How to remove confusion for sign in work done ..sometimes it comes + and sometime negative?

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Jayanta Sinha

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It all has to do with the basic definition of work, W = F·?x? Work is positive if F and ?x are in the same direction, and negative if they are in opposite directions. Imagine you are pushing on a piston containing a gas. You are exerting a force on it (the "system"), and it is exerting an equal-but-opposite...
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It all has to do with the basic definition of work, W = F·?x? Work is positive if F and ?x are in the same direction, and negative if they are in opposite directions. Imagine you are pushing on a piston containing a gas. You are exerting a force on it (the "system"), and it is exerting an equal-but-opposite force back on you (the "surroundings") If the gas is allowed to expand as you push on it, the force on the system (i.e. the gas) is opposite to the displacement, and so there is negative work done on the system. Also, the force on the surroundings (i.e. you) is in the same direction as displacement, so positive work is done on the surroundings. In other words, the system does work on the surroundings, or positive work is done by the system rather than on the system. If a gas compresses, things are the other way around. In thermodynamics, one adopts a definition of "work" and specifies whether it is positive for work done by the system or on the system. As far as I'm aware, it's common to say work done by the system is positive, or in other words: dW = P dV? Hope that helps. read less
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If the force displaces the object in the same direction as the force is applied then work done is positive. If the displacement of object is in opposite direction to that of force then work done is negative.
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Teaching is my passion!!!!

W = F .S COS(theta) ...so if theta is 0 to 90 OR 0 TO -90...W IS POSITIVE ..ELSE NEGATIVE...(IF (theta) is exactly 90 or 270...W IS 0
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Physics Tutor

Work = Force x displacement, when the force applied on object and displacement of object is in same direction, work done is positive and when force applied on object and displacement of object are in opposite direction work done is negative.
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Physics teacher

SIGN is depending upon direction
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Work done on the system is positive and work done by the system is negative.
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Tutor

Work done by the system is positive and work done to the system is negative. Again work done is a thermodynamic quantity. Also in layman's language the work done in the direction of applied force is positive and work done against the direction of applied force is negative.
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Headstart to assured 95+ score in math

Rishi sir is correct :)
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Teaching is my passion!!!!

Work done by the system is positive and work done to the system is negative. Again work done is a thermodynamic quantity. Also in layman's language the work done in the direction of applied force is positive and work done against the direction of applied force is negative,
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"Read , Recall and Procure"

Work done by the system is positive and work done to the system is negative. Again work done is a thermodynamic quantity. Also in layman's language the work done in the direction of applied force is positive and work done against the direction of applied force is negative
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