Consider a car moving on a straight road with a speed of 100 m/s. The distance at which a car can be stopped is : (μ_{k} = 0.5)
(a) 800 m
(b) 1000 m
(c) 100 m
(d) 400 m
b) is the correct option i.e. 1000
When the car is stopped by friction then its retarding force is
ma = μR
ma = μmg
a= μg
Consider the equation v^{2} = u^{2} -2as (the car is retarding so a is negative)
0 = u^{2} -2as
2as = u^{2}
s = u^{2}/2a
s = u^{2}/2μg
s = (100)^{2}/2 x 0.5 x 10
s = 1000 m