Static and Kinetic Frictional Forces

In summary, the conversation discusses a 6.00 kg box sliding across a horizontal floor with a coefficient of kinetic friction of 0.360. The kinetic frictional force acting on the box is determined for three scenarios: when the elevator is stationary, accelerating upward with an acceleration of 1.20 m/s2, and accelerating downward with an acceleration of 1.20 m/s2. The normal force and weight of the box are also discussed, along with the net force on the box in each scenario. The confusion about the weight of the box and the role of the coefficient of kinetic friction is also brought up.
  • #1
princess7115
10
0
A 6.00 kg box is sliding across the horizontal floor of an elevator. The coefficient of kinetic friction between the box and the floor is 0.360. Determine the kinetic frictional force that acts on the box when the elevator is (a) stationary, (b) accelerating upward with an acceleration whose magnitude is 1.20 m/s2, and (c) accelerating downward with an acceleration whose magnitude is 1.20 m/s2.
 
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  • #2
Why did you title this "Static and Kinetic Friction Forces" when there are no static friction forces involved?

The "coefficient of kinetic friction force" is defined as "actual friction force divided by normal force".

On a flat floor, the "normal force" is just the net vertical force.

What is the weight of a 6.00 kg box (the downward force due to gravity)?

If the acceleration is 1.2 m/s2 upward, what additional downward for is there? (F= ma)? What is the net force on the box?

If the acceleration is 1.2m/s2 downward, what is the "upward" force? What is the net force on the box?
 
  • #3
Still Confused

I'm super confused. I got lost after you said find weight. Isn't weight mg? So that would be 6*9.8=58.8N, but I don't know where to go from there. Where does the .360 come in?
 

1. What is the difference between static and kinetic frictional forces?

Static frictional force is the force that prevents an object from moving when a force is applied, while kinetic frictional force is the force that opposes the motion of an object already in motion.

2. How are static and kinetic frictional forces calculated?

Static frictional force can be calculated using the formula Fs = μs * N, where μs is the coefficient of static friction and N is the normal force. Kinetic frictional force can be calculated using the formula Fk = μk * N, where μk is the coefficient of kinetic friction and N is the normal force.

3. What factors affect the magnitude of static and kinetic frictional forces?

The magnitude of both static and kinetic frictional forces depends on the coefficient of friction between the surfaces in contact, the normal force, and the roughness of the surfaces.

4. Can the coefficient of friction change for a given set of surfaces?

Yes, the coefficient of friction can change for a given set of surfaces depending on factors such as temperature, humidity, and the presence of lubricants.

5. What is the role of frictional forces in everyday life?

Frictional forces play a crucial role in everyday life by allowing us to walk, drive, and hold objects without slipping. They also help to stop moving objects and increase traction between surfaces.

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