Question

A car traveling at 30 m/s starts to decelerate steadily. It comes to a complete stop in 9 seconds. What is its acceleration?

Answer 1

To calculate the acceleration we use the formula,

$a=\frac{v_{f}-v_{i}  }{t}$

Here, $v_{f}$ is the final velocity of the car and $v_{i}$ is the initial velocity of the car and t is time .

Given $v_{i} =30 m/s$ and $t= 9 s$.

The final velocity $v_{f} =0$ , because car comes to stop.

Substituting these values in above formula we get,

$a=\frac{0 m/s-30m/s}{9}$

$a=3.3 m/s^{2}$

Here, acceleration is negative because car is decelerated.