Difference between Speed and Velocity

Speed vs. Velocity

What is Difference between Speed and Velocity?  In everyday usage, the terms speed and speed are used interchangeably, thus causing some problems and confusion; but it is good to know that in science and mathematics these concepts have different meanings.

Difference between Speed and Velocity

Here’s what the difference between speed and velocity.

Speed

In kinematics , speed refers to the rate or rate at which an object covers a distance. It is a scalar quantity. Climbing means that it is used to measure the magnitude or strength of something and in case of speed, what is measured is the relationship between a distance traveled and the time that is used to travel it. Unlike speed, speed is not vectorial.

Speed ​​is measured in meters, kilometers and miles per hour or per second. In the case of air and sea transport, the “knot” is used as unit and we say (knots per hour).

Galileo Galilei is considered the first person to measure speed considering the distance traveled by the object. Galileo defines speed as the distance traveled per unit of time.

There are two ways to measure speed: average speed and instant speed. The first is the total distance traveled during the time interval. For example: if an automobile covers the distance of 320 kilometers over a period of 4 hours, then the average speed would be 80 kilometers per hour (80 km / h).

The average speed does not describe the variations of speed that have occurred during the trip, such as traffic stops, reduction or acceleration of speed.

On the other hand, the instantaneous speed is the one that is shown in the speedometer at any given time. If during the driving, the driver looks at the speedometer, the instantaneous speed will be the one that it marks at that moment. If a person continues to drive at a speed per hour (example 50 km / h), the instantaneous speed will be considered as well; 50 km / h

Velocity

Velocity ​​is the rate or rate of change of position of an object, which is equivalent to a specification of its speed and direction of movement. Velocity ​​is a vector magnitude. It not only determines the speed of the moving object, but also the direction of that object.

In order to maintain a constant speed, an object must travel in a certain direction for a certain amount of time. If the object changes direction, its speed also changes. In the same sense, it is necessary that the route that follows the object in question is not curved or circular.

An object that moves in a circle and returns to its starting point is said to have a velocity of zero. For example: a car traveling in a circular circuit at 90 km / h, has a speed of 90 km / h; but does not have a speed.

We speak of vectorial quantity when the knowledge of both the magnitude and the direction of the object to be determined are required. The absolute scalar value (magnitude) of speed is known as velocity. So if there is no direction or direction is not speed, but velocity.

In relation to the above, another example that can be mentioned is the following: a car that travels at 70 km / h in a northerly direction is said to have a speed of 70 km / h, north.

The velocity is commonly used to determine the speed of an object and the changes of direction during each point of time in which the trip takes place. The change in velocity as a function of time is known as acceleration , whereas “deceleration” is known as “negative acceleration” and is written with the sign ( – ).

Also the displacement plays an important role in determining the speed of an object. The offset is the shortest distance from the start or starting point to the end position or other point.

Key Differences between Speed and Velocity

  • Speed ​​is a scalar magnitude, while velocity is a vector magnitude.
  • Speed ​​is the rate or rate at which an object covers a distance, while velocity is the change of position of an object, which is equivalent to a specification of its speed and direction of movement.
  • When it comes to speed, the object can change direction and yet its average speed will continue to count. On the other hand, if it is velocity, the object must follow a constant direction; if the direction changes, so does the velocity.
  • Example of speed : a car traveling at 50 km / h, went from 0 km / h to 30 km / h before reaching 50 km / h; even at some point could rise to 60. However, the average speed will be counted as the speed of the car (50 km / h).
  • Example of velocity : A car that goes in a straight line towards a particular direction is considered to have a speed. If the car goes north and has an average speed of 30 km / h, it will be said that its velocity is 30 km / h, to the north.
  • The classical formula for determining velocity is: \ mathbf {\ bar {v}} = \ frac {\ Delta \ mathbf {r}} {\ Delta t} where the V with the hairline above is the average velocity, Δ r is the displacement and Δt is the time.
  • The classic formula for calculating speed is V = d / t.