3.1 Newton’s Universal Law of Gravitation 3.1.1 Explain Newton’s Universal Law of Gravitation: F = 퐺푚1푚2푟2 3.1.2 Solve problems involving Newton’s Universal Law of Gravitation for: (i) two static objects on the Earth (ii) objects on the Earth’s surface (iii) Earth and satellites (iv) Earth and Sun

1. Gravitation
KSSM TINGKATAN 4 | DLP

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answer these questions.
We are going to
What are Newton’s
Universal Law of Gravitation
and Kepler's’ Laws?
01
Why we need to know the
values of the gravitational
acceleration of planets in the
Solar System?
02
03 How do man-made
satellites help to
improve human life?
05

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Success
Criteria
(Learning
standard)
01
Students will be able to
state and write Newton’s
Universal Law of Gravitation
Students will be able to
state, explain and write
Kepler’s Law
Students will be able to
explain about satellites
orbiting.
Students will be able to
solve problems about
escape velocity
explain these.
We will be able to
02
03
04

4. There are various types
of man-made satellites
revolving in their
respective orbits in outer
space.
Satellites are invented
for:
• communication
purposes,
• weather forecasts and
• Earth observations.
Why are these satellites able to
revolve in their respective orbits?

5. Ibn al-Haytham wrote
about gravity before
Newton!
Ibn al-Haytham’s name is frequent. Talented man he
was. Father of ‘History of Science’, George Sarton
indirectly writes that Newton was influenced by ibn
al-Ibn al-Haytham and, Isaac Newton did keep a copy
of ibn al-Haytham’s magnum opus, Kitab al-
Manazir (Book of Optics) in his personal library.
This Photo by Unknown Author is licensed under CC BY-SA
This Photo by Unknown Author is licensed under CC BY-SA

6. This Photo by Unknown Author is licensed under CC BY-SA
Then, it is said, in 1667, the scientist, Isaac Newton,
observed an apple which fell vertically to the ground
and the movement of the Moon around the Earth.
From what he read, he subsequently concluded that a
force of attraction not only exists between the Earth
and the apple but also between the Earth and the
Moon.

7. Curiosity Curiosity about the universe has
encouraged scientists to launch
spaceships and satellites which can
overcome the Earth’s gravity.
At present, there are spaceships
which are moving far away from
the Earth.

8. This Photo by Unknown Author is licensed under CC BY-NC-ND
Such spaceships enable
photographs of planets to be
taken to benefit scientific
inventions and technology.

9. Activity 3.1
A person who jumps up will return to the ground.
What force causes the person to return to the ground?
Air molecules remain in the atmosphere without escaping to
outer space. What force acts between the molecules in the
atmosphere and the Earth?
The Moon revolves around the Earth without drifting away
from its orbit. The Earth exerts a pulling force on the Moon.
Does the Moon also exert a force on the Earth?
These are situations involving gravitational force between two
bodies. Surf the web now to gather relevant information. Some
of you will be asked to give your findings about these questions.

10. Presentation
#Wheelofnames

11. Gravitational force
known as universal force
∵ it acts between
in the universe.
This Photo by Unknown Author is licensed under CC BY-NC-ND
any two bodies

13. Info
01
Gravitational force exists
between two bodies.
Both bodies experience
gravitational force of the
same magnitude.
02
Why does a fallen leaf move
towards the ground?
Both the leaf and the Earth experience the same
gravitational force.
This causes the leaf and the Earth to move towards
one another.
As the mass of the Earth is very much larger than
the mass of the leaf, gravitational force does not
have an apparent effect on the Earth’s movement.
As such, we only observe the leaf falling to the ground.

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between two bodies:
Relationships
Gravitational force is directly
proportional to the product
of the masses of the two
bodies, that is F ∝ m1m2
01
Gravitational force is inversely
proportional to the square of
the distance between the
centres of the two bodies,
that is F ∝ 1/r 2
02
05
Newton’s Universal Law of
Gravitation.

17. Newton’s Universal Law of Gravitation.
states that the gravitational force between two bodies is directly
proportional to the product of the masses of both bodies and
inversely proportional to the square of the distance between the
centres of the two bodies.
F = G
m1
m2
𝑟2
G = gravitational constant (G = 6.67 × 10–11 N m2 kg–2)
*G can be determined through experiment.
Two bodies of masses m1 and m2 that are
separated at r, experience a gravitational
force of F respectively.

19. Activity 3.2
Aim: To solve problems involving Newton’s Universal Law of
Gravitation for two bodies at rest on the Earth.
Discussion:
1. How do the masses of two bodies influence the gravitational
force between them?
2. What is the effect of distance between two bodies on
gravitational force between them?
3. Why is the magnitude of gravitational force between you and
your partner small?
60
60
70
50
7.01 X 10-8
1.75 X 10-8
5.01 X 10-8
1.25 X 10-8
The larger the mass of the body, the larger the
gravitational force.
Gravitational force decreases when the distance
between the two bodies increases.
Small masses relative to the Earth.