# Review of Gravitation

### Review Test

The planets orbit the sun in:

The eccentricity of an ellipse with semimajor axis length 10 meters and semiminor axis length 5 meters is:

A planet sweeps out an area equal to half the total area of its orbit in 180 days. Its orbital period is:

If the circular orbit of a planet is reduced in radius to 1/8 th of its original value, its period is now, what fraction of its old period, T old ?

Which is the following orbits are possible around the earth:

Various orbits around the earth.

An eccentricity of zero means the orbit is:

An eccentricity of 1.5 means the orbit is:

If a satellite is orbiting the earth at radius 6×106 meters above the center of the earth. What is its period? (The mass of the earth is 5.98×1024 kilograms).

Kepler's Second Law is an expression of:

The direction of the force due to gravity between two point objects located at and is given by:

g equals:

The gravitational force that a spherical shell of mass 102 kilograms exerts on a 5 kilogram mass at its center is:

If you can throw a ball 10 meters into the air on earth, approximately how high would you me able to throw it on the moon (mass of the moon is 7.35×1022 kilograms and its radius is 1700 kilometers).

A planet of mass 6×1025 kilograms, orbiting the sun (mass = 1.99×1030 kilograms) has a velocity of 50 kilometers/sec. What is its rate of change of angular momentum at this point:

The correct ordering of the forces in terms of their relative strength, beginning with the strongest is: I) Gravity II) Strong Nuclear Force III) Electromagnetic Force IV) Weak Nuclear Force.

A particle of mass 2 kilograms orbits the sun (mass = 1.99×1030 ) parabolically. Its velocity very far away from the sun is:

Two stars of equal mass exert a gravitational force on one another. This will cause them to:

If it is desirable to give a rocket the maximum tangential velocity on its launch, then the best launch site would be:

The total energy of a circular orbit is:

Which of these can not be deduced from Kepler's Laws: I) orbits may be circular, II) The force between two planets goes as 1/r 2 , III) Gravity is a conservative force.

Which of the following has the smallest escape velocity:

The gravitational potential energy of a mass 100 kilometers from the earth, compared to the same mass at the surface is:

The gravitational potential at a point 100 kilometers above the earth's surface is:

The units of G are:

Put these orbits in order of increasing energy: I) parabola II)cicle III) hyperbola IV) ellipse

The only orbit to have a positive total energy is:

A satellite in low-earth orbit ( r r e ), has a period of:

The tides are caused by which of the following: I) The moon II) The sun III) The rotation of the earth.

The escape velocity from the earth is approximately (mass of the earth is 5.98×1024 kilograms and its radius is 6.38×106 meters):

I) Newton, II)Einstein, III) Copernicus, IV) Kepler. The correct order in which these scientists lived is:

Which is true of the gravitational force between the earth and the moon is: I) equal and opposite II) zero at some point between the two.

The minimum radius of orbit for a planet with ε = 0.75 is:

What is the semimajor axis length of an elliptical earth orbit with apogee 1.4×107 meters and perigee 1.2×107 meters?

The gravitational force between two objects is: I) Conservative II) Independent of intervening objects III) Central.

Gravitational field between two masses
In the arrangement shown in , a mass exactly half way between the two masses shown would have a gravitational potential energy of:

A planet in an elliptical orbit travels fastest at its:

An experiment to determine G was successfully performed by:

Which of these is an expression of angular momentum: I) × II) mvr sinθ III) 1/2×rv sinθ .

Escape velocity depends on:

The total energy of Io, orbiting Jupiter at a distance of 4.22×106 meters is (mass of Jupiter is 1.9 ×1027 kilograms, mass of Io is 8.9×1022 kilograms):

Which of the following is an expression of the principle of equivalence?

To which of the following could Kepler's Laws be applied? I) a comet, II) a binary star system, III) a projectile on the earth.

The gravitational potential energy can be defined as:

For a circular orbit, which of the following is true for the kinetic energy, T?

An 80 kilogram astronaut is in a spaceship accelerating upwards 4.9 m/s 2 far away from any star or planet. His apparent weight as measured by some scales in the spaceship would be:

Assuming the earth is in a circular orbit about the sun, what is the speed of the earth (the mass of the sun is 1.99×1030 kilograms and the earth- sun distance is 150×109 meters).

If the ratio of a planet's perihelion distance to aphelion distance is 0.75, then the ratio of its greatest to least velocity on its orbit is:

If the orbits of Venus and the Earth are both circular, with the period of the earth orbit 1 year and the period of Venus, 0.615 days, what is the ratio of the earth's orbit to Venus's orbit?

The correct ordering, in terms of increasing numerical value of the kinetic, potential and total energies for a circular orbit is:

A binary star system has two stars of masses m 1 and m 2 , orbiting about their common center of mass with radii r 1 and r 2 respectively. What is the square of the period of their orbit?

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