Question

To determine freefall acceleration on a moon with no atmosphere, you drop your handkerchief off the roof of a baseball stadium there. the roof is 113 meters tall. the handkerchief reaches the ground in 18.2 seconds. what is freefall acceleration on this moon? (state the result as a positive quantity.)

Answer 1

Take the starting position 113 m above ground to be the origin, and the downward direction to be positive. Then the vertical position
`y` of the handkerchief (ignoring air resistance due to the absence of an atmosphere) at time
`t` is

`y=\frac12gt^2`

where
`g` is the acceleration due to gravity on this moon. We have

`113\,\mathrm m=\frac g2(18.2\,\mathrm s)^2\implies g=12.4\,(\mathrm m)/(\mathrm s^2)`