A car starts from rest and accelerates to a speed of 72 km/h in 5 seconds. Assuming uniform acceleration, what is the acceleration in meters per second squared? A ball is thrown straight up witha speed of 36 m/s. How long does it take to return to its starting point? Barbara travels 20 km Northward, then travels 40 km Eastward, then continues for 50 km in a Southward direction. What displacement will now take her back to her initial position?