Question

A body travelling at a velocity of 30m/s in a straight line is brought to rest by the application of brake. If it covers a distance of 100m during this period find the retardation

Answer 1

u= 30m/s
V=0
S=100m

Now using
V²-u²=2as
0²-30²= 2×a×100
-900/200= a
a= -4.5m/s²

Answer 2

u=30m/s
v=0
s=100m
a=?
using third equation of motion
2as=v x v -u x u
2a x 100=0 x 0-30 x 30
200a=-900
a=900/200
a=9/2=4.5metre per second square