Question

A car travels with a uniform velocity of 25 m/ s for 5 s . the brakes are then applied and the car is uniformly retarded and comes to rest in further 10s . Find(i) the distance which the car travel s before the brakes are applied.(ii) the retardation,and (iii) the distance travelled by the carafter applyig the brakes

Answer 1

u=25m/sec
Distance it travels in 5sec
Distance travelled before the brakes are applied= 25*5=125m
After 5 sec brakes are applied
It then comes to rest in 10sec
u=25m/s
v=0(as it comes to rest)
t=10
a=change in velocity/time=-25/10=-2.5
s=?
s=ut+at^2/2
s=25*10+(-2.5)(100)/2=250-125
The distance it travels after the brakes are applied is 125m

Hope it helps!!

Answer 2

Answer:

u=25m/sec

Distance it travels in 5sec

i) Distance travelled before the brakes are applied= 25*5=125m

After 5 sec brakes are applied

ii) It comes to rest in 10sec

u=25m/s

v=0

t=10

a=change in velocity/time=-25/10=-2.5

iii) s=?

s=ut+at^2/2

s=25*10+(-2.5)(100)/2=250-125

The distance it travels after the brakes are applied is 125m