Friction increase decrease Help

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Homework Help Overview

The discussion revolves around the effects of changing the angle θ between the horizontal and the applied force on a stationary box, specifically in relation to frictional forces. Participants are examining how this angle affects various forces acting on the box, including the applied force, static friction, normal force, and maximum static friction.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants are attempting to understand the relationship between the angle of applied force and the resulting frictional forces. Questions arise regarding the counterintuitive nature of how increasing the angle affects static friction, with some expressing confusion about why a higher angle would lead to lower friction.

Discussion Status

There is an ongoing exploration of the implications of increasing the angle on the forces involved. Some participants are seeking clarification on the reasoning behind the changes in frictional force, while others are providing insights into the relationship between normal force and friction.

Contextual Notes

Participants are grappling with the concept that increasing the angle does not necessarily correlate with an increase in the normal force, which in turn affects the frictional force. There is a focus on understanding the dynamics of the situation without reaching a definitive conclusion.

jonochui
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Homework Statement



In Fig. 6-12, if the box is stationary and the angle θ between the horizontal and force is increased somewhat, do the following quantities increase, decrease, or remain the same?

http://i.imgur.com/YcOFS.jpg

a) Fx
b) fs
c) FN
d) fs, max
e) If, instead, the box is sliding and θ is increased, does the magnitude of the frictional force on the box increase, decrease, or remain the same?

The Attempt at a Solution



This is correct. But why for a, b, d. Please be help.
a) decrease
b) decrease
c) increase
d) increase
e) increase
 
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I am resurrecting this old post because I am on the same problem. I understand all of these answers except for b. I do not understand and it seems counter intuitive to me to think that the higher my angle of force is on a box the lower the friction force becomes. Wouldn't that mean that i would have an easier time moving something by pushing on it from above than I would from the side?
 
vysero said:
I am resurrecting this old post because I am on the same problem. I understand all of these answers except for b. I do not understand and it seems counter intuitive to me to think that the higher my angle of force is on a box the lower the friction force becomes. Wouldn't that mean that i would have an easier time moving something by pushing on it from above than I would from the side?

Yes, but you are not going much further since Fx is reduced. If you are lifting from above, you are not moving to where you are intended to go.
 
So the force decreases and that's why the friction force decreases?
 
vysero said:
So the force decreases and that's why the friction force decreases?

Yes, friction depends on Pressing force or Normal force. Less pressing force means less friction.
 
See that's why this makes no sense to me. Because we are increasing that angle which means I am pressing on it with more and more weight... I thought this made sense but now its clear to me that I don't know why that would decrease. Because its not saying I am lifting the box it says I am esentually going from pushing on the corner to standing on top of the box.
 
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