Question

Under normal conditions, the car rolls to a stop, leaving no skid along the road surface. However, when the driver brakes suddenly, the tires can lock, causing the car to skid. Police officers use the length of skid marks d to estimate the initial speed v0 of the vehicle at the onset of braking. Determine the coefficient of kinetic friction. Express your answer in terms of d and v0 and free fall acceleration g.

Answer 1

`\mu = (v_0^2)/(2gd)`

Step-by-step explanation:

given,

initial velocity = v₀

final velocity = 0

length of skid = d

acceleration due to gravity

using equation of motion

v² - u² = 2 a s

0 - v₀² = 2 a d

`a = (-v_0^2)/(2d)`

using expression for acceleration due to skidding

`(-v_0^2)/(2d)= -\mu g`

`\mu = (v_0^2)/(2gd)`