Conceptually I understand that mass is a measure of the amount of stuff present in an object, while weight is a measure of the force of gravity applied to that object. An object of a given mass will have a bigger weight on Earth than on the moon because Earth’s gravity is stronger. But… mass is determined by weighing an object on a scale. And there is a simple mathematical conversion between grams (mass) and pounds (weight), implying that they’re just different units for the same concept. So what gives? (Also this is a question that applies to so many fields, I had no idea which flair to apply.)
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Your mass is the same everywhere in the universe. On the moon your mass is, say, 75kg, on mars it’s 75kg, in microgravity it’s 75kg, on earth it’s 75kg, on the surface of a neutron star it’s 75kg.
This mass doesn’t change. The work needed to move that mass also doesn’t change. If you want to accelerate 1000kg on earth (~~parallel~~ *perpendicular* to gravity so it’s not helping you) that takes the same effort as accelerating it on the moon, on mars, in space, etc.
Once accelerated and moving at a constant velocity it has the same kinetic energy on earth, the moon, mars, etc.
Along the same lines – put a mass on a strong and spin it in a circle at a given speed. The centripetal force in the string is going to be the same on earth, mars, the moon, etc (well, almost as long as it’s going fast enough the forces from local gravity aren’t significant, or if it’s on a surface that supports its weight).
Your weight however is the force your body experiences due to gravity. On the moon your weight is less than on earth. Ditto on mars. Your weight is not directly tied to momentum, kinetic energy, acceleration, etc. It’s just your mass multiplied by local gravitational force – it affects how much work you need to do to move through gravity (Eg stand up) but it does not affect kinetic energy; momentum, acceleration, etc.
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