Finding length of skid marks using f k

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To find the length of skid marks for a car skidding to a halt, the frictional force (fk) is calculated using the coefficient of kinetic friction (µk) and the normal force. For a 1000 kg car traveling at 40 m/s on wet concrete with µk = 0.60, the normal force is 9800 N, resulting in a frictional force of 5880 N. To determine the distance of the skid marks, the acceleration can be found using Newton's second law (F = ma), where the frictional force equals the mass times acceleration. Once the acceleration is known, standard equations of motion can be applied to find the skid distance. This approach effectively combines frictional force and kinematics to solve the problem.
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Finding length of skid marks using fk

Homework Statement



A 1000kg car traveling at a speed of 40m/s skids to a halt on wet concrete where µk = 0.60. How long are the skid marks?

(i know this an easy problem, but i am stuck when trying to find the length of the skid marks.)

Homework Equations



Fg = mg = weight = normal force

fk = µkFN

The Attempt at a Solution



Fg = 1000(9.8) = 9800 N, therefore the normal force = 9800N
µk = .60

fk = .60(9800)
fk = 5800 N

v0 = 40m/s
fk = 5880 N

Where do i go from here to find the distance of the skid marks?

i was thinking maybe using the formula, x = x0 + vt, but i am not sure
 
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Welcome to PF!

Hi physjeff12! Welcome to PF! :wink:
physjeff12 said:
fk = 5880 N

Where do i go from here to find the distance of the skid marks?

i was thinking maybe using the formula, x = x0 + vt, but i am not sure

From fk, find the acceleration, and then use one of the standard constant acceleration equations. :smile:
 


tiny-tim said:
Hi physjeff12! Welcome to PF! :wink:From fk, find the acceleration, and then use one of the standard constant acceleration equations. :smile:

thanks :smile:

and how do i find the acceleration using fk? i don't know any formulas that connect acceleration with friction force.

EDIT: nvm, i am stupid. i found out how. F = ma :smile:
 
Friction is like any other force …

just use good ol' Newton's second law. :wink:​
 

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