Question

a car is retarded by applying breakes at the rate of 2m/s square it finally stop in 10 sec ? find it's initial velocity

Answer 1

a=-2m/s sq.
t= 10sec
v=0
By 1st equation of motion,find 'u'
v=u+at
0= -2(10)
u= 20m/s
ans. u=20m/s

Answer 2

a=2m/s
t=10
final velocity=0
initial velocity=?
v-u=at
0-u=2×10
0-u=20
-u=20-0
-u=20
u=-20
.: Intial velocity=-20