When an undulatory movement comes across an obstacle which prevents its propagation and does not absorb its energy, the waves change direction, they are reflected.

Forces are represented by means of vectors. A vector is an oriented sector. The following animation representes the characteristics of a vector.

El principio de relatividad de Galileo enuncia que desde cualquier sistema de referencia inercial se observan las mismas leyes físicas (desde todos ellos se miden las mismas fuerzas) .

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.

Un rayo de luz atraviesa un medio, una parte se refleja y otra se refracta

Cuando un rayo de luz atraviesa una lámina de vidrio, se refracta. En determinadas circunstancias puede producirse una reflexión total

¿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.

Una de las formas de expresar los ángulos son los grados sexagesimales. Un ángulo recto tiene 90 grados sexagesimales. Otra manera de expresar la magnitud de un ángulo son los radianes.

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.

Se produce a partir un isótopo que se ha obtenido previamente en el laboratorio mediante una reacción nuclear. Este isótopo sigue todas las leyes radiactivas que rigen la radiactividad natural.

Las "partículas" gamma son radiaciones electromagnéticas, ondas, que acompañan a la emisión de partículas alfa o beta.

La radiactividad es la propiedad que tienen ciertas sustancias de emitir radiaciones

El rozamiento entre dos superficies tiene su origen en la rugosidad que poseen, incluso a nivel molecular. La siguiente animación te permitirá ver qué ocurre cuando un objeto se desplaza sobre otro.

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.