Question

a car travelling at 20 km per hr speeds up to 60 km per hr in 60 sec . what is its acceleration

Answer 1

$u = 20km \: per \: hour \\ v = 60km \: per \: hour \\ t = 60 \: seconds \\ a = \frac{v - u}{t} \\ = \frac{60 - 20}{60} \\ = \frac{40}{60} \\ = \frac{2}{3} \\ = 0.6...........$
$so \: acceleration \: is \: 0.6m \: per \: second {}^{2}$

Answer 2

u=20km
v=60km
t=60sec
acceleration=v-u/t
a=60-20/60
40/60
2/3