The simplest \"closed path\" I can think of is raising an object of mass m to a

Question

The simplest "closed path" I can think of is raising an object of mass m to a height h, then lowering the object back to its original position.

Select the true statement about the work done by gravity over this closed path.

1) The work done by gravity while raising the object is (mgh), and the work while lowering it is (-mgh).

2) The work done during both the raising and lowering parts of the path is equal to (-mgh).

3) The work done during both the raising and lowering parts of the path is equal to (mgh).

4) The work done by gravity while raising the object is (-mgh), and the work while lowering it is (mgh).

Explanation / Answer

Option 4 is correct.

Becuase when raising up gravatational force is downward and displacment is upward,therefore angle is 180 degree and cos 180 equal to -1.. therefore work by gravity is - mgh.

When raising down. both gravatational force and displacment downward,both are in same direction ,therefore ange is 0 degree,and cos0 is 1.therefore work is mgh.

NOTE:- work=F S Cos theta.

Where theta is angle between force and distance .

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