# A car starts from rest and after 20 seconds its velocity becomes 108 kmh. Find the acceleration of the car.

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### 2 Answers

The formula of acceleration is:

`a = (Delta v)/(Delta t)`

where `a` - acceleration

`Delta v` - change in velocity and

`Delta t` - change in time

In the above problem, initial velocity is zero and the final velocity is 108 km/hr. So change in velocity is:

`Delta v = 108 - 0` `= 108 (km)/(hr)`

And the given change in time is 20 seconds. For the unit to be consistent, convert the seconds to hours.

`Delta t = 20 sec * (1 min)/(60sec)*(1hr)/(60 min) = 1/180 hr`

Then, substitute the values of `Delta v` and `Delta t` to the formula of acceleration.

`a =( Delta v)/(Delta t) = 108/(1/180) = 19440`

**Hence, the accelearion of the car is 19,440 `(km)/(hr^2)` .**

### User Comments

initial velocity u = 0

final velocity v=30 m/sec

time taken=20 seconds

acceleration = final velocity -initial velocity/total time taken

after calculations the final answer comes to 1.5m/sec square