IIT JEE , AIEEE Forum - Physics , Mechanics

piyushsahani

the speed limit of a car on road is 45km/hr . the car stops moving a distance of 5m .a police man arrested the car driver for speeding .the condition is that the deaccelaration of the car should not be mor than a freely falling body(i.e 10m/s²) find eether the car driver was arrested for right cause or not.

sankydreams

45km/h = 12.5 m/s

look since the car stops its final velo = v =0
dist = 5m
let initial velo = u
let accn = -10
using third eqn of motion
u^2 = -2as = 20 * 5 = 100
=> u =10
this means that even if the car wud have deaccelerated with max acceleration, its initial velo is < 12.5
hence the driver was arrested for wrong cause
rate if this helps u...

snandkeolyar

Let the car be travelling at 45 km/h=25/2 m/s
u=25/2 m/s
v=0
s=5m
therefore v^2-u^2=2as
=>a=(0-625/4)/10
=>a=-15.625m/s^2
deceleration=15.625m/s^2 which is more than 10 m/s^2
therefore the man is arrested for the right cause.

sankydreams

hey shobhit the driver is to be arrested for speeding not for deaccelerating, so ur soln is incorrect..

rshm15varma

I'll go with sankydreams....becoz I also solved the question in the same way..

abhi_iit000

u all r big stupids............

sankydreams

and y in the whole world did u think so??????
if u can solve this better, then cmon post ur damn solution

snandkeolyar

I think the legacy here is for deaccelerating at a rate less than 10m/s^2 and not for speed

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