Question

A car covers 200 meter in 20 seconds after starting from rest with a constant acceleration. Find the acceleration.
1. 2 m/s²
2. 4 m/s²
3. 0.5 m/s²
4. 1 m/s²

Answer 1

Correct Answer - Option 4 : 1 m/s²

Concept:

Acceleration: The rate of change of velocity is called acceleration. 

Equations of Motion

The equations of motion establish the relationship between acceleration, time, distance, initial speed, and final speed for a body moving in a straight line with uniform acceleration.

The equations are

v = u + at - (1)

\(s = ut + \frac{1}{2}at^2\) - (2)

v2 = u2 + 2as - (3)

v is final velocity, u  is initial velocity, t is time, a is acceleration, s is the distance travelled. 

Calculation:

Initial speed u = 0 (Started from rest)

distance travelled s = 200 m

time taken t = 20 sec

acceleration a = ?

Using the second equation

\(s = ut + \frac{1}{2}at^2\)

\(\implies 200 = (0) t + \frac{1}{2}a(20)^2\)

a = 400 / 400 = 1 m s^{- 2.}