ASTR 101 CH 4

27) Absolute zero is

A) 0° Kelvin.

42) The orbital period of a geosynchronous satellite is

A) 23 hours 56 minutes.

2) What is the acceleration of gravity of Earth?

A) 9.8 m/s2 downward

45) According to what we now know from Newton's laws, which of the following best explains why Kepler's second law is true?

A) A planet's angular momentum must be conserved as it moves around its orbit.

10) What would happen if the Space Shuttle were launched with a speed greater than Earth's escape velocity?

A) It would travel away from Earth into the solar system.

16) The fact that the Voyager spacecraft continues to speed out of the solar system, even though its rockets have no fuel, is an example of

A) Newton's first law of motion.

12) Which of the following statements is not one of Newton's laws of motion?

A) What goes up must come down.

48) Which of the following best describes the origin of ocean tides on Earth?

A) Tides are caused by the difference in the force of gravity exerted by the Moon across the sphere of the earth.

33) Which of the following scenarios correctly demonstrates the transformation of mass into energy as given by Einstein's equation, E = mc2?

A) When hydrogen is fused into helium, whether in the Sun or in a nuclear bomb, the mass difference is turned into energy.

30) The amount of gravitational potential energy released as an object falls depends on

A) its mass and the distance it falls.

36) Where does the energy come from that your body uses to keep you alive?

B) It comes from the foods you eat.

54) Imagine we've discovered a planet orbiting another star at 1 AU every 6 months. The planet has a moon that orbits the planet at the same distance as our Moon, but it takes 2 months. What can we infer about this planet?

B) It is less massive than Earth.

15) The movement of a pool ball, after being struck by a cue, is an example of

B) Newton's second law of motion.

52) Suppose a lone asteroid happens to be passing relatively near Jupiter (but not near any of its moons), following a hyperbolic orbit as it approaches Jupiter. Which of the following statements would be true?

B) The asteroid's orbit around Jupiter would not change, and it would go out on the same hyperbolic orbit that it came in on.

37) When a rock is held above the ground, we say it has some potential energy. When we let it go, it falls and we say the potential energy is converted to kinetic energy. Finally, the rock hits the ground. What has happened to the energy?

B) The energy goes to producing sound and to heating the ground, rock, and surrounding air.

53) A basketball player jumps to make a basket, and remains in the air for a moment. A sportscaster, talking about the game, then remarks that she has "defied gravity." Which of the following accurately describes the situation?

B) The player produced enough force with her legs to accelerate up into the air, and gravity brought her back down with an acceleration of 9.8 m/s2.

23) Gasoline is useful in cars because it has

B) chemical potential energy.

11) Suppose an object is moving in a straight line at 50 miles/hr. According to Newton's first law of motion, the object will

B) continue to move in the same way until it is acted upon by a force.

24) Which of the following is a form of electrical potential energy?

B) energy coming to your house from power companies

38) According to the universal law of gravitation, the force due to gravity is

B) inversely proportional to the square of the distance between objects.

34) The ultimate source of energy that powers the Sun is

B) mass energy of hydrogen fusing into helium.

4) Momentum is defined as

B) mass times velocity.

18) What quantities does angular momentum depend upon?

B) mass, velocity, and radius

47) The mass of Jupiter can be calculated by

B) measuring the orbital period and distance of one of Jupiter's moons.

26) Of the temperature ranges below, which range represents the smallest range of actual temperature?

C) 50-100° Fahrenheit

32) Considering Einstein's famous equation, E = mc2, which of the following statements is true?

C) A small amount of mass can be turned into a large amount of energy.

17) Changing the orbit of a spacecraft by firing thrusters is an example of

C) Newton's third law of motion.

9) You are standing on a scale in an elevator. Suddenly you notice your weight decreases. What do you conclude?

C) The elevator is accelerating downwards.

35) Which of the following statements correctly describes the law of conservation of energy?

C) The total quantity of energy in the universe never changes.

25) Which object has the most kinetic energy?

C) a 2-ton truck moving 90 km/hr

5) If an object's velocity is doubled, its momentum is

C) doubled.

1) Which of the following is an example in which you are traveling at constant speed but not at constant velocity?

C) driving around in a circle at exactly 100 km/hr

43) The allowed shapes for orbits under the force of gravity are

C) ellipses, parabolas, and hyperbolas.

22) Radiative energy is

C) energy carried by light.

28) What does temperature measure?

C) the average kinetic energy of particles in a substance

39) The force of gravity is an inverse square law. This means that, if you double the distance between two large masses, the gravitational force between them

C) weakens by a factor of 4.

7) If your mass is 60 kg on Earth, what would your mass be on the Moon?

D) 60 kg

44) Each of the following lists two facts. Which pair can be used with Newton's version of Kepler's third law to determine the mass of the Sun?

D) Earth is 150 million km from the Sun and orbits the Sun in 1 year.

14) How does the Space Shuttle take off?

D) Hot gas shoots out from the rocket and, by conservation of momentum, the shuttle moves in the opposite direction.

50) At which lunar phase(s) are tides most pronounced (e.g., the highest high tides)?

D) both new and full Moons

19) A skater can spin faster by pulling her arms closer to her body or spin slower by spreading her arms out from her body. This is due to

D) conservation of angular momentum.

41) According to the universal law of gravitation, if you double the masses of both attracting objects, then the gravitational force between them will

D) increase by a factor of 4.

21) Which of the following is not a unit of energy?

D) kilowatt

20) Which of the following is not a conserved quantity?

D) radiation

31) In the formula E = mc2, what does E represent?

D) the mass-energy, or potential energy stored in an object's mass

46) The center of mass of a binary star system is

D) the point at which the two objects would balance if they were somehow connected.

49) The tides on Earth are an example of

D) the universal law of gravitation.

8) In which of the following cases would you feel weightless?

D) while falling from a roof

3) If you drop a rock from a great height, about how fast will it be falling after 5 seconds, neglecting air resistance?

E) 50 m/s

29) Suppose you heat up an oven and boil a pot of water. Which of the following explains why you would be burned by sticking your hand briefly in the pot but not by sticking your hand briefly in the oven?

E) The water has a higher heat content than the oven.

51) At which lunar phase(s) are tides least pronounced (e.g., the lowest high tides)?

E) both first and third quarters

40) According to the universal law of gravitation, if you triple the distance between two objects, then the gravitational force between them will

E) decrease by a factor of 9.

13) Newton's second law of motion tells us that the net force applied to an object equals its

E) mass times acceleration.

6) As long as an object is not gaining or losing mass, a net force on the object will cause a change in

E) velocity.