2. GRAVITATION :
Gravitational force is
the force of attraction on a body by
earth.
Ø Example - Leaves and fruits fall from
a tree downwards towards the
ground due to the gravitational pull.
3. CENTRIPETAL FORCE :
The force that act on a object moving in a circular path and directed towards the centre
4. UNIVERSAL LAW OF GRAVITATION :
Every object in the universe attracts every other object with a force, which is directly proportional to their
product of mass and inversely proportional to the square of the distance between them.
Formula :
6. IMPORTANCE OF UNIVERSAL LAW OF GRAVITATION :
The force that binds us to the earth.
The motion of the moon around the sun
The motion of planets around the sun
The tides due to the moon and the sun
7. KEPLER'S LAW :
THREE LAWS DERIVED BY KEPLER ARE :
KEPLER'S FIRST LAW : { LAW OF ELLIPISE }
All planets travel in
elliptical orbit with the sun as its one foci
8. KEPLER'S LAW :
KEPLER'S SECOND LAW : { LAW OF EQUAL AREA }
The line joining the sun to a
planets sweeps equal areas in equal interval of time.
9. KEPLER'S LAW :
Kepler's third law of motion : { law of harmonies }
The square of the time period of revolution of a planet around
the sun in its elliptical orbit is directly proportional to the cube of the semi major axis of the
ellipse
10. FREE FALL :
When a object falls towards the earth under the gravitational force. Then the body is said to
be in free fall.
ACCELERATION DUE TO GRAVITY :
Acceleration of a body during free fall towards a celestial body is called acceleration due to
gravity
12. MASS :
Mass of an object = Measure of its inertia
Greater mass = Greater inertia
Mass of an object is constant and does not change from place to place
The SI unit of Mass is kilogram { KG }
It is a scalar quantity
13. WEIGHT :
The force of attraction of the earth on an object is known as the weight of an object
The SI unit of latest Newton
It is a vector quantity
Weight depends on its location
The formula of weight is w = mg
14. WEIGHT OF AN OBJECT ON THE MOON :
• The weight of an object on the earth is the force with which the earth attracts the object.
M = mass of an object
Wm = weight of the object on moon
Mm = mass of moon
Rm = radius of moon