Question

What is an object's acceleration if it is moving at 30 m/s and comes to a stop in 5 s?

Answer 1

The object's acceleration is `"-6 m/s"^2"`.

Explanation:

Remember:
`a = (∆v)/(∆t)`
and

`∆v = v_f - v_i`

So, in this case:
`v_i = "30 m/s"` [fwd]
`v_f = "0 m/s"` (it comes to a stop)
`∆t = 5s`

Thus,
`a = (∆v)/(∆t)`

`a = (v_f - v_i)/(∆t)`

`a = (-30 m/s)/("5s")`

`a = "-6 m/s/s" or "-6 m/s"^2"`