# Experiment to Find Acceleration due to Gravity

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Introduction

### Experiment to Find Acceleration due to Gravity

Aim

The aim of my experiment is to measure the earth’s gravitational field strength, which is also the acceleration due to gravity. This involves mass, which is the amount of matter an object contains and weight which is the force of gravity pulling down on an object with a mass. Mass is measured in Kg and weight is measured in Newton’s. Gravity is the weakest of the four fundamental forces, yet it is the dominant force in the universe for shaping the large scale structure of galaxies, stars, etc.

The earth’s gravitational field strength is calculated by the weight (N) / Mass (Kg), therefore the earth’s gravitational field strength (g) is measured in (N/Kg). As an object is in free-fall it accelerates at the rate of g.

Hypothesis

Isaac Newton firstly discovered gravity when an apple fell on his head. He then discovered that every object has a mass and that two masses attract each other. This attraction has a gravitational field strength, Isaac Newton discovered that g = 9.81 N/Kg. This is now a well now fact and is accepted as the earth’s gravitational field strength.

Definitions

Gravity Force

Middle

Conclusion

I have concluded from my results that the gravitational field strength of the earth is 9.8 N/Kg. This is only accurate to two significant figures because of the limitations of quality and accuracy of the experiment. If I were to use more accurate equipment I would probably be able to show that the gravitational field strength of the earth is 9.81 N/Kg, though human error in implementation and calculation of the results.

Although I have not found g = 9.81 N/Kg, I have found that my results does fully support the result of g = 9.8 N/Kg. To find “g” I had to find the gradient of the line on the graph, the line on the graph was not a line of best fit, but a line which goes through all the points on the graph which means there are no odd results that may throw off the reading of g partially. There is a full positive correlation, which shows that the experiment was carried out accurately each time the experiment was done and a reading was taken.

My results show and prove that my prediction and scientific knowledge were accurate. I have proved Newton’s theories on gravity using a different experiment to the one he did.

Conclusion

Overall I feel that the experiment was suitable as it did allow me to find “g” accurate to two significant figures so the limitations of the apparatus and error causing factors were not too great as the effect they had was minimal.

The clock would measure the time and all I would have to do is measure the displacement and then putting these two measurements in the formula, g = 2S/t^2, would provide me with the earth’s gravitational field strength. I could also have used the original pendulum experiment that Isaac Newton used but I found that it would be even harder to measure than the original experiment, meaning it is likely to be very inaccurate when I try to calculate the results.

As my results came to g = 9.79 N/Kg, which is only off 0.02 N/Kg, I am sure that If I were to rectify the recognised causes of error I would easily get g = 9.81 N/kg. I also believe that the results were off because the trolley wasn’t in free-fall; it had a considerable amount of friction and air resistance acting against it. The steel ball from the trap door experiment would be in free-fall as there would be no friction acting against it and the air resistance would be a lot less than that acting on the trolley.

This student written piece of work is one of many that can be found in our AS and A Level Mechanics & Radioactivity section.

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