Are g or kg ever a proper unit for weight? A = YES

Thank you all for your comments. Knowing now that there actually is a legitimate unit kilograms-force, I must concede that my assessment that something "wrong" was being taught. I am completely comfortable with the teaching of partial concepts.

I didn't learn about pound-mass and pound-force until highschool physics. We were also taught about kg and N (Newtons) as corresponding SI units for mass and weight. I just never knew that kilograms-force was another unit. The saying is true, you learn something new every day. I basically saw people using kg and g everywhere to describe weights here on earth, and I thought it was just a convention since most of our needs to describe weights are limited to here on Earth.

It never would have struck me as odd at all if they hadn't started talking about weight in kg on the Moon and Jupiter.


So, to stimulate the English and Gramar experts on PC and to change the subject a little, here is another observation from the Glencoe/McGraw Hill worksheet that caught my attention as a possible error:

I adjusted the two quoted questions in the original post to be correct to my own knowlege. Originally, they apeared like this. See if anything looks gramatically incorrect to you. Then read on to see what I thought, and tell me if I am crazy.

6. On earth, an astronaut weighs 60 Kg. How much will she weigh on the moon?
7. The gravity on Jupiter is 2 – ½ times that of earth. How much would the 60 Kg astronaut weigh if she could land on Jupiter?


OK, here the beef. Is Jupiter somehow more important than Earth or the Moon? Shouldn't Earth and Moon be capitalized when referring to specific celestial bodies? If talking about dirt, you can use earth in all lower case, and if talking about the general classification of moon, such as Jupiter has 12 moons, lower case is OK, but if talking about the Moon, specifically the Earth's moon, then Moon must be capitalized. Am I correct?

Please don't comment on any of my spelling, because though I am an engineer, I cannot figure out how to use PC's spell checking feature.

 

Thank you all for your comments. Knowing now that there actually is a legitimate unit kilograms-force, I must concede that my assessment that something "wrong" was being taught. I am completely comfortable with the teaching of partial concepts.

I didn't learn about pound-mass and pound-force until highschool physics. We were also taught about kg and N (Newtons) as corresponding SI units for mass and weight. I just never knew that kilograms-force was another unit. The saying is true, you learn something new every day. I basically saw people using kg and g everywhere to describe weights here on earth, and I thought it was just a convention since most of our needs to describe weights are limited to here on Earth.

It never would have struck me as odd at all if they hadn't started talking about weight in kg on the Moon and Jupiter.


So, to stimulate the English and Gramar experts on PC and to change the subject a little, here is another observation from the Glencoe/McGraw Hill worksheet that caught my attention as a possible error:

I adjusted the two quoted questions in the original post to be correct to my own knowlege. Originally, they apeared like this. See if anything looks gramatically incorrect to you. Then read on to see what I thought, and tell me if I am crazy.

6. On earth, an astronaut weighs 60 Kg. How much will she weigh on the moon?
7. The gravity on Jupiter is 2 – ½ times that of earth. How much would the 60 Kg astronaut weigh if she could land on Jupiter?


OK, here the beef. Is Jupiter somehow more important than Earth or the Moon? Shouldn't Earth and Moon be capitalized when referring to specific celestial bodies? If talking about dirt, you can use earth in all lower case, and if talking about the general classification of moon, such as Jupiter has 12 moons, lower case is OK, but if talking about the Moon, specifically the Earth's moon, then Moon must be capitalized. Am I correct?

Please don't comment on any of my spelling, because though I am an engineer, I cannot figure out how to use PC's spell checking feature.

 

<div class='quotetop'>QUOTE(Alric @ Sep 13 2007, 10:11 AM) [snapback]511952[/snapback]</div>

That would be a real Dirty Trick, as those answers are what astronaut's mass would be and they are asking for weight. But I have seen trick questions before where the trick was that off the wall.

Funny, it took me a while to figure out what you were saying because I saw your answers as "6.60 kg" and "7.60 kg, so at first I posted "What trick gave you those answers?" Then I figured out they were numbered 6. and 7. so I came back here to edit.

I coached my daughter to answer as follows:
Q6 A = On the Moon, 60 kg astronaut would weigh 98.1 N (60 kg)*(9.81m/s^2/kg)*(1/6 Moon/Earrh)
Q7 A = On Jupiter, 60 kg astronaut would weigh 1472 N (60 kg)*(9.81m/s^2/kg)*(2.5 Jupiter/Earth)

It was actually only a trick question if you are beyond the lesson enough to ask is it 60 kg-mass or 60 kg-force. The question assumes you only are aware of kg-force or you sssume they are using kg-force.

The answers they wanted with all kg in kg-force are:
Q6 A = On the Moon, 60 kg astronaut would weigh 10 kg (60 kg)*(1/6 Moon/Earrh)
Q7 A = On Jupiter, 60 kg astronaut would weigh 150 kg (60 kg)*(2.5 Jupiter/Earth)

So, unfortunately, I frustrated the teachers efforts by being too far ahead of the lesson and confused my daughter. The teacher told her I was right, but beyond what they were learning right now, which is a fair resolution.


Another set of question that bugged me, and probably shouldn't have were these, paraphrased from my memory, made up the Q numbers and numbers part:

A setellite weighs 2000 kg on Earth.
Q8. How much mass would it have while orbiting the Earth?
A expected = 2000 kg

Q9. How much would the satellite weigh while orbiting the Earth?
A expected = 0 kg.
But being cursed as an engineer, I coached my daughter to enter:
A by engineer = "Very little, but it is the satellite's small amount of weight from the Earth's gravity acting on it that keeps it in orbit around the Earth."

I think that my wife should help my daughter with homework from now on.

 

<div class='quotetop'>QUOTE(Alric @ Sep 13 2007, 10:11 AM) [snapback]511952[/snapback]</div>

That would be a real Dirty Trick, as those answers are what astronaut's mass would be and they are asking for weight. But I have seen trick questions before where the trick was that off the wall.

Funny, it took me a while to figure out what you were saying because I saw your answers as "6.60 kg" and "7.60 kg, so at first I posted "What trick gave you those answers?" Then I figured out they were numbered 6. and 7. so I came back here to edit.

I coached my daughter to answer as follows:
Q6 A = On the Moon, 60 kg astronaut would weigh 98.1 N (60 kg)*(9.81m/s^2/kg)*(1/6 Moon/Earrh)
Q7 A = On Jupiter, 60 kg astronaut would weigh 1472 N (60 kg)*(9.81m/s^2/kg)*(2.5 Jupiter/Earth)

It was actually only a trick question if you are beyond the lesson enough to ask is it 60 kg-mass or 60 kg-force. The question assumes you only are aware of kg-force or you sssume they are using kg-force.

The answers they wanted with all kg in kg-force are:
Q6 A = On the Moon, 60 kg astronaut would weigh 10 kg (60 kg)*(1/6 Moon/Earrh)
Q7 A = On Jupiter, 60 kg astronaut would weigh 150 kg (60 kg)*(2.5 Jupiter/Earth)

So, unfortunately, I frustrated the teachers efforts by being too far ahead of the lesson and confused my daughter. The teacher told her I was right, but beyond what they were learning right now, which is a fair resolution.


Another set of question that bugged me, and probably shouldn't have were these, paraphrased from my memory, made up the Q numbers and numbers part:

A setellite weighs 2000 kg on Earth.
Q8. How much mass would it have while orbiting the Earth?
A expected = 2000 kg

Q9. How much would the satellite weigh while orbiting the Earth?
A expected = 0 kg.
But being cursed as an engineer, I coached my daughter to enter:
A by engineer = "Very little, but it is the satellite's small amount of weight from the Earth's gravity acting on it that keeps it in orbit around the Earth."

I think that my wife should help my daughter with homework from now on.

 

<div class='quotetop'>QUOTE(dogfriend @ Sep 13 2007, 10:43 AM) [snapback]511970[/snapback]</div>

Shhhh, don't type that so LOUD! I am at work too.
Edit PS, when you say "Jupiter is the name of a God, so it is capitalized (I think thats why)",
you should not be capitalizing god as you are not using god as a Proper noun in this case.

And I still think Earth should be a proper noun because it is the name of a person, place or thing.
Remember Gramar Rock on Saturday mornings?

Oh, and I think I have said before, your dog has the best dog smile I have ever seen.

 

<div class='quotetop'>QUOTE(dogfriend @ Sep 13 2007, 10:43 AM) [snapback]511970[/snapback]</div>

Shhhh, don't type that so LOUD! I am at work too.
Edit PS, when you say "Jupiter is the name of a God, so it is capitalized (I think thats why)",
you should not be capitalizing god as you are not using god as a Proper noun in this case.

And I still think Earth should be a proper noun because it is the name of a person, place or thing.
Remember Gramar Rock on Saturday mornings?

Oh, and I think I have said before, your dog has the best dog smile I have ever seen.