Solution to problems – class 9 – Set 1 Q 18

Problem Statement

A car starts from rest and accelerates uniformly over a time of 7 seconds for a distance of 98 m. Determine the acceleration of the car.

Solution

Distance travelled: S = ut + ½ a t²

As u = 0, the equation becomes    S = ½ at²

 so, a = 2S/t² …..(1)

t = 7 seconds
S=98 m    

 

from eqn   1 we get acceleration a = 2S/t²
= (2 * 98)/7² =4 m/s²