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Josielle Abdilla
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When we say the work done against friction, what do we mean by that? This concept is really worrying me.Thanks in advance!
Josielle Abdilla said:When we say the work done against friction, what do we mean by that? This concept is really worrying me.Thanks in advance!
Friction (like Electrical Resistance) is never a source of Energy; it describes an energy loss mechanism. So we say you have to work 'against it'. The work done is the Friction Force times the Distance that the surfaces move (slip) relative to each other.Josielle Abdilla said:When we say the work done against friction, what do we mean by that? This concept is really worrying me.Thanks in advance!
I would say that the expression is from the Eighteenth Century. It gives the impression that things have to be 'got going' before they accelerate because of their mass. F=Ma applies for all velocities, however low, as long as friction or other static forces, like a rope restraint are not involved. The statement is, presumably mistakenly related to the sometimes very small effect of static friction just before things get moving and can easily be due to their Mass. i.e. high mass has high weight so a high static friction force will be 'related to' Mass but it's not related to Inertia. In fact, I do not like the term Inertia - certainly not in Newtonian Mechanics. Mass and Momentum seem to be adequate (and defined) terms to describe those rather arm-waving effects that are sometimes put down to the effect of Inertia. Afaiac, inertia is what prevents us from getting down to work and is not a good physical reason for a restriction of movement.Josielle Abdilla said:Thanks a lot. Besides that, what does it mean when an object overcomes the inertial mass, in order to accelerate?
Where does the term "overcome" come into it? Newton's First and Second Laws of Motion state the situation very adequately. A Force is necessary to produce acceleration - and the net force needed to produce a given acceleration is proportional to the Mass (even as the Mass or Velocity approach zero). The distinction between Inertial and Gravitational Mass is how they relate to Non Gravitational and Gravitation forces. In our system of units, the two masses measure the same.Josielle Abdilla said:Thanks a lot but do you have to overcome the inertial mass to accelerate? Or to move at constant velocity?
But do you take my point about "overcome"? I would say that a totally linear relationship does not imply any threshold / overcoming value. The result is just proportional and exactly what you would expect, for a given number of kilograms, whether those kg were measured with a set of lab scales or in a rocket with a known acceleration. The 'difference' between the two masses is a very esoteric one and you'd need to have been introduced to GR at a reasonable level before it would be relevant. I'd bet that Newton would have had a useful conversation about it of course (smart cookie that he was) but he wouldn't have acknowledged any 'threshold' effect of a force.Josielle Abdilla said:I have only just started physics at advanced a few month's ago and pir physics teacher mentioned about inertial mass
Work done against friction is the amount of energy that is expended in overcoming the force of friction between two surfaces in contact. It is a measure of the effort required to move an object against the resistance of friction.
The work done against friction can be calculated by multiplying the force of friction by the distance that the object moves against the frictional force. This can be represented by the equation W = Fd, where W is the work done, F is the force of friction, and d is the distance moved.
The amount of work done against friction is affected by several factors, including the force of friction, the type of surfaces in contact, and the distance over which the object moves against the frictional force. Additionally, the coefficient of friction, which is a measure of the roughness of the surfaces, can also impact the amount of work done.
Work done against friction is important because it represents the energy that is lost due to frictional forces. This energy is converted into heat, which can have negative effects on machinery and can also cause wear and tear on surfaces in contact. It is also important to consider when designing machines and systems to ensure that enough energy is available to overcome frictional forces.
The amount of work done against friction can be reduced by using lubricants, which can reduce the coefficient of friction between surfaces. Additionally, using smoother surfaces or reducing the weight of objects can also decrease the amount of work done against friction. Proper maintenance and regular cleaning of surfaces can also help reduce friction and the work done against it.