Question

a car traveling at 7.0 m/s accelerates uniformly at 2.5 m/s^2 to reach a speed of 12.0 m/s how long does it take for this acceleration to occur?

Answer 1

Hello there,

In the case of a problem that explicitly describes constant acceleration, you are going to need use one of four equations that are valid for motion under constant acceleration. In most physics text books, these equations will be in the second or third chapter, and they should be grouped together in a nice accessible box somewhere. Its a good idea to memorize these right away, as the constant acceleration problems are very common and these equations will be used for many more chapters through the course. (At the very least, memorize the page where you can find them quickly, cuz you will need them!)

In this case, we are interested in the equation that uses the initial velocity (7.0 m/s), the acceleration (2.5 m/s/s), and the final speed (12.0 m/s). The equation that fits these known data and has one unknown to solve for is:\[v _{f}=v _{0}+at\]Plug your values in for the variables and solve for t.

Answer 2

That is correct.
(12m/s-7m/s)/2.5m/s^2=t=2s