To find the time it takes for the car's velocity to reach 20 m/s, we can use the equation:
velocity = initial velocity + (acceleration * time)
In this case, the car starts from rest, so the initial velocity (u) is 0 m/s, the acceleration (a) is 2.5 m/s², and we want to find the time (t) when the velocity (v) reaches 20 m/s.
Substituting the values into the equation:
20 m/s = 0 m/s + (2.5 m/s² * t)
Simplifying the equation:
20 m/s = 2.5 m/s² * t
Dividing both sides of the equation by 2.5 m/s²:
t = 20 m/s / 2.5 m/s² = 8 seconds
Therefore, it will take the car 8 seconds to reach a velocity of 20 m/s when accelerating from rest at a constant rate of 2.5 m/s².