Coeffiecent of Kinetic Friction Problem

Click For Summary

Homework Help Overview

The problem involves a car coming to a stop on a horizontal road and seeks to determine the coefficient of kinetic friction between the tires and the road. The context includes the car's initial speed, the time taken to stop, and the relationship between friction and normal force.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants discuss the relationship between stopping time, velocity, and acceleration. Questions arise regarding the derivation of relevant equations, such as how to apply Newton's second law and the necessity of knowing the car's mass.

Discussion Status

The discussion is ongoing, with some participants providing guidance on applying Newton's second law and the role of friction in deceleration. There is acknowledgment of confusion regarding the next steps after calculating acceleration, indicating a productive exploration of the problem.

Contextual Notes

Participants express uncertainty about the need for the car's mass and how to determine the friction force, highlighting potential gaps in information necessary for solving the problem.

c.melissas
Messages
4
Reaction score
0
1. A car is traveling at 15 meters/second on a horizontal road. The brakes are applied and the car sids to a stop in 4 seconds. The coefficient of kinetic friction between the tires and the road is



2. Coefficient of kinetic friction = friction / Normal Force



3. Time to stop / Velocity = 4/15 = .2666. The correct answer is roughly .38, but I have no idea on how to arrive at that.
 
Physics news on Phys.org
c.melissas said:
1. A car is traveling at 15 meters/second on a horizontal road. The brakes are applied and the car sids to a stop in 4 seconds. The coefficient of kinetic friction between the tires and the road is



2. Coefficient of kinetic friction = friction / Normal Force



3. Time to stop / Velocity = 4/15 = .2666. The correct answer is roughly .38, but I have no idea on how to arrive at that.
Where does this equation come from? v = at. Solve for a, then apply Newton's 2nd law to the car.
 
Thanks for the help. I really had no idea how to answer this problem. I am confused on what do after solving for acceleration because I could not find a way to determine the force or the mass of the car.
 
You may not need to know the mass, write out Newton's 2nd for the car. The force acting on the car is the friction force, which is slowing it down (decelerating it) to a stop.
And by the way,welcome to PF!
 
Last edited:
Thank you, and I was able to figure it out.
 

Similar threads

Coefficient of kinetic friction of a block sliding across the ceiling
  • · Replies 7 ·
Replies
7
Views
2K
Coefficient of Friction question for a cart going down a wooden ramp
  • · Replies 18 ·
Replies
18
Views
3K
Does coefficient of kinetic friction depend on speed?
  • · Replies 16 ·
Replies
16
Views
6K
Truck carrying a box, friction problem
  • · Replies 10 ·
Replies
10
Views
6K
Kinetic energy & Conservation of energy
  • · Replies 17 ·
Replies
17
Views
2K
How Is Heat Generated from Friction in Physics Problems?
  • · Replies 6 ·
Replies
6
Views
2K
Stopping distances on a downward slope
  • · Replies 3 ·
Replies
3
Views
2K
Relation between Friction, Velocity, and Acceleration
  • · Replies 16 ·
Replies
16
Views
2K
A ball climbing a ramp while "rolling the wrong way"
  • · Replies 32 ·
2
Replies
32
Views
4K
Kinetic Energy and Newton Forces - distance/speed
  • · Replies 3 ·
Replies
3
Views
2K