Page 3 - Force 10
P. 3
Unit 1: Gravitational force 1
Force: Force is an external agent that changes or Effects of gravity in earth:
tends to change the state of rest or motion in a
straight line. Its unit is Newton (N). ❖ Stability of bridges, large buildings & all
of us.
F = m.a (mass of an object * acceleration) ❖ Flowing of river.
❖ Atmosphere around the earth.
Gravitation: The mutual force of attraction ❖ Change in weather etc.
between any two objects towards their centers in
the universe is called gravitation. Acceleration due to gravity (g): The rate of
change of velocity of an object with unit time
Universal Gravitational constant (G): It is the while falling freely towards the center of planet
gravitational force between two unit masses or satellite as an effect of gravity is called
which are separated by a unit distance. Its value acceleration due to gravity. Its unit is m/s .
2
is
Acceleration due to gravity on the earth is 9.8
-11
2
G = 6.67 × 10 Nm kg -2
2
m/s . It means a freely falling object increases
Newton’s law of gravitation: “The force of its velocity with the rate of 9.8 m/s in every
gravitation between two bodies in the universe is second of time while falling towards the
directly proportional to the product of their center of earth.
masses and inversely proportional to the square
of the distance between their centers”.
=
Where, G = Gravitational constant,
d = Distance between two object from their
center
F=Gravitational force between two objects
Weight (W): The force of gravity experienced
m 1, m 2, = mass of an two objects resp. by the total mass of an object is called weight.
Gravity: The resultant force with which the Its unit is Newton (N). And mass is the total
planet or satellite attracts different objects quantity of matter present in an object.
towards their center is called gravity. Weight (W) = mass (m) *acceleration due to
Value of gravity: gravity (g) W = m.g
Jupiter = 25 N E.g. The weight of a ball is 20 N. It means that
ball experiences the force of gravity of 20 N
Moon = 1.67 N towards the center on the surface of which it is
kept.
Pole of earth = 9.83 N
Equator of earth = 9.78 N
Do you know?
The force of gravity 100 km (60 miles) above the earth is just 3% less than on the Earth’s surface.
