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Gravitational Field (gravitational field strength (Similarities between F…
Gravitational Field
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Gravitational Potential
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Since V= W/m, V= (-GM)/r
*negative sign is a must
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Why negative
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But the potential at infinity=0, which is maximum
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Energy of a satellite
it is in the earth's gravitational field, hence it has gravitational potential energy
Ep=(-GMm)/r
it moves with velocity V, so it has kinetic energy, Ek=1/2mv^2= 1/2 (GMm)/r
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Density of Earth
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M=(gR^2)/G, ρ=m/v,
so ρ=(gR^2)/G x 3/(4πR^3)
=(3g)/(4πGR)
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Types of orbit
Stationary orbit
Satellite with a fixed radius, hence centre of its orbits @ the centre of earth
Geostationary orbits
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-centre of its orbit @ centre of earth
-period=24hr per rotation
-direction of rotation= west to east
-satellite must be placed at 3600 km from the surface of earth exactly at the plane of equator
Escape velocity
the minimum velocity for an object to escape completely from the planet's gravitational attraction due to KE alone
1/2mv^2=(GMm)/r