Work and Energy Definition, Types, Examples & Uses

Work and Energy

Subject: General Science

Book: NCERT Science Class 9

Work is done when a force is applied to move an object.
- **Work Formula**:
- W = F × d × cosθ
- **Types of Work**:
- Positive work (Force in direction of motion).
- Negative work (Force opposite to motion).
- **Energy**:
- Kinetic Energy: Energy due to motion (KE = ½mv²).
- Potential Energy: Energy stored due to position (PE = mgh).
- **Law of Conservation of Energy**:
- Energy cannot be created or destroyed, only transformed.

**Possible Exam Questions:**
1. What is the difference between kinetic and potential energy?
2. Explain the law of conservation of energy with an example.
3. How is work done calculated? Provide numerical examples.
4. Why is no work done when a person pushes a wall?
5. Derive the formula for kinetic energy.