Speed in physics means the speed of movement of any object (material point) in space. This value is different: linear, angular, average, cosmic and even superluminal. Among all existing varieties also includes instantaneous speed. What is this value, what is its formula and what actions are needed to calculate it - this is exactly what will be discussed in our article.

Instant speed: essence and concept

Even a primary school student knows how to determine the speed of an object moving in a straight line: it is enough to divide the distance traveled by the time spent on such a movement. However, it is worth remembering that the result obtained in this way allows us to judge the average value. If an object moves unevenly, then in certain sections of its path, the speed of movement can vary markedly. Therefore, sometimes a value such asinstant speed. It allows you to judge the speed of movement of a material point at any moment of movement.

### Instantaneous speed: calculation formula

This parameter is equal to the limit (denoted as limit, abbreviated as lim) of the ratio of displacement (coordinate difference) to the time interval during which this change occurred, provided that this time interval tends to reach zero. This definition can be written as the following formula:

v=Δs/Δt as Δt → 0 or so v=lim _{Δt→0 (Δs/Δt)}

Note that the instantaneous speed is a vector quantity. If the movement occurs in a straight line, then it changes only in magnitude, and the direction remains constant. Otherwise, the instantaneous velocity vector is directed tangentially to the trajectory of movement at each considered point. What is the meaning of this indicator? Instantaneous speed allows you to find out what movement the object will carry out per unit of time, if from the considered moment it moves uniformly and rectilinearly.

### Tips

In the case of uniform motion, there are no difficulties: you just need to find the ratio of the distance to the time during which it was overcome by the object. In this case, the average and instantaneous speed of the body are equal. If the movement is not constant, then in this case it is necessary to find out the magnitude of the acceleration and determine the instantaneous speed at each specific moment in time. For vertical movement, the effect of acceleration must be taken into account.free fall. The instantaneous speed of a vehicle can be determined using radar or a speedometer. It should be borne in mind that the movement in some sections of the path may take a negative value.

In order to find the acceleration, you can use the accelerometer or make a motion function and use the formula v=v0+a•t. If the movement starts from a state of rest, then v0=0. When calculating, it is necessary to take into account the fact that when the body decelerates (decreases in speed), the acceleration will be with a minus sign. If an object is in free fall, the instantaneous speed of its movement is calculated by the formula v=g•t. In this case, the initial speed is also 0.