Somebody said they are different because of gravity.
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Mass is how much stuff is in a thing. Weight is how much gravity pulls on the thing because of all the stuff in it
Mass is the amount of matter in something. The more of it, the more force it takes to get it moving.
Weight is the force of gravity acting on an object.
If you change gravity (because you’re on the moon, perhaps), the same amount of matter (mass) will weigh more or less (like on the moon).
Weight is the mass of something times how fast it accelerates due to gravity.
Strictly, we measure mass in grams or slugs, and weight in Newtons or pounds. However, in our daily lives, gravity is pretty constant so we use grams for weight and pounds for mass without distinguishing between mass and weight.
“Mass” is how much of something you have.
“Weight” is how much something presses down on a surface. Weight is defined as mass x gravitation.
On earth, weight and mass can be used interchangeably since gravitation is 1. On the moon, gravitation is 0.17.
‘1 gram of lead’ is an amount of lead sufficient to weigh 1 gram on Earth. If you take 1 gram of lead to the Moon, 1 gram of lead (referring to the amount) would press down on the surface of the moon with the equivalent force that 0.17 grams would press down on Earth while still being 1 gram of lead. It is literally 1 gram of lead which weighs 0.17 grams.
Another way to describe it is based on how much acceleration something would have given a force applied. So given a stationary piece of lead with 1 gram of mass and absent any gravity, if you apply an instantaneous force of 1 gram at 1 kmh, and assuming 0 friction losses and 100% energy transfer, the piece of lead should accelerate to 1 kmh. (Think like a cue ball hitting a billiard ball, the billiard ball shooting off and cue ball stopping dead.)
At its most basic, mass is the one measurement of the two you asked about which exists. Weight is an effect of the mass when acceleration is applied, specifically how much energy is required to accelerate it. (Btw, a gravitational field is indistinguishable from acceleration.)
Simply said, mass is the sum of all the building blocks you’re made of. It’s a fixed number for solid objects like a rock, a glass or a car.
But for living creatures that eat, drink, sweat and breathe, this number changes from second to second.
Any two objects exert a gravitational force on eachother, and this is where the term weight comes in. The more mass either object has, the stronger the gravitational pull on the other, and vice versa. When one object has waaay more mass than the other, like you & the earth, the gravitational force is observed to be constant, always the same.
It is assumed for the sake of argument that the Earth has a mass that never changes (although it does, but not significantly).
How big that difference is between the two objects’ masses is what determines the weight of the lighter object. The moon has a smaller mass than the Earth, therefore your body is pulled less strongly toward it. When you jump on the Moon you will go up higher and fall more slowly. You weigh less on the moon than you do on Earth.
When there are no objects around you at all (as astronauts get to experience in space) you don’t feel any gravitational pull and so you feel weightless.
Throughout all of this your mass remains the same.
Your *mass* is how much stuff you’re made of. Doesn’t matter what planet you’re on because the amount of stuff in you is the amount of stuff in you, it’s the same anywhere. But note this is not about size – a bowling ball and a barrel full of hay might have the same mass, and because the stuff in a bowling ball is more dense it is smaller and because the stuff in a barrel full of hay is less dense it is larger, but both have the same mass.
Your *weight* is a how much the planet you’re on is pulling you towards it. This is combination of two things: where you are (gravity) and how much stuff you’re made of (mass). The more stuff you’re made of, the more there is for the planet to pull on. And obviously bigger planets pull harder. So a bowling ball and a feather will have different weights on the same planet because they are made up of a different amount of stuff. But a bowling ball will have different weights on different planets because each planet pulls on the bowling ball in different amounts.
Say you have two plastic balls each has a mass of 500 grams, one is on earth, and the other one is on the moon. Identical objects with identical mass. The one on earth would weigh 500 grams=.5 kg=1.1 lbs. The one on the mood would weigh 82.67 grams=.0827 kg=.182 lbs. Mass is the amount of matter of an object, in this case they are identical, but weight is affected by gravity, which there is less of on the moon.
In physics:
* Mass is basically how much matter something contains. (Its not exactly that but it is kinda like that.)
* Weight is the force of gravity on that mass. Technically measured in Newtons, (but you can measure it in ‘how much mass would you need to generate this force near the surface of the Earth’)
* The weight measurement on a scale is the force needed to hold up the object being measured.
In common, everyday language and scenarios, if you are near the surface of the Earth, and neither you nor the scales are accelerating, then those 3 things are essentially all the same, because they are designed to try to measure the same thing.
(If you happen to be not near the surface of the Earth, or and using scales that are accelearating, then these 3 concepts can become separate, and you probably need physics knowledge to be able to use them in any useful way.)
Mass is the quantity of matter in an object, it doesn’t change if nothing acts on it. Weight is how “heavy” the object is. It depends on the gravity.
If you go on the Moon, your mass won’t change because you’re still composed of the same matter, but your weight will be inferior because gravity is less important there.
Let’s say you could survive in space without a spacesuit. If you take a scale to the moon you’ll weigh less than you would on Earth even though mass never changed.
Someone explained it to me like this and it’s made sense to me. Weight is what you measure on a scale. If you go up to the space station and weigh yourself, it would read zero– you are weightless. If you propel yourself at 30 mph toward a wall inside the space station, you would still get hurt. That’s because you still have mass.
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