The forces of friction, which oppose displacement, also carry out work when a body is moving. The work of friction is converted into heat. The greater the force of friction, the more force must be exerted to move the body. Verify how friction affects the displacement of some blocks.

Here is a circuit with two resistors connected in series, a voltmeter and an ammeter.

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 ancient Greeks knew that the parabolic mirrors are paraboloids of revolution which have the property of concentrating the rays at the focus of the paraboloid.

Mechanical energy is what is produced by mechanical type forces, like elastic and gravitational forces.The following three pictures show situations involving mechanical energy.

The educational resource shows an interactive animation about the internal combustion engine: in real combustion engines, the energy is extracted from the combustion of some type of fuel, which has been injected into a cylinder, finely pulverised and mixed with oxygen. Then the combustible mixture is compressed and ignited to explode. That is why these engines are known as combustion engines.

Concept of absolute error

Concept of instrumental errors

Concept that gravity is caused by the matter

Concept of inductive method

The educational resource shows a visual about the difference between mass and weight: mass is not the same as weight, although in ordinary life both words are used with the same meaning.

Concept of International System of Units

Definition of hydrostatic pressure

The educational resource shows a visual about fixed stars: today we know that the sun is no more than a star which is near to us. Stars like the sun, which are large gaseous spheres are called fixed stars.

Concept of deductive method

The principle of conservation of energy states that energy is neither created nor destroyed, it is just transformed from some types of energy into others. The following visual will help you to understand what is meant by the principle of conservation of energy when a body falls.

Travel from the universe to the atom

Dimensional equation concept

Concept of wave amplitude

Longitudinal wave concept