Question

If a coin is dropped from a height of 80 m, how fast will it be travelling when it hits the ground? What assumptions, if any, do you need to make?

Answer 1

`v_f=`-`40m/s hatj`

Explanation:

In case of free fall

`v_f=sqrt(2*g*h)`

so `v_f=sqrt(2*10*80)`
`v_f=40m/s`.

we didn't assumed anything .

The derivation of the equation is from 3rd equation of motion.