Question

A car starts from rest and accelerates uniformly to a speed of 72 km. p.h. over a distance of 500 m. Calculate the acceleration.

(a) 0.3 m/s^2

(b) 0.4 m/s^2

(c) 0.5 m/s^2

(d) 0.6 m/s^2

The question was asked by my school principal while I was bunking the class.

The doubt is from Numericals On Kinematics Of Motion in portion Kinematics & Kinetics of Motion of Machine Kinematics

Answer 1

Correct answer is (b) 0.4 m/s^2

For explanation: Given : u = 0 ; v = 72 km. p.h. = 20 m/s ; s = 500 m

First of all, let us consider the motion of the car from rest.

Acceleration of the car

Let a = Acceleration of the car.

We know that

v^2 = u^2 + 2as

or, 20^2 = 0 + 2a x 500 = 1000a

or, a = 20^2/1000 = 0.4 m/s^2