momentum.

Before we carried out the experiment we did some preliminary work testing by how much we should increase the weight each time, we also tested different lengths of string to see which was most effective. We decided to increase the weight by 100g each time so we timed the weight of the pendulum from 100g to 1000g, and we decided to use 45cm of string because we thought these worked effectively.

Prediction

I predict that the more weight added to the pendulum the slower the oscillations. I think this because there will be a bigger surface area that the air resistance can act on which will decrease the speed of the pendulum. It shall loss momentum with weights.

Method

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Prediction

Method

We shall set up a pendulum using a retort stand, a G-clamp, and a set of weights, which are tied to the top of a retort stand. We shall time the weight of a pendulum from 100g to 1000g and add a 100g weight to the pendulum, after we have timed 5 oscillations, we will begin the oscillations by dropping the pendulum from a perpendicular point to the retort stand. We shall time the oscillations from the time it is dropped till it reaches the peak of its fifth oscillation, and time each weight 3 times. We are going to tie the weights to the retort stand by some string 45cm long. To keep the experiment fair we decided to use the same equipment each time and have the string attached to the same height on the retort stand, also we decided for the same person to release the pendulum and the same person to time, to try and keep consistency. We shall release the pendulum rather than push it because; it is easier to make the pendulum start with the same amount of force throughout the experiment.

Results

Analysis

My results show that an increase in weight on the pendulum the longer it takes for the pendulum to complete 5 oscillations, and my line of best fit on my graph shows a gradually increase from 8 seconds to complete 5 oscillation to 9.5 seconds to complete 5 oscillations. The reason they are close is because gravity is a standard force and is not affected by surface area or weight. So the increase in the length of time is down to air resistance, this links to my prediction. The slight difference is because the more weight we added the more air resistance occurring on the swinging pendulum, more air resistance is occurring because the front of the weights is hitting and pushing the air to the side, and with more weights there is more front of the weights and so there is more air been hit and pushed to the side and this will restrict the speed of the oscillations. We made it 5 oscillations so a difference in length of time would not be as significant as if it was a single oscillation; we repeated the experiment 3 times so we could find an average for each weight. When we put 600g onto the pendulum from 500g there was a increase in time on average to complete the oscillations by just under a second, which was possibly the anomalous result about our experiment but the times after 600g where roughly the same.

Evaluation

Our experiment I think was very reliable considering the limited resources seen as, all the times where within 1.5 seconds of each other. A regular problem that occurred in our experiment was that the pendulum would hit the bench meaning we had to restart the timing for that weight, also we dropping the weight from what we thought was the same spot but we could easily of made a mistake, we may have held it higher or lower, or we could have held it close to the stand, when the pendulum started we could have began timing to quick or late, or when it had finished 5 oscillations we could have stopped timing to quick or to late, there were many possible flaws in our test because we was going on human judgement and reaction.

We could have improved our test by having a beam and when it is broke by the pendulum the fifth time the pendulum breaks the beam it could stop timing so it would be the same reaction time for all, we could have had a stand or something to hold the pendulum in place before it is dropped that way we could be sure it was from the same spot each time.

In our experiment there was some slightly out of place results in our experiment but they’re no severe ones that could be anomalous results.

We could have investigated a further 1000g so we went to 2000g to see if after every 500g there was a jump in time of nearly a second our so, like there was in our experiment. We could also continue to the point of were we have added so much weight that it could not complete 5 oscillations to the same height as it started. We could also have tried the experiment at different temperatures to see what effect, if any it had on the oscillation times.