# Time in Physics

We explain to you what time is approached since Physics and its formulas. Time in classical mechanics and relativistic mechanics.

### What is the time in physics?

In physics, time is called a magnitude that **serves to measure the duration or the separation of one or more events** . This allows them to be sorted in a sequence (past, present, future) and determine whether or not they occur simultaneously.

Time **is represented by the variable t**, its unit of measurement in the International System is the second (

*s*), in a sexagesimal framework (60 units constitute a larger one) and the device with which it is measured is the clock .

Time can be thought of as the duration of things that are subject to change, and it **is one of the most important physical quantities** . Within the physical considerations, it is considered a variable that, combined with others, allows to determine the position, movement, speed and many other magnitudes of an object or system.

More in: Time.

### Formulas to calculate the time

Time is involved in numerous physical calculations, therefore there will be many possible formulas to calculate it, depending on the other variables we have at hand. To cite some examples:

**Speed**The speed is calculated from the formula V = dt (Speed is equal to distance by time). It is measured in units of distance per units of time: Km / h, m / s, etc. If we clear the time in this formula, it would be that t = d / v.**Acceleration**The acceleration (*a*) is the change in time between two speeds and is calculated with the formula: a = Δv / Δt, where Δv is_{initial}v -_{final}v and Δt is_{initial}t -_{final}t, that is, clearing, that : t = (V_{f}- V_{i}) / 2a.**Time dilation**. The formula for calculating, in quantum mechanics, the time dilation of an event measured at rest with respect to itself is determined with the following formula: Δt '= Δt_{i}/ √1-v^{2}/ c^{2}.

### The weather in classical mechanics

In classical physics, time **is considered an absolute value**, which occurs the same for all the phenomena studied. This means that two different observers will always agree on the order of events (past, future and present simultaneously).

### The time in relativistic mechanics

In the relativistic mechanics of physics, time is a more complex concept, since **it is linked to the position of the observer of the event**, that is, it is relative. Two observers that differ in their position and movement will differ in their measurement of the time of an event, so this magnitude will always be linked to a reference point.

This distinction **arose after the formulation of** Albert Einstein's **Theory of Relativity** and its profound impact on the field of physics. According to her, there is no single time and the perception of it may be delayed under certain physical conditions.