Is my teacher mistaken?

[Google90]

Today in physics class we were doing acceleration on objects and all that cool stuff. Later in class, she says

 

 

 

 

 

"The Newton is the SI unit for weight. It is not the kilogram, its a common misconception...you don't say 'I weigh 150 KG, you say, I weigh 150 Newtons'....so on to the problem...if a Rocket Weighing 9800 Newtons lifts of with an accele--...bla blah......"

 

 

 

 

 

 

 

So I'm a refugee from Europe now living in the U.S...

 

 

 

Point is, I've lived for 10 years of my life In Europe. I have NEVER heard someone say "Oh...I weight 80 Newtons, how about you?" in Europe.

 

 

 

She has completely confused me for our upcoming test now...

[Rebdragon]

This is, uh, one of the massive basics of Physics.

 

 

 

Your teacher is not mistaken.

 

 

 

Yes, it sounds weird, but weight is a force. You'll get over it in a week.

[Google90]

I know it's a force...but it just sounds so stupid to me..."I weigh 60 newtons"

[indy500fan]

Kilogram is a measurement of mass. A Newton is a measurement of force. Weight is a measurement of force, but saying your mass as weight is normal also.

 

 

 

In most modern scientific work, physical quantities are measured in SI units. The SI unit of mass (and hence weight in some everyday senses)[3] is the kilogram. The SI unit of force (and hence weight in the mechanics sense) is the newton (N)

[Evil_Sabre]

I know it's a force...but it just sounds so stupid to me..."I weigh 60 newtons"

 

 

 

of course no one says that in everyday life, your in a physics class, many of your calculations will be based around the newton so it makes things much easier

[mrpez]

No its true. In physics mass is attributed to the kilogram, but objects can be weighed in Newtons (N) also.

[Nom]

Well, nobody says "It's 273 degrees Kelvin outside!" in Europe either. . .

[Google90]

No its true. In physics mass is attributed to the kilogram, but objects can be weighed in Newtons (N) also.

 

 

 

So Newton= Kilogram?

 

 

 

So...

 

 

 

1 Kilogram= 2.2 Pounds?

 

1 Newton= 2.2 Pounds?

[la la la]

Force = mass * acceleration, and downward force=weight.

 

Acceleration due to gravity is 9.8 m/sec^2, and so someone who is 100 kilograms would actually weigh 980 newtons.

 

That would make 1kg=9.8nt

 

 

 

Another common misconception is people thinking that pounds (lbs) measures mass. Pounds measures weight!! The actual American measurement for mass is a slug, which is 32 pounds (due to gravity's acceleration being 32 ft/sec^2).

 

 

 

Well, theres my little physics for the day.

[misterxman]

Your weight in newtons is your mass times 9.8 (m/s^2).

 

 

 

Your weight in kilograms is just your mass.

 

 

 

Each gives a different number, but weight in newtons just tells you how much force gravity is applying on you (which changes with acceleration).

 

 

 

Your weight in newtons changes when you stand on different planets because the gravitational acceleration changes. Your weight in mass stays the same on any planet because your mass (quantity of matter) doesn't change anywhere.

[Google90]

Thanks for the clarification guys...I swore she was an Idiot. ( She is a really bad teacher though)

[malo2]

Kilogram is a measurement of mass. A Newton is a measurement of force. Weight is a measurement of force, but saying your mass as weight is normal also.

 

 

 

In most modern scientific work, physical quantities are measured in SI units. The SI unit of mass (and hence weight in some everyday senses)[3] is the kilogram. The SI unit of force (and hence weight in the mechanics sense) is the newton (N)

makes absolutely no sense, If it were a measure of mass then simple scales wouldn't work, you would need to measure the weight on a scale, then divided it by the volume to get the mass. I don't remember anybody doing that to measure something in kilograms.

 

 

 

or is it just that normal electronic scales would be void on the moon?

[indy500fan]

makes absolutely no sense, If it were a measure of mass then simple scales wouldn't work, you would need to measure the weight on a scale, then divided it by the volume to get the mass. I don't remember anybody doing that to measure something in kilograms.

 

 

 

or is it just that normal electronic scales would be void on the moon?

 

 

 

Divide by volume? What the hell are you talking about?

[malo2]

makes absolutely no sense, If it were a measure of mass then simple scales wouldn't work, you would need to measure the weight on a scale, then divided it by the volume to get the mass. I don't remember anybody doing that to measure something in kilograms.

 

 

 

or is it just that normal electronic scales would be void on the moon?

 

 

 

Divide by volume? What the hell are you talking about?

have you not been taught about mass in school?

[ortiz9471]

makes absolutely no sense, If it were a measure of mass then simple scales wouldn't work, you would need to measure the weight on a scale, then divided it by the volume to get the mass. I don't remember anybody doing that to measure something in kilograms.

 

 

 

or is it just that normal electronic scales would be void on the moon?

 

 

 

Divide by volume? What the hell are you talking about?

have you not been taught about mass in school?

 

 

 

You don't need volume for a scale to work.. When was the last time you saw a scale somehow measure your volume?

 

The scale measures the acceleration due to gravity pulling down on your body, giving you your weight. It then changes it into kilograms by dividing it by 9.81

 

 

 

It's not that hard of a concept

[malo2]

makes absolutely no sense, If it were a measure of mass then simple scales wouldn't work, you would need to measure the weight on a scale, then divided it by the volume to get the mass. I don't remember anybody doing that to measure something in kilograms.

 

 

 

or is it just that normal electronic scales would be void on the moon?

 

 

 

Divide by volume? What the hell are you talking about?

have you not been taught about mass in school?

 

 

 

You don't need volume for a scale to work.. When was the last time you saw a scale somehow measure your volume?

 

The scale measures the acceleration due to gravity pulling down on your body, giving you your weight. It then changes it into kilograms by dividing it by 9.81

 

 

 

It's not that hard of a concept

if you read the originally quoted post you would realize that was exactly my point.

[Rebdragon]

Divide by volume? What the hell are you talking about?

have you not been taught about mass in school?

 

Seriously, what the hell are you talking about?

[indy500fan]

if you read the originally quoted post you would realize that was exactly my point.

 

 

 

I still have no idea what you are talking about.

[malo2]

apparently nobody on this thread knows that mass=weight/volume, something that should have been taught in 6th grade :-k

[indy500fan]

apparently nobody on this thread knows that mass=weight/volume, something that should have been taught in 6th grade :-k

 

 

 

LOL! EPIC FAIL.

 

 

 

I see the problem in communication here, you are an idiot.

[misterxman]

mass = volume x density

 

 

 

mass = weight force / gravitational acceleration

 

 

 

Two different formulas which are being confused.

[ktmcf121]

mass = volume x density

 

 

 

mass = weight force / gravitational acceleration

 

 

 

Two different formulas which are being confused.

 

 

 

there ya go. also, whoever said kilogram = newton was totally wrong.

 

 

 

a newton is defined as a kilogram meter per second squared, or kg*m/s^2

 

mass = kg

 

acceleration = m/s^2

 

 

 

therefore f = ma (N = kgm/s^2)

 

 

 

"weight" is just a special unit of force which takes gravitational acceleration into account.

[Kill_Thomas9]

NEWTON = WEIGHT

 

KILOGRAM = MASS

 

 

 

 

 

---------------------------

 

 

 

 

 

 

 

mass = volume x density

 

 

 

mass = weight force / gravitational acceleration

 

 

 

Two different formulas which are being confused.

 

 

 

there ya go. also, whoever said kilogram = newton was totally wrong.

 

 

 

a newton is defined as a kilogram meter per second squared, or kg*m/s^2

 

mass = kg

 

acceleration = m/s^2

 

 

 

therefore f = ma (N = kgm/s^2)

 

 

 

"weight" is just a special unit of force which takes gravitational acceleration into account.

 

 

 

Thats exactly what I learned the first day of highschool in physics. A Newton is just a simplified way of writing an object's mass * gravity. Without the Newton, we would have to multiply m*g multiple times every time we wanted to write an equation.

[Rebdragon]

NEWTON = WEIGHT

 

KILOGRAM = MASS

 

 

 

Thats exactly what I learned the first day of highschool in physics. A Newton is just a simplified way of writing an object's mass * gravity. Without the Newton, we would have to multiply m*g multiple times every time we wanted to write an equation.

 

Mass * g [acceleration due to gravity] is only one of an infinite uses for the Newton. The Newton is simply a measure of force- because weight is a force, it is measured in Newtons. The Newton is not simply so some people can get away with not writing m*g :P .

[ktmcf121]

just be glad you don't have to use the english system. we have 2 units of mass, the "lbm" and "slug"

 

 

 

lbm, or pound-mass. is the same thing as a pound-force. so one pound-force equals one pound-mass(on earth anyways), or 1/32 slugs. (assuming 32 feet per second squared for gravitational acceleration)

 

 

 

#-o