# Uniform movement

When a mobile moves at a constant speed, it is said that this mobile is in a uniform movement (MU) Particularly, in the case that it travels with a constant velocity in a straight trajectory, there is a uniform rectilinear movement.

An important observation is that when moving at a constant speed, the instantaneous velocity of this body will be equal to the average velocity, since there will be no variation in velocity at any moment of the course.

The hourly equation of space can be demonstrated from the mean velocity formula. For example:
A shot is fired at a target attached to a large wall capable of reflecting the sound. The echo of the shot is heard 2.5 seconds after the moment of the blow. Considering the speed of sound 340m / s, what should be the distance between the shooter and the wall? Applying the hourly equation of space we will have: , but the echo will only be heard when the "back and forth" sound from the wall. So . It is important not to confuse the s which symbolizes the displacement of the s which means second. This is a unit of time. In order to have this differentiation, in the problem were used: s (for displacement) and s (to second).

 Know more… By convention, we define that when a body moves in a direction that coincides with the orientation of the trajectory, ie forward, then it will have a v> 0 and a > 0 and this motion will be called progressive motion. Similarly, when the direction of movement is contrary to the direction of direction of the path, ie backwards, then it will have a v <0 and a <0, and the movement will be called retrograde motion.