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)` .