Recent content by vinirn

These videos were recorded at Angicos, a small town of Brazil. They are records of the same phenomenon. Can someone identify it? A tornado? A gustnado? A dust evil? https://www.youtube.com/watch?v=nwmngFGhGqQ https://www.youtube.com/watch?v=x_LQ0aevpZk...

Sorry, I should have written E=m_{rel}c^2, where m_{rel}= \frac{m}{\sqrt{1-v^2/c^2}} I could be wrong, but this may be converted to E^{2}=(pc)^{2}+(mc^{2})^{2}

The photon is massless, but it has the so-called relativistic mass, the m in the equation E=mc^{2} The photon must have relativistic mass because E=hf. It's this mass that form the moment p of the photon

We consider the weight of the entire column of water from the bottom to the surface, or only the water beneath the stone? (considering only the column occupied by the stone) The stone is now supporting the weight of the water above itself.

Yah, I understood :smile:. But how this downward force on the water is reflected in the measure of the balance?

I can see three forces: the tension exerted by the cord, the buoyancy and the weight of the stone. The buoyancy is smaler than the weight of the stone, resulting in a downward net force. But this net force has the same intensity of the cord's tension, right? I know that the net force resulting...

Homework Statement A beaker with water is in equilibrium with a certain weight in a balance. Then we tie a cord to a stone, and soak the stone in water, without touching the bottom. What will the balance read and why? http://dl.getdropbox.com/u/698994/ilustra%20forums/experiencia%20empuxo.png...

The pressure applied to the low side is larger than the high side pressure. Remember the hydrostatic pressure, for the case of fluids exposed to a gravitational force: On the low side, the value of h is larger.

These minor complications are what I was referring to.

I think this post is appropriate here, because it is a conceptual problem, and I am questioning the standard answer. From the halliday Quick quiz 7.2: A person lifts a heavy box of mass m a vertical distance h and then walks horizontally a distance d while holding the box, as shown in Figure...

In the Einstein's theory of general relativity, the gravitation is an attribute of curved spacetime instead of being due to a force propagated between bodies. But the quest for the famous graviton does not presume that gravitation is due to a force? Is the quantum gravity conflicting with the...

The most simple example of using eletromagnetic energy I can remenber now is the http://en.wikipedia.org/wiki/Crystal_radio" , an ancient radio receiver that needs no battery. Its power source comes from the eletromagnetics waves received from a long wire antenna, It was very popular in the...