A car travels at 63 mi/h when the brakes are suddenly applied.
Consider how the tires of a moving car come in contact with the road.
When the car goes into a skid (with wheels locked up), the rubber of the tire is moving with respect to the road; otherwise, when the tires roll, normally the point where the tire contacts the road is stationary. Assume the coefficients of friction between the tires and the road are μK = 0.80 and μS = 0.90

(a) Calculate the distance required to bring the car to a full stop when the car is skidding.

(b) Calculate the distance required to bring the car to a full stop when the wheels are not locked up.


halp

F=m*a
The normal force is m*g

The only force on the car is the force of friction, which is just m*g*μ

so....

m*g*μ = m*a
g*μ = a

using the formula:


V = velocity final = 0
V_0 = velocity initial = 63 mi/h
a = g*μ, (see above)
μ = coefficient of friction (different for each of the 2 problems)
g = uhhh fuck me i don't know g in mile/hour^2, look that shit up
r_0 = inital distance = 0 miles

r = final distance = solve for r since you know everything else, and you'll have your answer(s), in miles.



This post was edited by Azrad on Sep 19 2013 09:33pm

Doesn't americans use SI in physics? :S

normally yes, but once in a while someone hits you with horrible units.