Does static friction always act on objects at rest?

  • Context: High School 
  • Thread starter Thread starter Nstraw
  • Start date Start date
  • Tags Tags
    Body Friction Rest
Click For Summary

Discussion Overview

The discussion revolves around whether static friction acts on objects at rest, specifically considering scenarios where no external forces are applied, such as a person standing still or a book on a table. The scope includes conceptual understanding of friction types and their implications in different situations.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants propose that static friction does not act on a body at rest unless there are external forces applied, such as a person standing still.
  • Others argue that static friction can act on a body when it is attempting to move, as in the case of a person trying to walk, where one foot exerts a backward force while the other remains stationary due to static friction.
  • A later reply mentions that a book on a horizontal table experiences zero static friction when at rest, but static friction will increase when an external force is applied to prevent slipping.
  • There is a distinction made between static friction and sliding friction, with the latter taking over once an object begins to move.

Areas of Agreement / Disagreement

Participants express differing views on whether static friction acts on objects at rest, with some asserting it does not while others provide examples where it does come into play when movement is attempted. The discussion remains unresolved regarding the conditions under which static friction is considered to act.

Contextual Notes

Limitations include the lack of consensus on definitions of static friction in various contexts and the dependence on specific scenarios, such as the surface conditions and external forces applied.

Nstraw
Messages
27
Reaction score
0
Will the friction act on a body at rest. Do not take in the case of inclined plane.
 
Physics news on Phys.org
It depends. What situation do you have in mind? Is the body being pushed?
 
Well just consider a man standing.
 
In that case, no there is no friction acting on the man. There is, however, a distinction between "static friction" and "sliding friction". If the man attempts to move forward, he moves one foot forward which causes his other foot to exert a force backward. That foot does not move backward because of the static friction which acts on it even though that foot is not moving. If the static friction is not enough, if he is on a slippery floor, the force backward will be greater than the static friction and that foot will slide backward (now subject to sliding friction which is less than the static friction) making it difficult to walk forward.
 
If the man was standing on a slippery floor than he will be just moved by throwing some object in direction opposite To him but he can't do it on less slippery surface than isn't friction is preventing him To move
 
Nstraw said:
Well just consider a man standing.
As Halls' says, there's no friction acting in this case.

Another example would be a book on a horizontal table. If it's just sitting there, the static friction is zero. But start pushing it and the static friction will increase to prevent slipping--up to the point of maximum static friction. (Once you get it moving, kinetic friction takes over.)
 

Similar threads

High School Static friction needed for rolling without slipping
  • · Replies 4 ·
Replies
4
Views
2K
High School Friction forces on the tires of a moving car
  • · Replies 7 ·
Replies
7
Views
2K
High School Friction and Newton's laws in car braking systems
  • · Replies 10 ·
Replies
10
Views
2K
Undergrad What determines the direction of static friction forces?
  • · Replies 6 ·
Replies
6
Views
2K
High School Why doesn't static friction move the other object?
  • · Replies 9 ·
Replies
9
Views
2K
High School Are frictional forces action forces or reaction forces?
  • · Replies 14 ·
Replies
14
Views
2K
High School Why do objects break? (in the case of a body at rest on a surface)
  • · Replies 2 ·
Replies
2
Views
2K
High School Why is static friction necessary for pure rolling?
  • · Replies 4 ·
Replies
4
Views
3K
High School The power output of a vehicle when descending hills
  • · Replies 29 ·
Replies
29
Views
2K
High School Equivalence of Frictional and Applied Force
  • · Replies 2 ·
Replies
2
Views
2K