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A planet moves around Sun in an elliptical orbit of eccentricity e. The ratio of the velocity at perigee Vp and at apogee Va is given by

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Important Questions on Gravitation

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If a satellite has to orbit the earth in a circular path every 6hrs, at what distance from the surface of the earth should the satellite be placed (radius of earth =6400 km )
(Assume GM4π2=8×1012Nm2 kg-1,, where G and M are gravitational constant and mass of earth and 101/3=2.1 )
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A planet revolves in an elliptical orbit around the sun. The semi-major and semi-minor axes are a and b. Then, the square of time period T is directly proportional to-

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A planet is revolving around the sun in which of the following is correct statement?

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An artificial satellite of mass m is moving along an elliptical path around the earth. The areal velocity of the satellite is proportional to
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India's Mangalyan was sent to the Mars by launching it into a transfer orbit EOM around the sun. It leaves the earth at E and meets Mars at M. If the semi-major axis of Earth's orbit is a e = 1.5 × 1 0 1 1 m  , that of Mar's orbit a m = 2.28 × 1 0 1 1 m , taking Kepler's laws, give the estimate of time for Mangalyan to reach Mars from Earth.
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A planet is revolving round the sun of mass M in an elliptical orbit with semi-major axis a. The speed of the planet when it is at a distance r from the sun is, (G - Universal gravitational constant)
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A geostationary satellite orbits around the earth in a circular orbit of radius 36000 km. Then, the time period of a sky satellite orbiting a few 100 km above the earth's surface R=64000 km will approximately be
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A small satellite is in elliptical orbit around the earth as shown in figure. L denotes the magnitude of its angular momentum and Kdenotes its kinetic energy. If 1 and 2 denote two positions of the satellite, then

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The figure shows an elliptical path ABCD of a planet around the sun S such that the area of triangle CSA is 14 the area of the ellipse. (see figure) with DB as the major axis, and CA as the minor axis. If t1 is the time taken for the planet to go over path ABC and t2 for path taken over CDA then:

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If the distance between sun and earth is d, then the angular momentum of earth around the sun is proportional to
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Assume that the earth moves around the sun in a circular orbit of radius and there exists a planet that also moves around the sun in a circular orbit with an angular speed twice as large as that of the earth. The radius of the orbit of the planet is,

Assume radius of orbit of planet earth to be R.

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A star mass M (equal to the solar mass) with a planet (much smaller than the star) revolves around the star in a circular orbit. The velocity of the star with respect to the centre of mass of star-planet system is shown below:

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The radius of the planet's orbit is closest to (1 AU=Distance Earth and Sun)

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Many exoplanets have been discovered by the transit method, where in one monitors, a dip in the intensity of the parent star as the exoplanet moves in front of it. The exoplanet has a radius R and the parent star has radius 100 R. If I0is the intensity observed on earth due to the parent star, then as the exoplanet transits
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Earth revolves round the sun in a circular orbit of radius R. The angular momentum of the revolving earth is directly proportional to
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A satellite of mass M is revolving in circular orbit of radius r around the earth. Time of revolution of the satellite is
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A planet revolving in elliptical orbit has :

A. a constant velocity of revolution.

B. has the least velocity when it is nearest to the sun.

C. its areal velocity is directly proportional to its velocity.

D. areal velocity is inversely proportional to its velocity.

E. to follow a trajectory such that the areal velocity is constant.

Choose the correct answer from the options given below:

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According to Kepler's law, the time period of a satellite varies with its radius as
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A satellite is in an elliptical orbit around a planet P. It is observed that the velocity of the satellite when it is farthest from the planet is 6 times less than that when it is closest to the planet. The ratio of distances between the satellite and the planet at closest and farthest points is :
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Kepler's third law states that the square of the period of revolution T of a planet around the sun is proportional to the third power of the average distance r between sun and planet i.e., T2=Kr3, here K is constant. If the masses of sun and planet are M and m respectively then as per Newton's law of gravitation force of attraction between them is F=GMmr2, here G is gravitational constant. The relation between G and K is described as:
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Two satellites S1 and S2 are revolving around a planet in the opposite sense in coplanar circular concentric orbits. At time t=0, the satellites are farthest apart. The periods of revolution of S1 and S2 are 3 h and 24 h respectively. The radius of the orbit of S1 is 3×104 km. Then the orbital speed of S2 as observed from