Reaction time of a driver is the time interval between the moment the driver sights an obstacle and the moment he applies the brakes. During this time the car travels with a constant speed at which he is driving and gets nearer to the obstacle. A driver has a reaction time of 0.5 s and is travelling at 72 kmph on a straight road. What should be the minimum deceleration produced by the brakes of his car if he should avoid hitting an obstacle 50 m away from the car at the moment he sees it.
A) 5m/s C) 3m/s D) 2ms
Answers
Answered by
3
Answer:
5m/s
this is the correct answer of this question
Answered by
4
Answer:
5ms^-2
Explanation:
Given,
Reaction time = 0.5s
u ( initial velocity) = 75kmph = (75*5/18)m/s = 20m/s
v (Final Velocity) = 0m/s
S (displacement) = 50 m
Distance travelled before the driver started to apply brakes
=> V = S/T
=> S = VT
=> S = 20*0.5
= 10m
So, Distance travelled before stop, 50-10 = 40m
now apply to 3rd equation of motion
=> v2 - u2 = 2as
0 - (20)^2 = 2.a.40
=> -400/80 = a
a = 5ms^-2
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