a 2500kg car is travelling at a constant speed of 14 m/s along an icy, but straight and level road. the driver of the car, seeing an approaching traffic light turn red., slams on the brakes. Wheels locked and ttired skidding, the car slide to a halt in a distance of 25m. What is the coefficient of friction

Respuesta :

Answer:

0.40

Explanation:

Given that :

the mass of the caer = 250 kg

initial speed = 14 m/s

final speed = 0 m/s

distance  s = 25 m

Using the equation of motion

[tex]v^2 = u^2 + 2as[/tex]

making a the subject of the formula ; we have:

[tex]v^2-u^2 = 2as[/tex]

[tex]a= \dfrac{v^2-u^2 }{2 \ s}[/tex]

[tex]a= \dfrac{(0)^2-(14)^2 }{2 \ (25)}[/tex]

[tex]a= \dfrac{0-196 }{50}[/tex]

[tex]a= \dfrac{-196 }{50}[/tex]

a = -3.92 m/s²

However; the relation for the coefficient of the kinetic static friction can be expressed as:

[tex]f= \mu_k *mg= ma[/tex]

[tex]f= \mu_k *g= a[/tex]

[tex]f= \mu_k = \dfrac{a}{g}[/tex]

[tex]f= \mu_k = \dfrac{3.92}{9.8}[/tex]

[tex]f= \mu_k = 0.40[/tex]