1. UNIT 3
gravitation

2. Fundamental Forces in nature

3. Newton’s Universal Law of Gravitation
All objects atract each other with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.

4. F is the force of gravity (measured in Newtons, N)
G is the gravitational constant of the universe and is always the same number
M is the mass of one object (measured in kilograms, kg)
m is the mass of the other object (measured in kilograms, kg)
r  is the distance those objects are apart (measured in meters, m)

5. Some features about Gravity
Universal: The same force that makes an object fall on Earth keeps the planets orbiting around the Sun.
As the Gravitational constant (G=6,67 · N·m2/kg2) is very small, gravitational force is only perceptible when at least one of the objects has a great mass.
Gravitational force is always an atractive force.

6. Weight and mass
The weight of an object is the gravitational force acting upon the object due to the acceleration of gravity (g).
While your weight depends on where you are, your mass has always the same value.
w= m·g

7. Activity
Calculate your weight on the Earth, Mercury, the Moon and Jupiter.
You need to calculate the value of the acceleration of gravity in each planet with the data you will find in the next slide.

9. Gravitational force between the Earth and the Sun
The centripetal force that allows the Earth to orbit around the Sun is the Gravitational force.

10. Calculating orbital velocity of a satelite