A certain car is capable of accelerating at a rate of +0.90 m/s2. How long does it take for this car to go from a speed of 50 mi/h to a speed of 65 mi/h?

Answer 1

Use the formula (change in V) = a t

But first you must convert the mi/h (mph) speeds to consistent metric units of m/s.

The 15 mph speed change corresponds to 22 ft/s or 6.71 m/s

(I have always found it convenient to remember that 15 mph is 22 ft/s, and 1 ft/s = 0.3048 m/s, exactly)

Time required = (6.71 m/s)/(0.90 m/s^2) = 7.45 seconds