2. If a car accelerates uniformly at a rate of 4.0 m/s2, how long will it take to reach a speed of 20
m/s, starting from rest?

The car will take 5 seconds

Explanation:

Constant Acceleration Motion

It's a type of motion in which the velocity of an object changes uniformly in time.

If the object starts from a speed vo during a time t with an acceleration a, then its final speed is:

The car is accelerating at a rate of a= 4~m/s^2 and reaches a speed of vf=20 m/s starting from rest (vo=0).

From the equation shown above, we solve for t:

t = 5 seconds

The car will take 5 seconds