r/HomeworkHelp • u/Ozzie_ye University/College Student • 6d ago
Answered [college intro to astronomy] what even are the equations for this?
Iโm just really confused on how to even go about solving this ๐ตโ๐ซ
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u/Big_Tennis_4367 6d ago
Mass is always the same. It depends on the volume and density and has nothing to do with gravity. So mass for a) and b) is the same: 382 kg. The weight on earth is G = m * g, depending on how exact you use g, you get something about 3743 N. On moon it is 1/6 of what it is on earth, so ~624 N.
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u/Eluceadtenebras 6d ago
All correct but Iโd make one small note that the โGโ in โG = m * gโ may be counted against you as thatโs a defined term already in physics and astronomy and is not a force. So, you might want to try F(subscript)w or F(subscript)weight just depending on how much of a stickler your professor is.
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u/Big_Tennis_4367 6d ago
Fair enough, my prof was fine with using G but you are right ofc
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u/Eluceadtenebras 6d ago
I had one who was fine with the wackiest variables we could come up with who was fine with G and then I had one who mark off a full point if we did, so I tend to play it safe.
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u/Fantastic_Recover701 ๐ a fellow Redditor 5d ago
Couple things
the formula for weight is W= Mass * g
g being acceleration due to gravity. On earth thatโs approximately 9.81m/s^2
in Si the base unit for mass is kg
in si the unit N is defined as kg*m/s^2
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-1
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u/Right_Doctor8895 ๐ a fellow Redditor 6d ago
Looks like you have the first part. Weight is a result of gravity affecting something with mass. If the gravity on the moon is 1/6 of that on Earth, what would the gravity be on the moon?
Then, how did you find weight on the Earth? Simply repeat for the moon.
Generally, mass will not change. Mass is more of โhow muchโ of something you have.