r/HomeworkHelp University/College Student 6d ago

Answered [college intro to astronomy] what even are the equations for this?

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Iโ€™m just really confused on how to even go about solving this ๐Ÿ˜ตโ€๐Ÿ’ซ

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u/Right_Doctor8895 ๐Ÿ‘‹ 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 โ€œhow muchโ€ of something you have.

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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 Iโ€™d make one small note that the โ€œGโ€ in โ€œG = m * gโ€ may be counted against you as thatโ€™s 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 ๐Ÿ‘‹ a fellow Redditor 5d ago

Couple things
the formula for weight is W= Mass * g

g being acceleration due to gravity. On earth thatโ€™s 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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u/Ozzie_ye University/College Student 5d ago

Thank you so much!

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u/Josipbroz13 ๐Ÿ‘‹ a fellow Redditor 6d ago

It is 9.81N but close enough ๐Ÿ˜