# Coefficient of static friction of a sliding box

• DB91
In summary: If the box were sitting stationary on the incline, and needed no extra external force to keep it steady, what direction would you be drawing the arrow showing the friction force that is acting on the block?The arrow would be pointing down the incline.
DB91

## Homework Statement

A box rest on an incline making a 34 angle with the horizontal. It is found that a parallel force to the incline of at least 235 N can prevent the box from sliding down the incline. If the weight of the box is 800 N, find the coefficient of static friction between the box and the incline.

## Homework Equations

Just wanted to know what formula to use or at least how construct the formula.

## The Attempt at a Solution

Didn't know where to start.

DB91 said:

## Homework Statement

A box rest on an incline making a 34 angle with the horizontal. It is found that a parallel force to the incline of at least 235 N can prevent the box from sliding down the incline. If the weight of the box is 800 N, find the coefficient of static friction between the box and the incline.

## Homework Equations

Just wanted to know what formula to use or at least how construct the formula.
Hi DB91. http://img96.imageshack.us/img96/5725/red5e5etimes5e5e45e5e25.gif

You are not needing a formula yet! The first step is to draw a clear, neat diagram, to mark on everything you know here.

Post that when you've done it.

Last edited by a moderator:
NascentOxygen said:
Hi DB91. http://img96.imageshack.us/img96/5725/red5e5etimes5e5e45e5e25.gif

You are not needing a formula yet! The first step is to draw a clear, neat diagram, to mark on everything you know here.

Post that when you've done it.

Last edited by a moderator:
Would it be: (800×9.8 sin⁡34)/235 = f

DB91 said:
Your image doesn't show up. (I doubt that that is a link to an image, anyway.)

Last edited:
Your image is accessible now. (I think you have included a lot of whitespace in it?)

The question refers to an arrangement of forces needed "to prevent the box from sliding down" the incline. So this tells you the direction in which friction will be acting in your forces diagram. So, in what direction will friction be acting here, and why have you decided it must be in this direction?

NascentOxygen said:
Your image is accessible now. (I think you have included a lot of whitespace in it?)

The question refers to an arrangement of forces needed "to prevent the box from sliding down" the incline. So this tells you the direction in which friction will be acting in your forces diagram. So, in what direction will friction be acting here, and why have you decided it must be in this direction?

The friction force would be acting in the opposite direction of the force applied on the box. Right?

DB91 said:
The friction force would be acting in the opposite direction of the force applied on the box. Right?
Not necessarily. It depends on what the applied force is tending to do.

How could you work out the correct answer to this?

NascentOxygen said:
Not necessarily. It depends on what the applied force is tending to do.

How could you work out the correct answer to this?

(800×9.8 sin⁡34)/235 = f...?

Sorry physics is defiantly not one of my strong points.

Well, if the box were sitting stationary on the incline, and needed no extra external force to keep it steady, what direction would you be drawing the arrow showing the friction force that is acting on the block?

## 1. What is the coefficient of static friction?

The coefficient of static friction is a dimensionless quantity that measures the resistance of two surfaces to slide against each other when there is no relative motion between them.

## 2. How is the coefficient of static friction determined?

The coefficient of static friction can be determined experimentally by measuring the maximum force required to move an object along a surface without causing it to slide. This force is then divided by the weight of the object to obtain the coefficient of static friction.

## 3. What factors affect the coefficient of static friction?

The coefficient of static friction is influenced by various factors such as the nature of the surfaces in contact, the roughness of the surfaces, the amount of force applied, and the presence of any lubricants or contaminants on the surfaces.

## 4. How does the coefficient of static friction affect the motion of a sliding box?

The coefficient of static friction determines the minimum force required to initiate the motion of a sliding box and also affects the acceleration and speed of the box. A higher coefficient of static friction will result in a greater resistance to motion and slower acceleration.

## 5. Can the coefficient of static friction change over time?

Yes, the coefficient of static friction can change over time due to factors such as wear and tear of the surfaces, changes in temperature, or the accumulation of debris or moisture on the surfaces. It is important to regularly check and adjust the coefficient of static friction to ensure safe and efficient movement of objects.

• Introductory Physics Homework Help
Replies
11
Views
2K
• Introductory Physics Homework Help
Replies
6
Views
2K
• Introductory Physics Homework Help
Replies
14
Views
2K
• Introductory Physics Homework Help
Replies
48
Views
6K
• Introductory Physics Homework Help
Replies
24
Views
2K
• Introductory Physics Homework Help
Replies
8
Views
2K
• Introductory Physics Homework Help
Replies
1
Views
1K
• Introductory Physics Homework Help
Replies
11
Views
3K
• Introductory Physics Homework Help
Replies
5
Views
591
• Introductory Physics Homework Help
Replies
1
Views
2K