Chapter 4 Notes | Physics 1st Year

“Work and Energy”

Index:

1. Work done by a constant Force
2. Work done by a variable Force
3. Work done by gravitational
4. Power
5. Energy
6. Work Energy Principle
7. Absolute Potential Energy
8. Escape Velocity
9. Interconversion of Potential Energy and Kinetic Energy
10. Conservation of Energy
11. Non Conventional Energy Sources
12. Energy from Tides
13. Energy from Waves
14. Solar Energy
15. Energy from Biomass
16. Energy from Waste Products
17. Geothermal Energy

See Also: 1st Year Paper Scheme 2021

See Also: 2nd Year Paper Scheme 2021

Key Points:

1. The Work done On a body by a constant force is defined as the product of the magnitude of the displacement and the component of the force in the direction of the displacement.
   W=F.d = Fdcosθ
2. Work done by a variable force is computed by dividing the path into very small displacement intervals then taking the sum of work done for all such intervals
3. Graphically, the work done by a variable force in moving a particle between two points is equal to the area under the F cos θ verses d curves between these two points.
4. When an object is moved in the gravitational field of the each, the work is done by the gravitational force. The work done in the Earth’s gravitational field is independent of the path followed, and the work done along a closed path is zero. such a force field is called conversation field.
5. Energy of a body is its capacity to do work. The Kinetic energy possessed by a body due to its motion.
6. The potential energy is possessed by a body because of its position in a force field.
7. The absolute P.E Of a body on the surface of Earth is
   Ug=-GMm/R
8. The initial velocity of a body with which it should be projected upward so that it does not come back, is called escape velocity.
9. Some of the non conventional energy sources are
   1. Energy from the tides
   2. Energy from waves
   3. Solar energy
   4. Energy from biomass
   5. Energy from waste products
   6. Geothermal energy