Gravitation

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GRAVITATION
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What is gravitation ?

• Gravitational force is a universal force and it
  acts not only between two objects on the earth
  but also between any two objects in the universe.
• Gravitation is a natural phenomenon by which all
  things with mass or energyincluding planets,
  stars, galaxies, and even lightare brought
  toward (or gravitate toward) one another.

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Law of gravitation

• Newton's law of universal gravitation states that
  every particle attracts every other particle in
  the universe with a force which is directly
  proportional to the product of their masses and
  inversely proportional to the square of the
  distance between their centers.
• FG m1m2/d2

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GRAVITONS

• Basic particles of Gravity.
• Yet to be discovered
• In theories of quantum gravity, the graviton is
  the hypothetical quantum of gravity, an
  elementary particle that mediates the force of
  gravity.

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Circular motion centripetal force
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KEPLERS LAW

• The orbit of a planet is an ellipse with the Sun
  at one of the foci.
• The line joining the planet and the Sun sweeps
  equal areas in equal intervals of time.
• The square of its period of revolution around the
  Sun is directly proportional to the cube of the
  semi major axis of a planet from the Sun.

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1ST LAW
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2ND LAW
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3RD LAW
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Earths gravitational acceleration

• Standard value is 9.807 m/s2
• Change along the surface of Earth.
• Change along variation in height.
• Change along depth.
• gGM/r2

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MASS VS WEIGHT

• WEIGHT

• MASS

• Amount of matter present in the object.
• Value is same everywhere.
• It is a scalar quantity.

• The force with which the earth attracts the
  object.
• Value changes with respect to place on Earth.
  (FWmamg).
• It is a vector quantity directed towards the
  centre if Earth.

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Free fall

• When an object moves under the influence of the
  force of gravity alone, it is said to be falling
  freely.
• But its not a true free fall, since motion is
  opposed by friction with air.
• Terminal velocity.

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Gravitational potential

• The energy stored in an object because of its
  position or state is called potential energy.
• For an object of mass m, at a height h from the
  ground is mgh and on the ground it is zero.
• For large value of h, value of g decreases with
  increase in h.
• Gravitational potential energy is given by
  -GMm/(Rh)

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Escape velocity

• Escape velocity is the minimum speed needed for a
  free object to escape from the gravitational
  influence of a massive body.

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Thank you