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# Unit 3: Gravity

In this chapter, we will explore what gravity is and how it keeps all of us stuck to earth, and our solar system together. We will also explore pressure in fluids and what makes things float.

## Universal law of gravity

What keeps our solar system together? What keeps a galaxy together? What makes things fall down on earth? The answer to all of them is gravity. In this lesson we will explore one single law, that is obeyed by everything in the universe.

## Free fall & Acceleration due to gravity:

Galileo figured out, all things fall at the same rate. But why? And at what rate do they fall? What does this depend on? By using the law of gravity we can answer all these questions.

## Motion of objects in the influence of gravitational force of earth

In this lesson, we solve some numerical on free falling bodies.

## Thrust & pressure

Why do sharp things easily prick and cut, even by applying moderate force? Because they produce high pressure. In this lesson, we will learn what the words pressure and thrust mean.

## Pressure in liquids & Archimedes principle

As submarines go deeper in the water they get crushed by water pressure. It's the same pressure that lets ship float. In this lesson, we will explore this pressure in liquids and learn about Archimedes principle of floatation

## Density and condition for floating

A tiny nail sinks in water, yet a massive ship made of the same nail can float. How? In this lesson, we will explore what density is and how it decides whether something floats or sinks in fluids.

## Relative density

In this lesson, we will learn what relative density is and how it helps predict whether something floats or sinks.