What is an object’s acceleration if it is moving at 30 m/s and comes to a stop in 5 s?

Using the formula:

a = (Vf - Vi) / t

The object is coming to a stop, so the initial velocity will be 30 m/s and the final velocity will be 0 m/s. The time is 5s, as stated in the problem.

a = (0 - 30) / 5

a = -6 m/s^2

(Also, the negative sign is important because it shows a deceleration)

Answer: it will take   4.36 seconds to reach her average velocity 10.69 miles/hour.explanation:   we have equation of motion ,where s is the displacement, a is the acceleration, u is the initial velocity and t is the time taken.average velocity = displacement/ time taken.average velocity = 10.69 miles/hr = 10.69*1.6*1000/(60*60) = 4.75 m/s4.75 = s/ts = 4. 1we also have acceleration = 2.18 m/s², initial velocity = 0 m/sso it will take   4.36 seconds to reach her average velocity 10.69 miles/hour.