d A car starts from rest - job exam mathematics

# Kinematics Numerical 3( A car starts from rest )

Kinematics Numerical 3: A car starts from rest. Its velocity becomes 20 ms in 8 s. Find its acceleration.

Solution:

## A car starts from rest …

Rate of change in velocity is called acceleration(i-e change in velocity w.r.t time is called acceleration) . Here the initial velocity of the car is zero because car was at rest initially! The final velocity of the car is 20 meters per second.

Let;s arrange the given data as under;

Initial velocity =Vi= 0 m/sec

Final velocity=Vf=20 m/sec

Time =t= 8 sec

Acceleration=a=?

We get change in velocity as

$\triangle V=Vf-Vi=20-0=20 \frac{m}{sec}$

We divide this change in velocity on time taken to get the rate of change of velocity — or simply to get the acceleration !

i-e

$a=\frac{\triangle V}{t}=\frac{20}{8}=2.5\frac{m}{sec^2}$

So , the acceleration is 2.5 meters per second square

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