Question

Maria is painting the trim on the top of a building. She drops her paintbrush. The paintbrush has a velocity of 29.4 m/s when it hits the ground 3 s later. What is the acceleration of the paintbrush?

Answer 1

`a=9.8m/s^2`

Explanation:

Use the formula `a=(v_f-v_i)/(t_f-t_i)` where `a` is the acceleration, `v_f` the final velocity, `v_i` the initial velocity, `deltat` the change in time, which can also be written as `t_f-t_i`.

3 seconds later suggests that the change in time was 3 seconds.

The final velocity is 29.4m/s

The initial velocity is 0 because that was the velocity of the paintbrush just as it started its descent.

Therefore,
`a=(29.4-0)/3`
`a=9.8`

This is the speed of acceleration due to gravity on Earth. Initially, you could've solved it by looking at it but I wanted to give you how to work out answers like this.