Download PHY 115–003 - Oakton Community College

PHY 115–003
Oakton Community College
Fall 2010
Practice Test 1
Useful formulas:
Ellipses: e 
c
a
perihelion distance = a(1 – e)
Kepler’s Third Law, about Sun:
Constant acceleration:
w = mg
g
Gm E
RE 2
L = I
1
mv 2
2
Fg  
Gm1m2
r
PEgrav = mgh
I
m r
2
i i
K rot  12 I 2
L = mvr
i
100 cm = 1 m
The Sun: mS = 1.99 × 1030 kg
G = 6.673 × 10–11 Nm2/kg2
2
Kepler’s Third Law, general: p 2 
Conversion factors:
TK = TC + 273.15
p2 = a3 ; p = orbital period in years, a = distance in astronomic units
v = v0 + at
g = 9.80 m/s2
KE 
aphelion distance = a(1 + e)
4 2
a3
GM 1  M 2 
1 km = 1000 m
2 rad = 360°
The Earth: mE = 5.97 × 1024 kg
c = 3.0 × 108 m/s
 rad = 180°
RE = 6.38 × 106 m
1 ly = 9.46 × 1012 km
1 AU = 1.496 × 108 km
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PHY 115–003
Oakton Community College
Fall 2010
Practice Test 1
1) Pluto is 5.906 × 109 km from the Sun. How long does it take for light from the Sun to reach Pluto?
2) If a galaxy that is 10 light-years away is moving away from us with an average velocity of 0.2 m/s, then
a galaxy that is 20 light-years away would be moving a) how fast, relative to us? b) which direction relative
to us?
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PHY 115–003
Oakton Community College
Fall 2010
Practice Test 1
3) Miami has a latitude of 26°N. As viewed from Miami, what is the altitude of Polaris?
4) At a certain time of the year, the pointer stars in the Big Dipper lie directly to the left of Polaris, when
viewed from Chicago at 2 am. At the same time of year, at what time would the pointers stars of the Big
Dipper appear to be directly above Polaris, as viewed from Chicago?
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PHY 115–003
Oakton Community College
Fall 2010
Practice Test 1
5) There is a range of latitudes on Earth from which it is possible to observe the Sun as being directly
overhead, with an altitude of 90°. What is that range of latitudes?
6) When the moon is in its third quarter phase, at which of these times does the moon rise?
about sunrise
about noon
about sunset
about midnight
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PHY 115–003
Oakton Community College
Fall 2010
Practice Test 1
7) On the planet Moe, its star (sun) was directly overhead the city of Larry at solstice. At the same time, the
star’s altitude was 84° in the city of Curly, 650 kilometers directly south of Larry. What is the
circumference of Moe in kilometers?
8) Pluto’s distance from the sun is about 39.48 AU. How long does it take for Pluto to go around the Sun?
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PHY 115–003
Oakton Community College
Fall 2010
Practice Test 1
9) A ball is thrown vertically upward, so that its velocity is +9.8 m/s right when a stopwatch reads zero.
What is the velocity of the ball (direction and magnitude in m/s) when the stopwatch reads 3 s?
10) The Moon orbits the Earth with an average period of 27.3 days, with an average distance of
384,000 kilometers. Determine the combined mass of the Earth and Moon.
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