Chapter
8 Review
1. ____________ was best known as an accurate observer of the heavens.
2. ____________ an excellent mathematician, formulated three laws of planetary
motion.
3. The paths of the planets around the sun are ____________.
4. An imaginary line between planet and the sun sweeps out equal ____________
in equal periods of time.
5. The average ____________ of a planet’s orbit cubed divided by
the planet’s period squared is equal to a constant.
6. ____________ was the first person to believe strongly that the behavior
of all material bodies is governed by the same universal laws.
7. Every body in the universe attracts every other body with a force that
varies ____________ with the product of the masses.
8. Gravitational attraction varies ____________ with the square of the
distances between masses.
9. Newton was able to use information concerning the moon to test and
verify his ____________.
10. ____________ determined the numerical value for the universal gravitational
constant.
11. ____________ is another name for the attractive gravitational forces
between an object and the earth.
12. The ____________ of gravity is the same for all objects near the surface
of the earth.
13. The ____________ of an object varies inversely with the square of
its distance from the center of the earth.
14. ____________ first proposed the concept of gravity as a peculiarity
of space itself.
15. Whose work was part of the basis for Newton’s law of gravitation?
a. Aristotle
b. Roemer
c. Kepler
d. Einstein
16. Planets move around the sun in ____________ orbits.
a. Elliptical
b. parabolic
c. circular
d. Hyperbolic
17. According to Kepler’s second law, a planet must move fastest
when it is ____________ the sun.
a. closest to
b. farthest from
c. at its average distance from
18. If the earth is one astronomical unit of distance from the sun and
has a period of one year, approximately how far is Jupiter from the sun
in astronomical units? Jupiter has a period of 12 years.
a. 2
b. 5
c. 10
d. 15
19. The gravitational constant was measured by
a. Kepler
b. Newton
c. Cavendish
d. Einstein
20. You weigh 526 N on Earth. Planet X has twice the mass of Earth and
twice the radius of Earth. What is your weight in newtons on planet X?
a. 1/5000 N
b. 200 N
c. 5000 N
d. 25,000 N
21. If a satellite moves in a circular orbit around a planet, the satellite
has a constant
a. momentum
b. velocity
c. acceleration
22. An object weighing 40 N on the earth’s surface would weight
only 10 N when its distance from the center of the earth is
a. doubled
b. halved
c. tripled
d. quadrupled
23. Which of the following are the correct units for G, the gravitational
constant?
a. N*m/kg^{2}
b. N*m^{2}/kg
c. N*kg^{2}/m^{2}
d. N*m^{2}/kg^{2}
24. The value of K for planets around our sun is 3.35x1018 m^{3}/s^{2}. If
Neptune’s orbit has an average radius of 4.5x10^{12} m, calculate the
period of Neptune.
25. The gravitational force between two electrons 1.00 m apart is 5.42
x 10^{71} N. Calculate the mass of an electron. G=6.67x10^{11}N*m^{2}/kg^{2}.
26. If you weigh 637 N on the earth’s surface, how much would you
weigh on the planet Mars? (Mars has a mass 0f 6.37 x 10^{23}23 and a radius
of 3.43x10^{6} m.)
27. If the distance between two objects is decreased to one fourth the
original distance, what happens to the force?
28. If you double the mass of one object and double the distance between
the centers of the two objects. What happens to the force?
29. If you double the mass of each object and double the distance between
them, what happens to the force?
30. Kepler’s law states that r^{3}/T^{2}=3.35x10^{18} m^{3}/s^{3}. How many years
would it take a planet located four times as far from the sun as the earth
to orbit the sun? The earth’s distance from the sun is 1.5 x 10^{11}
m.
31. A satellite in low Earth orbit is 230 km above the surface. What
is its orbital velocity?
32. Uranus requires 84 years to circle the sun. Find Uranus orbital radius
as a multiple of Earths orbital radius.
