1. Why We Study Work, Energy and Power
Whenever something moves, stops, speeds up, or slows down, forces are involved. These forces can transfer energy and cause objects to do work. To understand this clearly, we use the ideas of work, energy, and power.
These three concepts help explain how everyday actions — like lifting a bag, riding a bicycle, or switching on a fan — actually happen in physics.
1.1. Connection Between Work, Energy and Power
These ideas are closely related:
- Work tells us how much energy is transferred.
- Energy tells us the ability to do work.
- Power tells us how fast the work is done.
2. Understanding Work in a Simple Way
In everyday language, we say we are ‘working’ even when we are just thinking or studying. But in physics, work has a very specific meaning: a force must move an object.
2.1. Examples of Work in Real Life
- Lifting a school bag from the floor.
- Pushing a trolley in a shop.
- Pulling a chair across the room.
2.2. Examples Where No Work Is Done (In Physics)
Even if you apply force, if nothing moves, no work is done:
- Pushing a wall.
- Holding a heavy box without moving it.
3. Understanding Energy
Energy is the ability to do work. Every moving, glowing, heating, or lifting process involves energy. Without energy, no work can be done.
Energy appears in many forms — motion energy, heat energy, electrical energy, and more.
3.1. Examples of Energy Around Us
- A moving car has kinetic energy.
- A stretched rubber band stores potential energy.
- A battery contains chemical energy.
- The Sun provides solar energy.
4. Understanding Power
Power tells us how fast work is done. Two people may do the same amount of work, but the one who does it faster has more power.
4.1. Simple Examples of Power
- Two students climb the same stairs. Whoever reaches first has used more power.
- An electric motor with higher wattage can do work faster.
- A sprinter shows more power than a jogger.
5. How These Ideas Work Together
Work, energy and power are linked in every physical activity:
- Energy allows work to be done.
- Work happens when a force moves an object.
- Power tells us how quickly the work is done.
5.1. Real-Life Example: Riding a Bicycle
When you pedal, your muscles use stored energy. This energy becomes work as you push the pedals and move the cycle. If you pedal faster, you are using more power.