# Determine acceleration of gravity through experiment?

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1. Sep 5, 2014

### Henrybar

I am asked to determine the force of gravity(9.8 m/s^2) through an experiment which I will conduct. My recourses are very limited and so cameras and accelerometers are out of the question.

I have come up with a basic experiment which might work, but I would like reassurance from the forum.

Experiment: Using a ticker timer, attach one end of the paper to an object with the dimensions of an eraser(to prevent bouncing, rolling). The object will remain at the very edge of a table top until dropped. Once dropped, the ticker timer strip of paper should contain sufficient data to derive the variable of time; the displacement can be easily obtained from the height of the table. Now that I have known values for t, Δd and Vi(0), can't I substitute them into the linear motion equation a=(2Δd)/Δt^2) to find the acceleration due to gravity?

Will it work? What do you suggest I do to get closer to 9.8 m/s^2?

2. Sep 5, 2014

### olivermsun

Is the purpose to demonstrate a measurement of gravity or to get the most precise measurement you possibly can?

3. Sep 5, 2014

### BiGyElLoWhAt

What if you didn't rely on something falling, but you relied on something rolling down a slope? You would get a constant which you would know (depending on the angle) times g. There's a book you should check out; it's called the 10 most beautiful experiments. Read the first one in there and maybe you can get some ideas from that. That's actually where my suggestion came from.

4. Sep 5, 2014

### Quantum Braket

Why not use a string with a weight in the end (pendulum?)

5. Sep 5, 2014

### Henrybar

olivermsun - the purpose is to demonstrate that 9.8 m/s^2 is in fact the acceleration due to gravity. As long as the experiment achieves a number close to 9.8 and is repeatable, then it is fine.

6. Sep 5, 2014

### Staff: Mentor

Are you allowed to use a scale? Let's see, a liter of water weighs...

7. Sep 5, 2014

### Staff: Mentor

Or maybe just use a spring with a known spring constant instead of a store-bought scale...

8. Sep 5, 2014

### olivermsun

The rolling ball and pendulum experiments mentioned by two posters above are very good for generating accurate and repeatable measurements. Anything that allows you to time the motion over a long period of time will help you reduce timing errors.

For your amusement: there is actually an iPhone app that uses a camera to time the oscillation period of a tennis racket/golf club over many periods (for weighting/balancing the racket).