Weight what is it

In their Volume 1 second edition , they define weight in a way that puts them squarely in the mg Camp. In Section , they discuss the fact that the only force acting on an astronaut orbiting Earth in a spaceship is gravitational: mg , which they have previously defined to be his weight. But since we all know that astronauts float around inside their capsule, the authors add that "the astronaut experiences apparent weightlessness". Now they have painted themselves into a corner, and feel obliged to write "Paradoxically, the only time a body experiences apparent weightlessness is when the only force acting on it is its weight!

Clearly, the mg Camp's definition of weight has caused it to declare a paradox in this simple situation. In contrast, the Contact Camp has no problem with the astronaut. He is weightless, pure and simple. Another point worth pondering is how these two definitions of weight might dovetail with Einstein's theory of gravity.

Einstein's theory draws a quantitative comparison between the measurements of an observer inside an accelerating rocket far from gravity with those of a non-accelerating observer in a gravitational field.

The Contact Camp will say that both observers feel weight, and so this camp has no problems making the comparison required by Einstein. In contrast, the mg Camp will say that the rocket observer has no weight because there is no gravity in the rocket: g is zero , and that the observer in the gravity field does have weight because g is non zero there.

To insist that the experience of the rocket observer is "apparent" while that of the observer in the gravity field is real goes against the principle of relativity. Yes, the mg Camp will say that both observers have an apparent weight; but because they differentiate between apparent weight and mg , they have taken the focus away from what Einstein is really addressing: gravity, g. Here are two thought experiments to help you distinguish between the two definitions of weight—and to decide for yourself which camp you'd like to be in.

But remember, as Sheldon Cooper would say, there's only one right answer. Imagine some phenomenon occurred that made Earth spin gradually faster and faster. If you were positioned at the Equator, the gravity force on you would exactly provide the centripetal force that keeps you moving in a circle in the Solar System frame, so the ground would not push up on you.

You would be floating! Close to the Equator you would find yourself just settled on the ground, only marginally registering a non-zero reading on a set of weighing scales. The farther you moved from the Equator, the more you'd find yourself pinned to the ground. No one would deny that at the Equator you felt a complete lack of bodily sag, along with an amazing ability to float about. So would you describe your perception of a lack of weight at the Equator as real the Contact Camp or apparent the mg Camp?

What is so " apparently weightless" about floating like a levitating saint? And what is so " apparently increasing in weight" about finding yourself sag more and more the farther from the Equator that you move? We feel forces like this as weight. You would weigh less on the Moon because the gravitational field strength of the Moon is one-sixth of that of Earth 1.

But note that your mass would stay the same. On Earth, if you drop an object it accelerates towards the centre of the planet. The weight of an object is calculated using this equation:. A person has a mass of 60 kg. How much would the same person weigh on the Moon, if the gravitational field strength is 1. A lot of people ring in the New Year with vows to lose weight and exercise.

Yet we keep doing the cleanses, buying the meal replacement bars, and joining Weight Watchers. The problem, says UC Davis physiologist and nutritionist Linda Bacon, is that very few people can lose weight and keep it off. Then the commercial weight loss behemoths Weight Watchers and Jenny Craig joined this crowded field. The rule of law, you see, buckles, bends and sometimes crumbles under the weight of racism, sexism, and classism. Of course, considerations of weight have to be taken into account, but the more mould round the roots the better.

Results are in terms of bulk of precipitate, which must not be confused with percentage by weight. The weight percentage can be found by referring to Purdy's tables, given later. But for the most part even industry and endowment were powerless against the inertia of custom and the dead- weight of environment. All the eight planets added together only make one-seven-hundredth part of his weight.

The force exerted on any object by gravity. New Word List Word List. Save This Word! See synonyms for weight on Thesaurus. We could talk until we're blue in the face about this quiz on words for the color "blue," but we think you should take the quiz and find out if you're a whiz at these colorful terms.