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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/kg2
b. N*m2/kg
c. N*kg2/m2
d. N*m2/kg2

24. The value of K for planets around our sun is 3.35x1018 m3/s2. If Neptune’s orbit has an average radius of 4.5x1012 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=6.67x10-11N*m2/kg2.

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 102323 and a radius of 3.43x106 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 r3/T2=3.35x1018 m3/s3. 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 1011 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.


If you have any questions, please email Ms. Cummings