A car travelling 70km/h east changed its velocity to 90km/h east in 4.5s. Determine the magnitude and direction of the average acceleration of the car in m/s2.

Question

I don't know how to find the magnitude, Please help

Answer 1

just as speed is distance/time,
acceleration is velocity/time, or
(90-70)/4.5 = 4.44 km/hr/s * 1000m/km * 1hr/3600s = 1.2345 m/s^2