Physics-CBSE

Gravitation

The force of attraction with which Earth pulls objects towards itself

Centripetal force

Force acting towards the centre of a circular path

Centre seeking force

Another name for centripetal force

Universal law of gravitation

Force between two objects is directly proportional to product of masses and inversely proportional to square of distance between them

Direction of gravitational force

Along the line joining the centres of two objects

Formula of gravitational force

F = G(Mm)/d²

Universal gravitational constant

G = 6.67 × 10⁻¹¹ Nm²/kg²

Importance of gravitation (i)

It binds us to the Earth

Importance of gravitation (ii)

Explains motion of moon around Earth

Importance of gravitation (iii)

Explains motion of planets around Sun

Importance of gravitation (iv)

Explains tides due to Moon and Sun

Free fall

Falling of an object under gravitational force alone

Acceleration in free fall

An object falling experiences acceleration

Acceleration due to gravity

Denoted by g

SI unit of g

m/s²

Formula for g

g = GM/R²

Value of g on Earth

9.8 m/s²

Mass

Quantity of matter in a body

Mass is scalar

Has only magnitude

Mass consistency

Does not change from place to place

SI unit of mass

Kilogram (kg)

Mass cannot be zero

Mass of a body is always positive

Weight

Force with which Earth attracts a body

Weight (2)

Acts downwards; has magnitude and direction:is a vector quantity