Aplane accelerates at 30 ft/s squared for 3.0 s. find it’s increase in speed in mi/h. i am stuck on that problem.

So: Acceleration is related to velocity by-

Where v is velocity and t is time. (Note that there should be a delta symbol by velocity as the change in velocity is what produces an acceleration)

So we know the acceleration but we have to convert units.

Now there is really two ways to do this, you can just plug this into google or you can do dimensional analysis. Ill show you dimensional analysis.

So we have

We need mi / h so we need to convert feet to miles and seconds to hours like so:

Where there are multiplication signs in between each term there, so we end up with:

So in mi/h we get 20.45 mi/h

Now we need to apply the formula:

a = v/t

So:

v = at

v = (20.45)(3)

v= 61.35 --> so the change in speed is 61.35 mi/h over the 3 second time period.