Question

define acceleration give its unit a bus starts from rest attains a velocity 72 km per hour in 5 seconds find the acceleration

Answer 1

the rate of change in velocity is called acceleration unit of acceleration is metre per second square now,here is the solution of your question.
this is the answer of your question

Answer 2

the rate of change of velocity is called as acceleration
unit m/s^2
velocity=72×5/18=20m/s
time=5s
acc=v-u/t=20-0/5=4m/s^2