Below is a concise list of key definitions from Chapter 4: Work and Energy

Below is a concise list of key definitions from Chapter 4: Work and Energy of the 11th Class Physics syllabus for the Federal Board of Intermediate and Secondary Education (FBISE), aligned with the National Book Foundation (NBF) curriculum. These definitions cover the essential concepts related to work, energy, and power as typically presented in this chapter.

1. Work: A scalar quantity defined as the product of the force applied on an object and the displacement in the direction of the force, given by W = F·s = Fs cosθ.
2. Joule: The SI unit of work and energy, equivalent to the work done when a force of 1 newton displaces an object by 1 meter in the direction of the force (1 J = 1 N·m).
3. Energy: The capacity of a body to do work, measured in joules.
4. Kinetic Energy (KE): The energy possessed by an object due to its motion, given by KE = ½ mv², where m is mass and v is velocity.
5. Potential Energy (PE): The energy possessed by an object due to its position or configuration, often gravitational potential energy, given by PE = mgh, where m is mass, g is gravitational acceleration, and h is height.
6. Gravitational Potential Energy: The potential energy of an object due to its position in a gravitational field, calculated as PE = mgh.
7. Law of Conservation of Energy: Energy cannot be created or destroyed, only transformed from one form to another; the total energy of an isolated system remains constant.
8. Mechanical Energy: The sum of kinetic energy and potential energy in a system, given by ME = KE + PE.
9. Work-Energy Theorem: The net work done on an object is equal to the change in its kinetic energy, expressed as W_net = ΔKE.
10. Power: The rate at which work is done or energy is transferred, given by P = W/t, where W is work and t is time.
11. Watt: The SI unit of power, equivalent to 1 joule of work done per second (1 W = 1 J/s).
12. Efficiency: The ratio of useful output energy or work to the total input energy or work, expressed as a percentage, Efficiency = (Output/Input) × 100.
13. Conservative Force: A force where the work done is independent of the path taken and depends only on the initial and final positions (e.g., gravity, spring force).
14. Non-Conservative Force: A force where the work done depends on the path taken, often converting mechanical energy into other forms like heat (e.g., friction, air resistance).
15. Elastic Potential Energy: The potential energy stored in a deformed elastic object (e.g., a stretched spring), given by PE = ½ kx², where k is the spring constant and x is the displacement.
16. Escape Velocity: The minimum velocity required for an object to escape the gravitational pull of a celestial body, given by v_e = √(2GM/r), where G is the gravitational constant, M is the mass of the body, and r is the radius.
17. Absolute Gravitational Potential Energy: The potential energy of an object at a point in a gravitational field, given by PE = -GMm/r, where G is the gravitational constant, M and m are masses, and r is the distance between their centers.

These definitions encapsulate the core concepts of work, energy, and power from Chapter 4 of the FBISE 11th Class Physics curriculum. If you need further explanation or additional terms, please let me know!