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# FSC 1st Year Physics Chapter 4 Notes PDF

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In this post, I am sharing FSC 1st Year Physics Chapter 4 Notes PDF for the students of Intermediate Part 1. This chapter’s name is Work and Energy. Students can download 11th class chapter 4 Work and Energy Notes PDF in there laptop or mobile. These Physics Notes are for all the boards working under Punjab Board like Gujranwala Board, Lahore Board, Faisalabad Board, Multan Board, Rawalpindi Board, Sargodha Board, DG Kahn Board, and Sahiwal Board. Here are the complete FSC 1st Year Physics Notes PDF chapterwise.

## Fsc Part 1 Physics Chapter 4 Work and Energy Notes PDF Download

### What is work?

When force acts on a body and causes a displacement in the body work said to be done.
OR
The product of the magnitudes of the displacement and the component of force in the direction of displacement called work
W = F.d
W = Fd cos

### Define gravitational field. Prove that work done in the earth’s gravitational field independent of the path followed.

The space around the earth in which its gravitational force acts on a body called gravitational field.
Work Done In Gravitational Field
when an object moved in the gravitational field, the work done by gravitational force. If the displacement is in the direction of gravitational force, the workk is positive. However, if the direction of displacement is opposite to that of the direction of the gravitational force, then the work is negative. If displacement is perpendicular to force, work done is zero.
Consider an object of mass m being displaced with constant velocity from point A to B along different paths in the presence of the gravitational force as shown in figure. In this case the gravitational force is equal to the weight mg of the object.

### Work done along the path ADB:

let the object moved through path 1. Work done by the gravitational force along the path ADB split into two parts.

### Work done along path AD:

the work done along the path AD is zero because the weight mg is perpendicular to this path

### Work done along the path DB:

the work done along the path DB is mgh because the direction of the weight mg is opposite to that of the direction of the displacement h of this path
WDB = mgh
Hence total work done in moving the object from A to B along path 1 is