We calculate acceleration with the formula, a=
. So subsitute the values in the formula, so it's
. We need to multiply it by
because the speed is 15 second and we need to convert it to hour. 72-54 is 18 and multiplied by 60 is 1080. Then divide it by 15 which is 72 km/hr. Your answer will be 72 km/hr :).
Hope it helped!