Question

Can anyone explain what is positive, negative and zero work?

Please it's urgent..

Answer 1

Heya,
Here is your answer...
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•Positive and negative work done:-

Work can be either positive or negative: if the force has a component in the same direction as the displacement of the object, the force is doing positive work. If the force has a component in the direction opposite to the displacement, the force does negative work.

If you pick a book off the floor and put it on a table, for example, you're doing positive work on the book, because you supplied an upward force and the book went up. If you pick the book up and place it gently back on the floor again, though, you're doing negative work, because the book is going down but you're exerting an upward force, acting against gravity. If you move the book at constant speed horizontally, you don't do any work on it, despite the fact that you have to exert an upward force to counter-act gravity.

•Zero work done:-

Work is done only when a certain force is applied on a object and the object moves a certain distance on the direction of the applied force. hence work done is zero when the direction is perpendicular.

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Answer 2

Positive work : when force and displacement both are in the same direction the work done is said to be positive
Negative work : when force and displacement are in opposite directions the work done is said to be negative
Zero work :when force and displacement are perpendicular to each other the work done is said to be zero