1500kg motor car was travelling at 36m\s comes to rest over a distance of 40m.calculate. {a}retardation. {b}an average force that brings the car to rest

Answer 1

v = Vi + a t
0 = 36 + a t
t = -36/a

d = Vi t + .5 a t^2

40 = 36 (-36/a) + .5 (a)(36^2/a^2)

40 = - 36^2/a + .5 *36^2/a

80 a = -36^2

a = -16.2 m/s^2

then F = m a
= -1500(16.2) Newtons