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munchkin1616 in astronomy

Help!!!

I'm working on a huge astronomy assignment and there are 5 questions I'm not positive on. The assignment's worth a lot so I thought I'd ask here and see if the answers I have match group consensus. I'm keeping my answers off so I don't skew anyone, but am hoping they match up and thus I know what I'm doing :P

Thanks tons for your help!!!


1. Two Martian astronomers, Marvin and Melvin, are located due north and south of each other on the Martian Solstice. Marvin is on the tropic and sees no shadows cast at noon, Melvin is 355 km north and sees a 6-degree shadow at noon. What is the circumference of Mars in kilometers?
a) 17750 km
b) 28800 km
c) 21300 km

Hint: this is essentially Eratosthenes' method for measuring the circumference of the Earth c. 200BC translated to Mars. Drawing a picture like the one in the notes might help.
(over)

2. Aliens abduct you and dump you on a small island somewhere on Earth. After a few days, you notice that the angle of the Sun's path at sunrise and sunset is always at an exact right angle (90-degrees) to the Horizon. Where are you?
a) an island at 45-degrees North latitude
b) an island on the Equator
c) an island above the Arctic circle
d) an island at 45-degrees South latitude

3. An Apollo astronaut in full Moonsuit has a mass of 120kg or about 264 pounds on Earth. The Moon's gravity is 1/6-th that of Earth's. While on the Moon, the astronaut's mass is _____ and his weight is _____.
a) 120 kg, 264 pounds
b) 20 kg, 264 pounds
c) 120 kg, 44 pounds
d) 20 kg, 44 pounds
4. How do you express the numbers 0.17 and 542 respectively using scientific notation?
a) 1.7×10−1 ; 5.42×102
b) 1.7×101 ; 5.42×10−2
c) 1.7×10−1 ; 5.42×10−2
d) 1.7×101 ; 5.42×102
5. 1000 Million Years could also be written as
a) 10 Gigayears
b) 1 Trillion years
c) 1 Gigayear
d) 10 Megayears
e) 1 Terayear


4. How do you express the numbers 0.17 and 542 respectively using scientific notation?
a) 1.7×10−1 ; 5.42×102
b) 1.7×101 ; 5.42×10−2
c) 1.7×10−1 ; 5.42×10−2
d) 1.7×101 ; 5.42×102
5. 1000 Million Years could also be written as
a) 10 Gigayears
b) 1 Trillion years
c) 1 Gigayear
d) 10 Megayears
e) 1 Terayear

5. 1000 Million Years could also be written as
a) 10 Gigayears
b) 1 Trillion years
c) 1 Gigayear
d) 10 Megayears
e) 1 Terayear


Again, thank you tons and tons... this is definitely not my subject and I'm really trying hard to do well in it.

Comments

Hmm, I'm not one for doing someones homework, so here's pointers in the right direction:

#1 is by far the hardest. The circumference of a circle is 360 degrees, and 6 degrees seems to be 355 km, so the whole 360 circle would be....

#2 has some tricky wording. 90 degrees to the horizon means that (I think) that the sun travels starts in the exact east, goes directly overhead, and then sets in the exact west. The rest is just logic.

#3.. Divide by 6, but remember weight changes in different gravities, but mass doesn't, it's the same in any gravity.

#4 http://en.wikipedia.org/wiki/Scientific_notation

#5 http://en.wikipedia.org/wiki/SI_prefix

As I said, I don't like doing others homework, but these should give enough clues to figure it out on your own.


thank you tons and tons... I was right on the last 4, but the first one is still a semi- guess :) (and we're allowed to work in groups and divide up the problems and share, so no worries about breaking rules)
Oh, now that brings back memories. I need to steal some Astronomy textbooks.
oh don't you worry, I have 8 more weeks of this class, so I'm sure I'll be begging for more assistance :P

url for question #1

It's a variation on the method used by Eratosthenes to estimate the radius of the earth in classical Greece.

http://spiff.rit.edu/classes/phys240/lectures/solar_sys/solar_sys.html

McF
Cosmos

August 2015

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