##### Compute the value of gravity g by measuring a free fall

###### Author :

#### FizziQ

##### Context

Galileo is the first to document that the distance an object travels during a fall is proportional to the square of the elapsed time. It thus determines the value of the earth's gravity. The student reproduces this experience on his laptop. He or she measures the time it takes for an object to fall by recording the values of linear acceleration measured by his or her smartphone. He or she deduces a value for weightlessness from the hourly equation of free fall.

##### Sample protocol for the student

###### 1. Determine the value of gravity, g

2. Galileo is the first to document that the distance an object travels during a fall is proportional to the square of the elapsed time. It thus determines the value of the earth's gravity

3. What formula gives the height as a function of time in the case of a fall without initial velocity?

4. Find a very soft pillow on which you can leave your cellphone without damaging it at a height of 1.50m

5. By dropping your phone upright from this height on the pillow, record the linear acceleration Y

6. Can you determine on the graph the beginning and the end of the fall?

7. How can you deduce the constant of gravity g from this?

8. Perform several experiments to confirm the value you find, and compare it to the result you know.

9. Document your hypotheses, results and conclusions in your experiment notebook by adding text and photos

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