Verified answer

Solution :

Given :

u = coefficient of friction = 0.80

m = mass = 1,000 kgs

vi = initial velocity = 20m/s

vf = final velocity = 0

a = acceleration = ?

s = distance/skid marks = ?

F = uN

F = (0.80) x (1,000 kg x 9.81N/kg)

F = 7,848.00 Newtons

But :

F = ma

a = F/m

a = (7,848.00N)/(1,000)

a = 7.848 m/sec^2 (deceleration) - to be negative acceleration

vf^2 = vi^2 + 2as

0 = 20^2 - (2 x 7.848) x s

15.696s = 400

s = 400/15.696

s = 25.48 meters (Answer) - The length of skid marks.

Hope this helps.

Lul skid marks.