Acceleration is defined as the change in velocity over time so a=v/t.

Question

If you have a car that can accelerate with a=5m/s^-2, how long does it take the car to reach a velocity of v=25m/s^-1 (which is equivalent to 90km/h) ?

Show all the steps taken to get to the answer. 

Answer 1

v(t) = v₀ + at

 

If it starts from rest, v₀ = 0.  Then

 

v(t) = 0 + at = at = 5t

 

25 = 5t ⇒

 

t = 25/5 s = 5 s