4 Answer Key

ANSWER KEY

Section 3 (p. 21)

1. d 5. b2. e 6. c3. f 7. g4. a8. pulley; wheel and axle; lever; gear9. wedge; screw; inclined plane

10. IMA ! l/h ! 3m/1.5m ! 211. IMA ! Lin/Lout ! 10 m/10 m ! 112. IMA ! rw/ra ! 4cm/1cm ! 4

Chapter 7, The Earth–Moon–Sun SystemSection 1 (p. 23)

1. Ellipse 3. true2. 24 hours 4. magnetosphere5. The northern and southern lights are caused

by the collision of charged particles from thesun and Earth’s atmosphere.

6. The location changes because of changes inEarth’s crust and upper mantle.

7. Earth’s magnetic field is thought to be causedby Earth’s rotation and the movement ofmatter in the core of the Earth.

8. Objects fall towards the center of Earthbecause of gravity.

9. The shadow is curved because Earth is asphere.

10. Earth acts like a giant magnet and attractsthe needle of the compass which is also amagnet.

11. Earth’s oceans absorbed large amounts ofcarbon dioxide.

Section 2 (p. 24)

1. Babylonian symbol for Sun2. 3603. 154. Greenwich, England5. Earth’s rotational north and south poles.6. solar day7. sidereal day8. It appears to move.9. They appear fixed.

10. ecliptic11. because of its rotation, revolution, and the

tilt of its axis.12. It’s higher in the sky.13. It keeps the same direction of tilt.14. equinox15. solsticeSection 3

1. Craters 9. umbra2. Maria 10. Sun3. Regolith 11. gravity4. depression 12. Eclipses5. photographs 13. phases6. iron 14. Moon7. Ice 15. synodic month8. Seismometers

Chapter 8, The Solar SystemSection 1 (p. 27)

1. faster 6. Billions2. heliocentric 7. c3. Earth 8. a4. Earth 9. c5. Day

Section 2 (p. 28)

1. Mars 6. Venus2. Mars 7. Mars3. Venus 8. Mars4. Mars 9. True5. Mercury

10. False; the planet is Mars.11. False; it’s a canyon.12. False; the planet is Venus.13. True14. False; the iron core is much larger than

expected.15. True16. True17. False; the planet is Mercury.18. Small rocky planets formed closer to the Sun

because remaining gas, ice, and dust particlesfrom the nebula that formed the Sun collided

Study Guide and Reinforcement 5

ANSWER KEY

and stuck together. These solid masses thenattracted more particles due to the force ofgravity. The high temperatures close to theSun vaporized the lighter elements, whichalso could have been driven away by solarwinds.

Section 3 (p. 29)

1. asteroid belt 10. Pluto2. Jupiter 11. Uranus3. Ganymede 12. Jupiter4. Saturn 13. Saturn5. Uranus 14. b 6. Neptune 15. d 7. Kuiper Belt 16. a8. Pluto 17. c 9. Neptune 18. e

Section 4 (p. 30)

Possible answers to questions 1–3 1. volcanic vents on the ocean floor (hot, dark,

extreme pressure)2. permafrost areas in northeastern Siberia

(extreme cold)3. mud of Mono Lake, California (dark, lacking

oxygen, large amounts of salt and lye)4. Possible answer: The presence of water might

indicate that extraterrestrial life could surviveand was present at one time on these planetsand moons. Scientists have found that Marsmight have had large amounts of water on itssurface. They also have found evidence thatEuropa, a moon of Jupiter, might have a deeplong-lasting ocean, while the oceans ofGanymede and Callisto, two other moons ofJupiter, might be slowly freezing up.

9. fossil 13. could not10. 40,000 14. Jupiter11. chemical 15. Europa12. Europa 16. Titan

Chapter 9, Heat and States of MatterSection 1 (p. 31)

1. c 6. calorimeter2. a 7. heat3. a 8. potential4. b 9. kinetic5. a 10. faster

Section 2 (p. 32)

1. solid 8. gas2. 10˚C 9. gas3. 50˚C 10. gas4. liquefy 11. liquid5. liquid 12. liquid6. liquid 13. solid7. 110˚C

Section 3 (p. 33)

1. good 6. convection2. conduction 7. convection3. radiation 8. true4. true 9. more5. true

10. silver spoon: Silver is a better conductor ofheat than wood.

11. a red shirt: Darker-colored materials absorbmore heat than lighter-colored materials.

12. a sidewalk in the sun: Dull materials absorbmore radiant energy than shiny materials.

Titan Feature Reason of Interest to Exobiologists

5. Pure water-ice Life on earth needs water topresent survive

6. Hydrocarbons Life on earth is carbon-based.present

7. Cloud of methane Indicates a dynamically present active atmosphere exists

8. Absence of large Indicates internal geologic activityimpact craters that could provide energy needed

for the development of organicmolecules