If at relativistic speeds bodies decrease in length, would it be possible to shut a large rocket which was travelling at the speed of light in a hangar? The answer to this question constitutes a "relativistic paradox".

Imagine that a wave passes from a deeper zone to another shallow zone, or vice versa. There will be refraction.

¿A cuántos radianes por segundo va la bola azul?

Angles can be measured with sexagesimal degrees. A right angle is equal to 90 degrees. Radians are another way of measuring angles.

The radioactive constant or decay constant, is a coefficient of proportionality which relates the atoms which disappear in a period of time t, with the initial atoms for each radioactive nuclide.

The activities of the isotopes formed at each stage of the radioactive series are equal to each other after some time. It is then said that radioactive equilibrium has been reached.

Radiation emitted by radioactive bodies.The radiation emitted by radioactive substances behaves differently when it passes through electric and magnetic fields.

The activity of a sample of a radioactive substance is the number of nuclei which disappear per unit of time and represents the speed of decay.

If we had particles between two barriers of potential, but of finite size, there could be diffraction on the other side of the barrier; this phenomenon is called the tunnelling effect.

We cannot give any value to the energy of the particle. Its wavelength must "fit" in the well, the same way the harmonics of the musical notes on a guitar must adjust to the length of their strings.

Electron in quantum atom (atomic orbitals).

Any body submerged in a fluid is subject to many small forces acting on each face. Force acting on the walls of a submerged object

Hydrostatic pressure varies with depth and the density of the liquid. In this visual and using a somewhat strange receptacle, you can verify this equation

Pressure Concept

Power measures the speed with which work is done. It is measured in watts, W, in the International System of Units. The following visual will help you to understand this concept more clearly as you see the work done by a jack to lift a car.

The speed with which work is done is called power. To lift the same object to the top implies carrying out the same amount of work. To lift it at a different speed, implies using a different amount of power.

The power switch is one of the elements of a consumer unit.

The educational resource shows a visual about the potential energy: two balls are on the point of falling, they possess gravitational potential energy. When they reach the snow they will modify their state. What will this depend on?

The atoms are usually neutral state. The agitation of a gas increases when it absorbs heat. If enough heat is absorbed, electrons are stripped from atoms and matter is ionized, saying that it is in plasma state.

Light behaves in two ways: like a particle and like a wave. The way a photoelectric cell works shows the corpuscular behaviour of light.