Coefficient of static friction

In summary, the conversation is discussing the minimum force required to move a block of mass m resting on a horizontal surface with a coefficient of static friction μs. The options for the minimum force and angle needed are presented, and the equations for static friction and normal force are mentioned.
  • #1
sonutulsiani
138
0

Homework Statement



A block of mass m is resting on a horizontal surface whose coefficient of static friction is μs.

http://bcs.whfreeman.com/WebPub/Physics/tiplerphysics6e_bridge/question_bank_images/fig5-65.png?2439

Which of the following statements (if any) are true?

A. If you want to apply the minimum possible force to move the block, you should apply it with the force pulling upward at an angle θmin = arctan μs.
B. The minimum force necessary to start the block moving is μs mg/ √1 + μs2.
C. Once the block starts moving, if you want to apply the least possible force to keep it moving, you should keep the angle at which you are pulling the same.

There may be more than 1 answer

Homework Equations



Fs=μs Fn

The Attempt at a Solution



No idea.
 
Physics news on Phys.org
  • #2
Hi sonutulsiani! :smile:

Call the normal force N, and the friction force H.

Then do a vector triangle or x and y component equations for a fixed angle θ …

what do you get? :smile:
 
  • #3


I can provide an explanation and clarification of the concept of coefficient of static friction and how it relates to the given statements.

Coefficient of static friction (μs) is a measure of the amount of friction between two surfaces in contact when there is no relative motion between them. It is a dimensionless quantity and its value depends on the nature of the surfaces in contact.

Statement A is not entirely accurate. The minimum force required to move the block is not dependent on the angle at which the force is applied, but rather on the coefficient of static friction and the normal force (Fn) acting on the block. The correct equation for the minimum force required to move the block is Fmin = μs Fn.

Statement B is also not entirely accurate. The correct equation for the minimum force required to start the block moving is Fmin = μs mg, where m is the mass of the block and g is the acceleration due to gravity.

Statement C is correct. Once the block starts moving, the force required to keep it moving is less than the minimum force required to start it moving. This force (F) is given by the equation F = μk Fn, where μk is the coefficient of kinetic friction, which is usually lower than the coefficient of static friction. The angle at which the force is applied does not affect the force required to keep the block moving.

In conclusion, the correct statements are: B and C.
 

What is the coefficient of static friction?

The coefficient of static friction is a measurement of the amount of force required to move an object from a state of rest, or static, to a state of motion without any acceleration. It is a dimensionless quantity, meaning it has no units, and is denoted by the symbol μ (mu).

How is the coefficient of static friction calculated?

The coefficient of static friction is calculated by dividing the maximum amount of force needed to move an object by the normal force acting on the object. This can be represented by the equation μ = F/N, where μ is the coefficient of static friction, F is the maximum force needed to move the object, and N is the normal force.

What factors affect the coefficient of static friction?

The coefficient of static friction is affected by the types of materials in contact, the roughness of the surfaces, and the normal force. Other factors such as temperature and humidity can also have an impact on the coefficient of static friction.

Why is the coefficient of static friction important?

The coefficient of static friction is important because it helps determine the stability and safety of objects on surfaces. It is also a crucial factor in understanding the motion and movement of objects, especially in engineering and physics applications.

What is the difference between static and kinetic friction?

Static friction occurs when an object is at rest and is being acted upon by an external force. Kinetic friction, on the other hand, occurs when an object is in motion and is experiencing resistance from the surface it is moving on. The coefficient of kinetic friction is typically lower than the coefficient of static friction.

Similar threads

  • Introductory Physics Homework Help
Replies
11
Views
1K
  • Introductory Physics Homework Help
Replies
16
Views
1K
  • Introductory Physics Homework Help
Replies
4
Views
2K
  • Introductory Physics Homework Help
Replies
1
Views
3K
  • Introductory Physics Homework Help
Replies
6
Views
1K
  • Introductory Physics Homework Help
Replies
7
Views
264
  • Introductory Physics Homework Help
Replies
13
Views
1K
  • Introductory Physics Homework Help
Replies
2
Views
2K
  • Introductory Physics Homework Help
Replies
11
Views
452
  • Introductory Physics Homework Help
2
Replies
36
Views
2K
Back
Top