a car which weight is 1000N is travelling at 90kmn/hr and come to rest in a distance of 50m after applying the brakes. assume uniform acceleration, calculate how large its stopping force was exerted by the friction between the wheel and the road.

Answer 1

90,000 meters / 3600 seconds = 25 m/s=Vi

v = Vi + a t
0 = 25 + a t
so a t = -25 and t = -25/a

d = Vi t + .5 a t^2

50 = 25 (-25/a) + .5 a (625/a^2)

50 = -625/a + .5 (625/a)

50= -625/2a
100 a = -625
a = -6.25
then
F = m a