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Hi! Thanks for answering my questions.

Lets say two weights are on a board, and their weight is balanced by a log, under the board at the center between the weights. Naturally, if one side of the board is unbalanced it will slowly fall to the ground, making the other weight rise up higher into the air, what are some ways that someone could do that same experiment "wirelessly", in other words, without the board but simply having that energy exchange between the weights be "wireless"?

Question Date: 2007-10-21
Answer 1:

Lets think about how the log and weight system works first.

The weights exert a force straight down on the log, but in different locations. At the same time the log is resting on a pivot point, which is holding the log up and keeping the balanced weights off the ground. This pivot is also exerting a force on the log at a different location and direction.

So, we have 3 forces on the log and all of these forces add to zero if the system is balanced. You could say that the two weights are communicating with one another 'through' the log, because they both are connected to the log. There is no energy exchange between the weights when the system is balanced.

I cannot think of a way to do this wirelessly. The system really just relies on a balance of forces on the log. Wireless communications (through radio waves) can be used to transmit information but not a force, in the sense of this experiment. I hope this helps! I also found a fun site where you can put different weights on the 'log' and release the log to see what happens.


Answer 2:

This is an excellent question, because most of us weigh things on a daily basis.Usually, when one thinks of weighing an object, they immediately think of a medium to measure weight such as a balance or scale. But what happens when you don't have a scale? How else could you measure and compare the weights of two objects?

Well, one way is to take advantage of the gravitational forces on Earth. For example, you could simultaneously drop two objects from the balcony of a two story building. The object that falls faster and hits the ground first would be the heavier one.

You brought up energy in your question, and it is a good idea. Technically, lifting a weight into the air requires energy, since you are moving a force a certain distance. A transfer of energy is called work which is equal to force times distance. An object sitting on a desk has no energy, but when you lift that object up, you acquired energy. On a balance, a transfer of energy occurs between two objects of unequal weight. The heavier weight will sink (potential energy) causing the lighter object to lift (kinetic energy), essentially transferring potential energy to kinetic energy. So in a sense, you can compare two objects by means of energy rather than force (weight).

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