A geostationary satellite

Geostationaryjava3DsideviewA geostationary satellite is a satellite in geostationary orbit, with an orbital period the same as the Earth’s rotation period. The geostationary orbit is a circular orbit directly above the Earth’s equator.

How high above the Earth’s surface must the geostationary satellite be placed into orbit?

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How long would it take to fall through the center of the Earth?

We have a hole that leads straight through the center of the Earth. We neglect air resistance and assume that the Earth has uniform density ρ. How long would it take to fall through the center of the Earth and reach the other side of the planet?

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What is the surface temperature of the planet?

A planet of radius r and mass M has a homogeneous atmosphere (density independent of height). The atmosphere has a height h and the atmosphere’s gas has a molar mass μ.
What is the surface temperature of the planet?

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Why Is The Milky Way A Spiral?


More than two-thirds of the galaxies are disc shaped. Most disc galaxies have spiral arms and are called spiral galaxies. Continue reading

If the orbital speed was doubled

Each planet has its own orbital speed. If the orbital speed was doubled, the planet would

a) enter into a closer orbit around the Sun.
b) enter into a far orbit around the Sun.
c) warm up.
d) escape the Sun.

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A planet X around a star S

The diagram shows an approximate orbit of a planet X around a star S.


Which of the following statements is false?

(a) The planet moves in an ellipse with the star at one focus.
(b) The planet moves at the same speed at points A and C.
(c) The planet moves fastest at point D.
(d) The potential energy of the planet changes during the orbit.


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If the solar system were reduced

Solar System (artist's impression) If all the linear dimensions of the solar system were reduced in some proportion, then what will be the length of Earth’s year?


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