Akshaj gives a brief overview of Gravity and answer the questions by audience. About the speaker: Akshaj is 11 years old and a proud member of Mango Astronomy club. He is passionate about physics and astronomy.

2. By:Akshaj.J.Gopal
GRAVITY

3. Newton asked his biographer William Stukeley
“ Why should that apple always descend perpendicularly to the ground
? Why should it not go sideways or upwards ? “
He implied that there must be some drawing power in matter and the
sum of all the drawing power of the matter in Earth must be at the
Earth’s center.
The drawing power is directly proportional to the mass. .
E.g. : A person on the moon weighs 6 times less than he is on Earth
because the moon is much less massive.
The drawing power of gravity decreases with distance
E.g. : Satellite drifts too far away from the Earth
NEWTON’S IDEA OF GRAVITY

4. Newton states that every particle attracts every other particle in
the universe with a force that is proportional to their masses.
F = G m1,m2
r^2
G= gravitational constant(6.67408 × 10^-11 m^3 kg^-1 s^-2)
NEWTON’S IDEA
OF GRAVITY

5. Objects with mass distorts space time around themselves just
as weights placed on a rubber sheet make dents in it.
Because that object makes a dent in space time, other objects
tend to roll down towards it.
Einstein proposed that gravity acts at the speed of light. If
this is true then something must be carrying gravity. These
theoretical particles are called Gravitons.
EINSTEIN’S IDEA
OF GRAVITY

6. • Gravity is a force
• Mechanism is unknown
• Acts at a distance
• Moves at infinite speed
• Gravity is tied to mass
• Gravity is geometry
• Mechanism is curvature
• Acts locally
• Moves at light speed
• Gravity is tied to energy
Newton Einstein
NEWTON AND EINSTEIN
ON GRAVITY

7. Albert Einstein's general theory of relativity is one of the
towering achievements of 20th-century physics. Published
in 1916, it explains that what we perceive as the force of
gravity in fact arises from the curvature of space and
time.
Earth’s mass bends
the space-time fabric
GENERAL THEORY OF
RELATIVITY

8. Is the sphere of gravitational influence
around a body in which satellites are usually found orbiting
This is the area where satellites a can maintain orbit without
falling into the body or drifting away from it
It was discovered by George William Hill.
HILL RADIUS

9. The distance within the gravitational field of a large
body which is strong enough to prevent any smaller body, from
being held together and in turn disentegrates to form rings. It
was found in 1848 by French astronomer, Edouard Roche .
ROCHE LIMIT

10. exhibits gravitational acceleration so strong that no particles,
electromagnetic radiation and even stars.
General Relativity predicts that sufficently compacted mass can
deform space time to form black holes.
BLACK HOLE

11. Johannes Kepler was a German astronomer and mathematician.
He said
1. All planets move about the sun in elliptical orbits with the
sun at one Foci
2. A radius vector joining any planet sweeps out equal areas in
equal times
KEPLER’S LAWS OF PLANETERY
MOTION

12. The Chandrasekhar limit is the maximum mass a
stable white dwarf star can remain as a white dwarf
star.
The currently accepted value is 1.4 solar
masses(2.765*10^30 kg)
It was named after Indian Astrophysicist Subramanian
Chandrasekhar
CHANDRASEKHAR LIMIT

13. EVOLUTION OF STARS

14. According to Einstein ,starlight passing just before the sun’s
surface bends1/2000th of a degree .this the case for all massive
Gravitational bodies
GRAVITATIONAL LENSING

15. THANK YOU