Answers

2014-06-08T17:04:56+05:30
The initial velocity(u) of the car is = 54km/hr = 15m/s
The final velocity(v) of the car is = 0 m/s
The time taken(t) by the car to come to rest = 90 seconds 
We must find the acceleration(a) and displacement(s) covered by the car
From v = u+at .we find acceleration of the car .
By substituting in the equation we get 
0 = 15 + a(90)
a = - 15/90
a = -1/6 m/s²
The displacement of the car is given by 
v²-u² = 2as
0²-15² = 2*(-1/6)s
225 = (1/3)s
s= 225*3 =675 m.
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2014-06-08T18:30:36+05:30
Initial speed = 54Km/h = 54*5/18 = 15m/s
finial speed = 0
time = 90s
v = u + at
0 = 15 + 90a
a = -1/6
let distance = s
v² = u² + 2as
0 = 15² - 2*1/6*s
s = 225*3
s = 675 m

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