Question

While working on a roof, Rob dropped his hammer. The hamer's fall can be represented by the equation h=-16t^2+20 (where t=time in seconds and h=height in feet) How long will it take the hammer to reach the ground?

Answer 1

It will take 1.12 seconds for the hammer to reach the ground.

Explanation:

The height of the hammer after t seconds is given by the following equation:

`h(t) = -16t^(2) + 20`

How long will it take the hammer to reach the ground?

This is t for which h(t) = 0. So

`h(t) = -16t^(2) + 20`

`-16t^(2) + 20 = 0`

`16t^(2) = 20`

`t^(2) = (20)/(16)`

`t^(2) = \frac{1.25}`

`t = \pm √(1.25)`

Time is a positive measure, so

`t = 1.12`

It will take 1.12 seconds for the hammer to reach the ground.