HP TGT Physics: Work, Energy & Power Notes with MCQs

HP TGT Physics — Chapter 3: Work, Energy & Power

Key Points with Explanation

Ø  Work

Work is done when a force moves an object in the direction of force.
Formula: Work (W) = Force (F) × Displacement (s) × cosθ
👉 If force and displacement are in same direction, θ = 0°, so cosθ = 1.
Unit: Joule (J)

Example: Pushing a box along the floor.

Ø  Positive, Negative & Zero Work

• Positive Work: Force and displacement in same direction.
  E.g. Lifting a bucket upwards.
• Negative Work: Force and displacement in opposite directions.
  E.g. Friction acting on moving object.
• Zero Work: If displacement is zero or force is perpendicular to motion.
  E.g. Carrying a bag horizontally.

Ø  Energy

Energy is the capacity to do work.
Unit: Joule (same as work).

Forms of Energy:

• Kinetic Energy
• Potential Energy
• Chemical Energy
• Heat Energy etc.

Ø  Kinetic Energy (KE)

Energy due to motion.
Formula: KE = ½ mv²
m = mass, v = velocity.

Example: Moving car has kinetic energy.

Ø  Potential Energy (PE)

Energy stored due to position or shape.
Formula: PE = mgh
m = mass, g = gravity, h = height.

Example: Water stored in a dam.

Ø  Law of Conservation of Energy

Energy cannot be created or destroyed, only transformed from one form to another.
Example: When you drop a ball, potential energy converts to kinetic energy.

Ø  Power

Power is the rate at which work is done or energy is transferred.
Formula: Power (P) = Work done (W) / Time (t)
Unit: Watt (W)

Example: A machine doing 100 Joules of work in 2 seconds has 50 Watts power.

✅ Important Formulas

Concept	Formula
Work	W = F × s × cosθ
Kinetic Energy	KE = ½ mv²
Potential Energy	PE = mgh
Power	P = W/t

Ø  MCQs for Work, Energy & Power

What is the unit of work?
A) Newton
B) Joule
C) Watt
D) Pascal

Which one is an example of negative work?
A) Pushing a box
B) Friction opposing motion
C) Lifting an object
D) Heating water

Which formula shows Kinetic Energy?
A) mgh
B) F × s
C) ½ mv²
D) W/t

Power is equal to:
A) Work × Time
B) Work / Time
C) Force × Acceleration
D) Energy × Time

Which energy does a flying bird have?
A) Only kinetic
B) Only potential
C) Both kinetic and potential
D) None

Ø  Quick Revision Tip:

👉 Learn all formulas — KE, PE, Work and Power. Understand examples like dam water, moving car & machine work rate.

Ø  Next Chapter:

👉 Coming Up: Gravitation — Key Points + Explanation + MCQs