Work, Energy and Power : A Comprehensive Guide For All Exams.

 Work, Energy and Power are fundamental concepts in physics that explain how forces cause motion, how energy is transferred and how quickly work is done. These principles are essential in understanding mechanics, engineering, and various real-world applications, from simple machines to advanced technologies.

What is Work ?

Work is done when a force is applied to an object, and the object moves in the direction of the applied force. If there is no movement, no work is done.

Formula of Work

W = F . d . cos θ 

• W = Work (Joules, J)

• F = Force applied (Newtons, N)

• d = Displacement (meters, m)

• θ = Angle between force and displacement

Types of Work

1. Positive Work : When the force and displacement are in the same direction.

Example : Lifting an object.

2. Negative Work : When the force and displacement are in opposite directions.

Example : friction slowing a moving object.

3. Zero Work : When there is no displacement or the force is perpendicular to the displacement.

Example : Carrying an object Horizontally.

What is Energy ?

Energy is the ability of an object to perform work. It exists in various forms and can be transformed from one form to another.

Types of Energy

1. Kinetic Energy : The energy of motion.

K E = ½mv²

2. Potential Energy : The stored energy due to position.

P E = mgh

3. Mechanical Energy : The sum of kinetic and Potential energy.

ME = KE + PE

Other forms of Energy :

• Thermal Energy

• Chemical Energy

• Electrical Energy

• Nuclear Energy

Laws of Conservation of Energy 

Energy cannot be created or destroyed. It can only be transformed from one form to another.

Total Energy Before = Total Energy After

What is Power ?

Power is the rate at which work is done or energy is transferred.

Formula of Power

P = W / T

• P = Power (Watts, W)

• W = Work done (Joules, J)

• T = Time Taken (seconds, s)

Units of Power 

• Watt (W) : 1 W = 1 J/s

• Kilowatt (kW) = 1 kW = 1000 W

• Horsepower (hp) = 1 hp = 746 W

Practical Applications of Work, Energy and Power

1. Transportation : Vehicles use fuel to generate Mechanical Energy.

2. Electricity Generation : Hydroelectric plants convert gravitational potential energy into electrical energy.

3. Sports : Athletes use kinetic and potential energy in activities like running and jumping.

4. Machines : Engines and motors work by converting energy into useful mechanical work.

Read About : Force and Newton's Laws of Motion.