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What we will learn in this chapter?
- Name of the chapter is — Work, Energy, and Simple Machines.
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So in this chapter, we will learn about 3 things
- Work
- Energy
- Simple Machines
Lets start with Work first.
What is Work?
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In easy language — when we apply force on an object and the object moves, we say work is done.
Example: We lift a bag from the floor to a shelf. We applied force, the bag moved. So we did work.
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GIF Watch: what is Work
![Introduction - Work, Energy, and Simple Machines - [Teachoo] - Concepts](https://cdn.teachoo.com/91277fe2-8182-4ffb-9505-a291094193dd/animation-for-what-is-work-.-a-short-looping-gif-three-or-four-beats-drawn-in-the-flat-classroom-style-of-the-chapter.-beat-1-in-easy-l.webp)
- In technical language — work done = force applied × displacement in the direction of the force.
- This we will learn in detail in the next section.
What is Energy?
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Energy is the capacity to do work.
In easy language — if something has the ability to get a task done, it has energy.
Example: A moving ball can knock down wickets. So the moving ball has energy.
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GIF Watch: what is Energy
Where does energy come from in daily life?
- Energy required to carry out tasks comes from various sources.
GIF
Watch: where does energy come from in daily life
| Activity | Source of energy |
|---|---|
| Walking | Food |
| Fan rotating | Electricity |
| Car moving | Fuel |
What are Simple Machines?
- Simple machines are devices that help us perform tasks with less effort and more convenience.
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They are the building blocks of many everyday machines.
Example:
- Pulley — to raise a flag
- Inclined Plane — to load a box on a truck
- Lever — seesaw, scissors
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GIF Watch: what are Simple Machines
How are different chapters of physics we have learnt related?
| Chapter | How it connects |
|---|---|
| Chapter 4 — Describing Motion | We learnt about motion — how objects move |
| Chapter 6 — How Forces Affect Motion | We learnt about how force changes motion of object, and Newton's laws |
| Chapter 7 — This chapter | We track work and energy, which gives a simpler and more powerful way to solve the same problems |
Why learn this chapter?
- Newton's laws work well when the force is constant and simple.
- But when forces change with time, or act in complicated ways, applying Newton's laws directly becomes difficult.
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Work and energy give us a simpler and more powerful way to understand such situations.
Example: A child slides down a curvy slide. The force direction changes at every point. Solving this by Newton's laws is very hard, but with energy it takes just one line.
What will we cover in this chapter?
Topics We Will Study
Lets start with Topic 7.1-Work Done by a Constant Force.
