Answer:4.41ms-2
Step-by-step explanation:
From rest U=0,therefore when given S=50m and V=21m/s then you apply the formula of linear motion which is V^2=U^2+2as
Then substitute for the given values and reach the answer e.g 21^2=(0)^2+2×a×50
441m/s=100ma
a=4.41ms-2