How Is Heat Calculated from Friction Over Time?

In summary: that would be dissipated if there was no friction at all. errr... no, unless the volume is changing in which case yes.
  • #1
MrJingles
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How does one calculate the heat generated by a force of friction with respect to time?

Let's stick with constant mass and assume that we know everything but heat.


Thanks for looking in,

MJ
 
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  • #2
All of the energy dissipated by friction can generally being dissipated thermally --> i.e. through heat.
Calculate the work done by friction, and there it is.
 
  • #3
MrJingles said:
How does one calculate the heat generated by a force of friction with respect to time?Let's stick with constant mass and assume that we know everything but heat.

A very simple model: a mass m, moving at constant velocity v, on a level surface, with an applied constant force F and kinetic friction f acting in the opposite direction:

In this case the power of the applied force is F.v (which here is just F*v) and, by conservation of energy, the only energy transfer is to the internal energy of the block/floor. Hence the 'heat generated' with repect to time is just F*v - in Watts.

I think this is correct. Hope this helps. Or is it too simple a model?
 
  • #4
lzkelley said:
All of the energy dissipated by friction can generally being dissipated thermally --> i.e. through heat.
Calculate the work done by friction, and there it is.

If you're pulling an object but the friction of the floor is stronger than you (hence, no movement -> no work), does the object/floor still warm up a little bit?

If it doesn't, where is the energy (which you're consuming in the futile effort of pulling the object) dissipated?
 
  • #5
Domenicaccio said:
If you're pulling an object but the friction of the floor is stronger than you (hence, no movement -> no work), does the object/floor still warm up a little bit?

If it doesn't, where is the energy (which you're consuming in the futile effort of pulling the object) dissipated?
You might well break into a sweat due to your exertion. That should answer your question. :smile:
 
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  • #6
Domenicaccio said:
If you're pulling an object but the friction of the floor is stronger than you (hence, no movement -> no work), does the object/floor still warm up a little bit?

If it doesn't, where is the energy (which you're consuming in the futile effort of pulling the object) dissipated?
Biochemical energy is expended just clenching muscles. A compressed spring, on the other hand, doesn't expend energy to exert a static force. So you could say that your energy efficiency is zero when applying a static force.
 
  • #7
russ_watters said:
Biochemical energy is expended just clenching muscles. A compressed spring, on the other hand, doesn't expend energy to exert a static force. So you could say that your energy efficiency is zero when applying a static force.

So there is no minimal heating of the object/floor in that case?
 
  • #8
Domenicaccio said:
So there is no minimal heating of the object/floor in that case?

Theoretically: No. Practically: Yes. When a force is exerted onto smt anh presses it, it may deforms and that gives off heat.
 
  • #9
Ehh, sort of. It may generate heat while it is being compressed, but once compressed and left in a static state, it will generate no more heat.
 
  • #10
russ_watters said:
Ehh, sort of. It may generate heat while it is being compressed, but once compressed and left in a static state, it will generate no more heat.

Clear, thanks!

It makes sense, otherwise I suppose that any object under some sort of tension/compression (even that of its own weight) would give off heat and therefore slowly lose energy...
 
  • #11
"It makes sense, otherwise I suppose that any object under some sort of tension/compression (even that of its own weight) would give off heat and therefore slowly lose energy..."

errr... no, unless the volume is changing in which case yes. But basically the answer to the OP's question is that the kinetic energy lost due to friction is basically the heat energy
 

What is heat generated by friction?

Heat generated by friction is the heat produced when two surfaces rub against each other, converting mechanical energy into thermal energy. This can be seen when two objects are rubbed together and become warm to the touch.

How is heat generated by friction measured?

Heat generated by friction can be measured through the coefficient of friction, which is a unitless value that represents the amount of friction between two surfaces. It can also be measured in joules or watts, which are units of energy and power, respectively.

What factors affect the amount of heat generated by friction?

The amount of heat generated by friction is affected by several factors, including the speed at which the surfaces are rubbing against each other, the force applied, the materials of the surfaces, and the surface area of contact. Generally, the higher the speed and force, the more heat will be generated.

What are the practical applications of heat generated by friction?

Heat generated by friction has many practical applications, including in brake systems of vehicles, polishing and sanding surfaces, starting fires through frictional heating, and even in cooking. It is also used in industrial processes such as metalworking and welding.

How can heat generated by friction be reduced?

There are several ways to reduce the amount of heat generated by friction, including using lubricants between surfaces, using materials with lower coefficients of friction, and decreasing the speed and force of rubbing. Proper maintenance and regular cleaning of surfaces can also help reduce friction and heat generation.

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