Question

A vehicle with a mass of 2 tons travels on a horizontal road at a speed of 126km/h.The driver notices a donkey at the side of the road and decides to reduce speed. The brakes are applied and the vehicle slows down to 72km/h after 5 seconds. Calculate the acceleration of the vehicle.

Answer 1

First change the speeds to m/s.
126 km/h = 35 m/s
72 km/h = 20 m/s
Speed change = 20 - 35 = -15 m/s
Acceleration = (speed change)/(time)
= -15/5 = -3.0 m/s^2

Answer 2

How do you convert 126km/h to m/s