NAME __________________________________ LAB # _________________________

Astronomy 1001 - Midterm #1 - February 28th Dr. Liliya Williams - Spring 2005

Read Instructions Carefully:

1. MARK THE ANSWERS YOU CHOOSE ON THIS TEST AS IT IS YOUR ONLY

OPPORTUNITY TO CHECK WHICH ANSWERS YOU GOT RIGHT OR

WRONG. This will not be done for you at a later time in the departmental office.

Exams will be returned in your lab, so in order to get your test back, your LAB section

number must be indicated in the space provided above (listing the meeting time and day

of the week for your lab is not sufficient).

2. Print your NAME, ID # and SECTION # on the bubble sheet where appropriate. Your

SECTION # should read 01. All three items are necessary for the proper scoring and

computer transfer of your scores.

3. Use a pencil, make your marks dark and neat, and erase thoroughly.

4. There is only one answer to each question. Choose the best answer.

5. You may use this test for scratch paper.

6. One page (1 side) of notes is allowed for the exam.

I. Multiple Choice (4 pts each)

1. We have seasons on Earth because

(a) the orbit of the Earth is not exactly circular

(b) Earth is closer to the Sun in summer

(d) Earth's axis of rotation is tilted with respect to the ecliptic

(e) Earth's orbit oscillates around the snow line

2. Which of the following Lunar phases will correspond to the highest ocean tide on Earth?

(a) Full

(b) Gibbous

(d) Crescent

(e) None of the above; ocean tides do not depend on Lunar phases

3. Suppose you are an astronaut taking a space walk to fix your space craft with a wrench. Your life-line breaks and the jets on your backpack are out of fuel. How would you return to your craft

safely (without the help of someone else)?

(a) kick your feet in a cyclic motion

(b) fling your arms around in circles

(d) throw the wrench away from the spaceship

(e) admit that you are doomed

4. Pluto and Charon are tidally locked. That means that

(a) their center of gravity is exactly midway between them

(b) in several billion years they will crash into each other

(d) they have the same side (face) to each other at all times

(e) they are both captured comets

5. Uranus's axis of rotation is tilted by 90 degrees (i.e. the axis lies in the plane of the ecliptic). That means that

(a) Uranus has no daytime or nighttime at all

(b) during winter on Uranus it is always night

(d) Uranus is tidally locked with Jupiter

(e) the orbit of Uranus does not obey Kepler's laws

6. Venus rotates on its axis in the opposite direction from other planets because

(a) Venus was formed that way

(b) of differentiation

(d) of Jupiter's tidal forces

(e) any of the above explanations are equally likely

7. The duality of light means Electro-magnetic radiation

(a) cat be at two different places at the same time

(b) can undergo reflection or refraction inside telescopes

(d) can induce atoms to produce emission or absorption lines

(e) can be described by its wavelength or frequency

8. A perfect blackbody at a temperature of 6000K emits more radiation than a perfect blackbody at 5000K

(a) only at Ultra-Violet wavelengths

(b) only at optical wavelengths

(d) at all wavelengths

(e) no radiation is emitted by perfect blackbodies

9. The difference between Ultra-Violet (UV) rays and radio waves is that

(a) UV rays propagate faster in vacuum than radio waves

(b) UV rays can propagate in vacuum while radio waves can travel through air only

(d) UV rays have lower frequency than radio waves

(e) UV rays have larger wavelength than radio wave

10. Moon's chemical composition

(a) is similar to that of Earth's crust

(b) contains large amounts of volatile substances

(d) is dominated by methane and ammonia

(e) has never been analyzed

11. In Lab L, Impacts from Space, the size of the craters in the sand

(a) decreased as mass of ball bearings was increased

(b) increased with the initial height of ball bearings above the sand box

(d) did not depend on the potential energy of ball bearings

(e) was uncorrelated with the mass of the ball bearings

12. Determining the age of the Earth relies on

(a) the radioactive decay of unstable isotopes

(b) nuclear fusion in natural reactors

(d) measuring the rate at which the rivers deposit salt in the oceans

(e) finding fossils from different periods in the Earth's past

13. Ocean tides on Earth occur

(a) twice in a 24 hour period

(b) once in a 24 hour period

(d) with different frequency depending on the season

(e) solely due to gravitational tugs of the Sun

14. An optical and a radio telescope have the same diameter primary (objective). That means

(a) optical telescope has better resolution

(b) radio telescope has better resolution

(d) optical telescope has better magnification

(e) radio telescope has better magnification

15. Kepler`s first law states that

(a) the Earth is the center of the Solar System

(b) the orbit of each planet is an ellipse

(d) the planets undergo uniform circular motion around the Sun

(e) an object at rest or motion remains in that state unless acted upon by a force

16. According to Newton's law of gravity

(a) every object in the universe attracts every other object

(b) the Moon attracts Earth with the same force exerted on the Moon by Earth

squared between the two bodies

(d) the force of gravity increases as the masses of the bodies increase

(e) all of a-d

17. The Sun is at one focus of a planet's elliptical orbit. What is at the other focus of this ellipse?

(a) the orbiting planet

(b) one of the other planets

(d) nothing

(e) the perihelion point

18. The main cause of the slowing down of the rotation of Earth on its axis is

(a) the periodic appearance of comets

(b) tidal friction due to the Moon

(d) friction with Earth atmosphere

(e) none of these; Earth's rotation is actually speeding up

19. Earth's atmosphere has a larger fraction of oxygen molecules than is found in other planets' atmospheres in the Solar System. Why?

(a) biological activity on Earth maintains a high concentration of oxygen gas

(b) UV light from the Sun creates ozone in the upper atmosphere, which chemically breaks down to form oxygen

(c) when the Solar System formed, chemical composition depended on distance from the Sun, and Earth is in the oxygen-rich zone

(d) water on Earth's surface helped draw oxygen from the rocky crust, but the other planets don't have liquid surface water

(e) The reason is not known.

20. Retrograde motion of planets like Mars proved easy to explain once the astronomers accepted that the

(a) Earth was round

(b) planets orbited the Sun

(d) celestial sphere was not real

(e) year is not exactly 365 days long

21. Which one of the following is the correct statement about the Solar System frost line?

(a) if the Sun were a lot hotter the snow line would be closer to the Sun

(b) it runs between the orbits of Mars and Jupiter

(d) it changes with Earth's seasons

(e) Jupiter could have formed inside the snow line

22. Saturn to Sun distance is about 10 times larger than Earth to Sun distance, and the mass of Saturn is about 100 times greater than the mass of the Earth. The force of gravity between Sun and Saturn is ................. the force of gravity between Sun and Earth.

(a) 100 times larger than

(b) 10 times larger than

(d) 10 times smaller

(e) 100 times smaller.

23. What is the correct order of the inner planets from the Sun outward?

(a) Mercury, Venus, Mars, Earth

(b) Mercury, Venus, Earth, Mars

(d) Mercury, Mars, Venus, Earth

(e) Venus, Mercury, Mars, Earth

24. The inner (terrestrial) planets are rocky because

(a) the Sun's gravity drew primarily heavy elements into the inner part of the early Solar System

(b) the Sun converted all the Hydrogen and Helium in the inner Solar System into iron and nickel

(d) only rocky material was able to condense in the hot inner part of the early Solar Nebula

(e) the statement is misleading in that the inner planets are not appreciably more rocky than Jupiter or Saturn

25. The volcanic activity on Io is a consequence of

(a) tidal heating due to Jupiter

(b) decay of radioactive materials in the Io's interior

(d) frictional heating due to atmospheric winds

(e) interaction with Jupiter's rings

26. Plate tectonics

(a) is known to take place on all terrestrial planets

(b) can happen on a planet with no internal heat

(d) on Earth will presumably slow down in the future as the internal sources of energy get depleted

(e) is responsible for the greenhouse effect

27. X-ray telescopes have to be above Earth's atmosphere because

(a) that increases telescopes magnification

(b) that makes them closer to the distant stars

(d) X-ray telescopes placed on the ground have very poor resolution

(e) X-ray radiation is harmful to humans

28. The atmospheric pressure on Venus is about 10,000 times that on Mars. This large difference in pressure is partly due to

(a) Venus being more massive than Mars

(b) Venus's atmosphere being more dense than the atmosphere of Mars

(d) Venus's atmosphere being hotter than the atmosphere of Mars

(e) More than one of the above are true statements

29. Americium-241 is a radioactive substance with a half-life of 430 years.

(a) If I have 10 grams of Am-241 today, I will be left with 1 gram in 860 years.

(b) If I have 10 grams of Am-241 today, I will be left with 5 grams in 860 years.

(d) Am-241 emits energetic particles at very regular intervals.

(e) None of the above

30. According to our theory of solar system formation, why do all the planets orbit the Sun in the same direction and in nearly the same plane?

(a) the original solar nebula happened to be disk-shaped by chance

(b) any planets that once orbited in the opposite direction or a different plane were ejected from the solar system

(c) the laws of conservation of energy and conservation of angular momentum ensure that any rotating, collapsing cloud will end up as a spinning disk

(d) the Sun formed first, and as it grew in size it spread into a disk, rather like the way a ball of dough can be flattened into a pizza by spinning it

(e) luck explains it, as we would expect that most solar systems would not have all their planets orbiting in such a pattern

NAME __________________________________ LAB # _________________________

Astronomy 1001 - Midterm #1 - February 28th Dr. Liliya Williams - Spring 2005

II. Short Essay (10 pts each)

1. Explain what is meant by differentiation. How does this process contribute to the heating of a planet?

2. Draw a schematic of ocean tides during full Moon. Your sketch must include the Sun, the Moon, the Earth, and the tidal bulge(s) of the Earth's oceans.

3. Explain the Greenhouse effect. A simple sketch and a few sentences will suffice.