Mass Question. Converting weight into mass?

Your weight is the force of gravity on you.

According to Newton's universal law, the force of gravity between you and the earth is proportional to your mass and the earth's mass and inversely proportional to the square of the distance between you and the center of the earth.

F = G myou mearth / r^2 = mg

where g is the acceleration due to gravity:

g = G mearth / r^2 = 9.8 m/s^2 = 32 feet / s^2

In SI (the units you learn in physics 101), mass is given in kg and force (weight is a force) is in Newtons (kg m/s^2)

For everyday purposes, you can measure both mass and force in pounds (or kg in most of the world). So if you have your weight in pounds, that is also your mass in pounds. You don't have to multiply by anything.

The cost of using those units (and not having to multiply by g to convert weight and mass) is that you have to pick up that factor of g in Newton's 2nd law:

F = m (a/g)

So if you are pushed by a force that is N times your weight (or mass), you are accelerated at N*g.

Bill--the US aren't the only ones who use non-SI units. Go to a market in Europe and buy some fruit. You won't be weighing them in Newtons. And don't worry, noone uses poundals or slugs. Pounds are pounds. They aren't any worse than kg. If you're converting $ to euro (or loonies or whatever) in your head anyway, what's another conversion from pounds to kg.

gravity doesn't change just because you want to measure your weight in pounds instead of newtons or kg, it's still 9.8 m/s².

If your question is about gravity in US units, then it is:

g = 9.8 m/s² = 32.2 ft/s²

If you want to get into the very strange US units around mass and weight, no thanks, I use only SI units in that area, I refuse to learn pounds, poundals, slugs, pound-force, pound-mass, and all the rest.

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if you convert your weight from pounds to kilograms then gravity is ten

hope this helped (:

i'm only in year nine so it may not be the best answer :|

gravitys wicked. I love that a body with twice the mass will accelerate at half but will obviously have twice the weight so in turn cancel it out!!!!!!!!!!!!!!!!!!! Awsome