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standard acceleration

The acceleration imparted by the earth’s gravitation to a body located on the earth’s surface: If you raise such a body up a bit and let it fall, it will accelerate 9.81 metres per second squared, in other words: in every second, its speed will increase by 9.81 metres per second.

Standard acceleration, abbreviated as g, is often used as a measure for accelerations. For instance, an acceleration of 2 g corresponds to 2·9.81=19.62 m/s².

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surface

Geometric space with two dimensions. Examples include the plane or the surface of a sphere.

speed

An object's average speed is the distance it moves during a given period of time, divided by the length of the time interval. If you make the time interval infinitely small, the result is the object's speed at one particular moment in time. The notion of speed can be applied to waves in different ways; for instance, for a simple wave, the phase speed is the speed at which any given wave crest or wave propagates through space. See also the more general entry velocity.

second

In the International System of units: the basic unit of time. Defined as a certain multiple of the oscillation period of electromagnetic radiation set free in a certain transition within the electron shell of atoms of the type Cesium-133.

acceleration

Every change of velocity with time is an acceleration.

This definition is slightly different from our everyday usage of the word. Ordinarily, we talk of an object accelerating when it becomes faster and faster. The physics definition covers two more situations. An object that decelerates, becomes slower, thus changes its velocity and, in the physics sense, undergoes a (negative) acceleration. Also, in physics, velocity is not the same as speed. A constant velocity implies not only constant speed, but also a constant direction of movement. Once the direction changes, so does the velocity - the change in velocity is associated with the change in the direction of movement. Thus, in the physics sense, even a car going around a curve of the road at constant speed undergoes acceleration.

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standard acceleration

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