Kepler’s first law of planetary motion says that the paths of the planets are

A.A. ParabolasParabolas

B.B. HyperbolasHyperbolas

C.C. EllipsesEllipses

D.D.CirclesCirclesAns: C

A planet orbiting the sun

a.a. Maintains the same Maintains the same distance from the sundistance from the sun

b.b. Moves at a constant speedMoves at a constant speedc.c. Moves faster when it is Moves faster when it is

farther from the sunfarther from the sund.d. Moves faster when it is Moves faster when it is

closer to the suncloser to the sun

Ans: D

Newton’s law of universal gravitation states that the gravitational force between two bodies is

A.A. Directly proportional to the distance Directly proportional to the distance between thembetween them

B.B. Directly proportional to the square of Directly proportional to the square of the distance between themthe distance between them

C.C. Inversely proportional to the distance Inversely proportional to the distance between thembetween them

D.D. Inversely proportional to the square of Inversely proportional to the square of the distance between themthe distance between them

Ans: D

Two moons orbit a planet. The average orbital radius of the outer moon is 1.8 times that of the inner moon. The orbital period of the outer moon is

aa.. 0.56 times that of the inner moon 0.56 times that of the inner moon

b.b. 1.8 times that of the inner moon1.8 times that of the inner moon

c.c. 2.4 times that of the inner moon2.4 times that of the inner moon

d.d. 5.8 times that of the inner moon5.8 times that of the inner moon

Ans: C

The center of mass A of an object is 0.48 m from the center of mass B of another object. How much greater would the gravitational force between the two masses be if their centers were only 0.12 m apart?

A.A. 2 times greater2 times greater

B.B. 4 times greater4 times greater

C.C. 8 times greater8 times greater

D.D. 16 times greater16 times greater

Ans: D

The mass of Earth is approximately 6.0 x 1024 kg. What would the acceleration due to gravity be on the surface of planet Q which has a mass of 5.0 x 1024 kg and a radius equal to the radius of Earth?

A.A. 6.8 m/s6.8 m/s22

B.B. 8.2 m/s8.2 m/s22

C.C. 9.8 m/s9.8 m/s22

D.D. 12 m/s12 m/s22

Ans: B

Two satellites orbit the Earth at the same altitude in circular orbits. One satellite has a mass of 450 kg, and the other has a mass of 150 kg. The orbital speed of the larger satellite is

A.A. The same as the speed of the smaller The same as the speed of the smaller satellitesatellite

B.B. 1.7 times the speed of the smaller satellite1.7 times the speed of the smaller satellite

C.C. 3.0 times the speed of the smaller satellite3.0 times the speed of the smaller satellite

D.D. 9.0 times the speed of the smaller satellite9.0 times the speed of the smaller satellite

Ans: A

What is the acceleration due to gravity at an altitude of 4.0 Earth radii above the surface of Earth?

A.A. 0.39 m/s0.39 m/s22

B.B. 2.0 m/s2.0 m/s22

C.C. 2.4 m/s2.4 m/s22

D.D. 9.8 m/s9.8 m/s22

Ans: A

Two cans of soda are next to each other on a table. If the mass of each can of soda is 0.355 kg and their centers are 0.08 m apart, what is the gravitational force between them?

A.A. 20 N20 N

B.B. 2.0 x 102.0 x 10-3 -3 NN

C.C. 1.3 x 101.3 x 10-9-9 N N

D.D. 1.3 x 101.3 x 10-13 -13 NN

Ans: C

Suppose that in the distant future, astronauts are exploring a planet in another solar system. They find that the radius of the planet is 7.8 x 103 km and the acceleration due to gravity on its surface is 12.3 m/s2. What is the mass of the planet?

A.A. 1.1 x 101.1 x 101919 kg kg

B.B. 6.0 x 106.0 x 1024 24 kgkg

C.C. 1.1 x 101.1 x 102525 kg kg

D.D. 6.0 x 106.0 x 102626 kg kg

Ans: C

A satellite orbits Earth 3,250,000 m above the Earth’s surface. What is the satellite’s orbital speed?

A.A. 6440 m/s6440 m/s

B.B. 7330 m/s7330 m/s

C.C. 7920 m/s7920 m/s

D.D.1110 m/s1110 m/s

Ans: A

A satellite orbits a planet in a circular orbit. If the orbital radius is 7.8 x 108 m and the time required for a complete revolution is 3.5 x 106 S, what is the orbital speed?

A.A. 140 m/s140 m/s

B.B. 2200 m/s2200 m/s

C.C. 4500 m/s4500 m/s

D.D. 7000 m/s7000 m/s

E.E. 1400 m/s1400 m/s

Ans: E