ASTM 101 Unit 1 Homework 3
Multiple choice: select the best response for questions 1 through 3:
1) __a__ Newton discovered:
a. Gravity.
b. gravity is universal.
c. the planet Neptune.
2) __a__ The gravitational attraction between 2 objects is 120 N when they are 2 meters apart. What is
the gravitational attraction if they are moved to 1 meter apart?
a. increases to 480 N
b. increases to 240 N c. the same, 120 N d. decreases to 60 N e.
decreases to 30 N
The gravitational attraction between two objects is inversely proportional to the square of the distance between
their centers. Thus, if the distance is halved from 2 meters to 1 meter, the gravitational attraction will increase
by a factor of (2/1)^2 = 4. Therefore, the gravitational attraction will increase from 120 N to 480 N.
3) __e__ The gravitational attraction between 2 objects is 120 N when they are 2 meters apart. What is
the gravitational attraction if they are moved to 4 meters apart?
a. Increases to 480 N
b. increases to 240 N c. the same, 120 N d. decreases to 60 N e.
decreases to 30 N
Using the same reasoning as in the previous question, if the distance is doubled from 2 meters to 4 meters, the
gravitational attraction will decrease by a factor of (2/4)^2 = 1/4. Therefore, the gravitational attraction will
decrease from 120 N to 30 N.
MATCHING : for questions 4 through 11 select the best match from the list items a through j A
4) __e__ Newton’s 3rd Law
5) __g__ Kepler’s 3rd Law
6) __h__ Newton’s 2nd law
7) __d__ Kepler’ 2nd law
8) __j__ Newton’s 1st law
9) __a__ Kepler’s 1st law
10) __c__ Newton’s law of universal gravitation
11) __b__ Copernicus model
a. elliptical orbits
b. uniform elliptical motion
c. obeys inverse square law
d. equal areas in equal time
e.equal and opposite reaction force
f. uniform circular motion
g. time2 = distance3
h. force causes acceleration
j. objects at rest remain at rest
12) Define
a. Copernicus universe: A model of the solar system in which the Sun is at the center, and the
planets orbit in circular orbits around it.
b. Tycho universe: A model of the solar system in which the Earth is at the center, and the Moon,
Sun, and other planets orbit around it.
c. Mass: A measure of the amount of matter in an object.
d. Weight: The force exerted on an object due to gravity.
e. Force: A push or pull on an object that can cause it to accelerate or deform.
f. Density: The amount of mass per unit volume of a substance.
g. Aphelion: The point in a planet's orbit when it is farthest from the Sun.
h. Perihelion: The point in a planet's orbit when it is closest to the Sun.
i. Solstice: The time of the year when the Sun is at its highest or lowest point in the sky, marking
the longest or shortest day of the year.
j.
Equinox: The time of the year when the Sun is directly over the Earth's equator, marking the
beginning of spring or autumn.
k. Solar day: The time it takes for the Sun to return to the same position in the sky, as measured by
a sundial.
l. Sidereal day: The time it takes for the Earth to complete one rotation relative to the fixed stars.
m. Synodic month: The time it takes for the Moon to return to the same phase (e.g., full moon to full
moon).
n. Sidereal month: Sidereal month: The time it takes for the Moon to return to the same position
relative to the fixed stars.
o. Lunar eclipse: An event that occurs when the Earth passes between the Sun and the Moon,
causing the Moon to move into the Earth's shadow.
p. solar eclipse: An event that occurs when the Moon passes between the Sun and the Earth,
blocking the Sun's light and casting a shadow on the Earth.
q. position of Polaris as viewed in London [longitude: 7 oW latitude: 510 N ]:
Polaris, also known as the North Star, is located very close to the North Celestial Pole. As such,
it appears to be directly overhead (at an altitude of about 51°) to an observer located at a latitude
of 51°N, such as in London. Its azimuth (direction) is due north (0°).
r. Tycho model: A model of the solar system in which the planets orbit around the Sun, and the
Sun in turn orbits around the Earth.
s. Copernicus model: A model of the solar system in which the Sun is at the center, and the planets
orbit in circular orbits around it.
t. Ptolemy model: A geocentric model of the solar system, in which the planets move in epicycles
around the Earth.
u. RA: (Right Ascension) A coordinate used in astronomy to specify the east-west position of a
celestial object in the sky, measured in hours, minutes, and seconds.
v. DEC: (Declination) A coordinate used in astronomy to specify the north-south position of a
celestial object in the sky, measured in degrees.
w. ALT: (Altitude) The angle between a celestial object and the observer's horizon, measured in
degrees.
x. AZ: (Azimuth) The angle between the observer's northward-pointing horizon and the direction to
the celestial object, measured clockwise in degrees from due north.
y. Neap: A type of tide that occurs when the gravitational forces of the Sun and Moon are partially
canceling each other out, resulting in a smaller difference between high and low tide.
z.
Spring tide: Unusually high and low tides that occur twice a month during the full moon and
new moon phases. During these phases, the gravitational forces of the moon and sun are aligned
and reinforce each other, causing a greater difference between high and low tides.
13) How did Galileo’s telescope observations contradict the geocentric model?
Galileo's telescope observations contradicted the geocentric model in several ways. For example, he observed
that the Moon has mountains and valleys, which implied that the Moon is a solid object and not a perfect,
crystalline sphere as believed in the geocentric model. He also observed that Jupiter has four large moons
orbiting around it, which contradicted the idea that all celestial objects orbit around the Earth.
14) What is a barycenter?
A barycenter is the center of mass of two or more celestial bodies that are orbiting around each other. In other
words, it is the point in space where the combined gravitational forces of the two objects balance each other out,
causing them to orbit around that point rather than one another.
15) What are Tycho’s greatest contributions?
Tycho Brahe's greatest contributions include his accurate and comprehensive observations of the positions of
the planets and stars, which helped improve the accuracy of the geocentric model. He also introduced new
observational techniques, such as the use of large, precision-made instruments and the compilation of star
catalogs, that revolutionized the field of astronomy.
16) Why is it cold in the winter in the Northern hemisphere.
It is cold in the winter in the Northern Hemisphere because during that time, the Earth's axis is tilted away from
the Sun. This means that the sunlight is spread over a larger area and the angle of incidence is lower, resulting
in less solar heating. Additionally, the days are shorter in the winter, which means there is less time for the Sun
to heat up the Earth.
17) What is the orbital period of a planet that is orbiting 8 AU from the Sun?
The orbital period of a planet that is orbiting 8 AU from the Sun can be determined using Kepler's third law,
which states that the square of the orbital period is proportional to the cube of the semi-major axis of the orbit.
Plugging in the values, we get:
(T/1 year)^2 = (a/1 AU)^3
T^2 = a^3
T = sqrt(a^3) = sqrt(8^3) = 17.89 years
Therefore, the orbital period of the planet is approximately 17.89 years.
18) Rank these distances from largest to smallest.
A: Astronomical unit,
B: kilometer,
___C___
___E___
___A___
C: lightyear
D: meter
___B___
___D___
E: parsec
Or indicate they are all equivalent distance using = signs
19) What constellations are visible along the ecliptic?
The constellations that are visible along the ecliptic are the twelve zodiac constellations; Aries, Taurus, Gemini,
Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, and Pisces.
20) Describe the motion of stars if you are an observer at the north pole.
If you are an observer at the North Pole, the stars appear to rotate counterclockwise around the celestial pole.
All the stars would be circumpolar, which means they would never rise or set. The entire sky would appear to
rotate around a single point in the sky, which is the north celestial pole.
21) Describe the motion of stars if you are an observer at the equator.
If you are an observer at the equator, the stars appear to rise in the east and set in the west, just like the Sun. The
celestial equator passes directly overhead, and the stars appear to move in a straight line across the sky. The
stars near the north and south celestial poles would appear to move close to the horizon, and the entire sky
would appear to rotate around an axis perpendicular to the horizon.
22) Label the phases of the Moon shown as images A,B,C,D
A. Waxing Gibbous
B. Waning Crescent
C. First Quarter
D. Third Quarter
23) Starting with a new moon, list the phases A,B,C,D in order that they would appear
A. First Quarter. B. Waxing Gibbous.
C. Third Quarter.
D. Third Quarter