Concept of Velocity and its Explanation on Vedantu
Velocity in physics is defined as a vector measurement of the direction and rate of the motion. To be specific, the velocity of an object can also be defined as the rate of change in the object’s position corresponding to a frame of reference and time. In simple words, the term velocity gives us an idea of the speed at which an object is moving in a particular direction. It is what tells how slow or fast something is moving. Let’s take an example where two objects are moving. Identifying which of the two objects is moving faster than the other one is easy if they both are moving in the same direction. However, determining the faster object is quite difficult if the two are travelling in opposite directions. Considering such difficulties and thus eliminating them, our scientists came up with the concept of velocity to help the observers in identifying the faster or slower objects with ease. Here, we will be going to discuss this concept in detail.
What is Velocity?
Velocity is a vector measurement of the rate of motion of an object and the direction in which it is moving. Hence, to determine the velocity as per this definition, we should be familiar with both the magnitude and direction. For instance, if an object travels towards the west at 5 meters per second (m/s), then its velocity will be 5 m/s to the west. A simple formula given below is the most common and easiest way to calculate velocity.
r = d / t
where,
r is the rate (sometimes denoted as v, representing velocity)
d is the distance the object moved
t is the time the object took to complete the movement
Units of Velocity
Although the SI unit for velocity is m/s (meter per second), it can be expressed in any unit of d/t (distance per time). Some of the units in which one can express velocity is miles per hour (mph), kilometres per second (km/s), and kilometres per hour (kph).
Initial and Final Velocity
Initial velocity is the speed (along with direction) of the object with which it starts moving. On the other side, the final velocity is the speed (along with direction) of the same moving object once it has reached its final position.
How to Find the Initial Velocity?
The initial velocity (vi) is the velocity of the object before a change due to acceleration. Hence, it can be calculated by using the below formula:
vi = vf - at
where,
vi = initial velocity (m/s)
vf = final velocity (m/s)
a = acceleration (m/s2)
t = time between the start and end of the acceleration (s)
How to Find the Final Velocity?
The final velocity of an object is equal to its initial velocity plus acceleration multiplied by the time it travelled, and can be given as:
v = u + aΔt
where,
v = final velocity
u = initial velocity
a = acceleration
t = time
As the equation shows; for a given object, you can calculate its final velocity by adding its initial velocity to the acceleration due to force multiplied by the time for which the force applied to it. The delta (Δ) in front of the time (t) displays the change in time, which can be written as tv − tu. Here, tv – tu is the time elapsed from u to v.
Speed and Velocity
Most of us often get confused by the terms speed and velocity, as the concepts of both of these terms revolve around how fast something is moving. Well, although the concepts are a bit similar, these terms are quite different from each other. The main difference between speed and velocity is that speed gives an idea of how fast the body is moving, whereas velocity not only gives the idea of the body's speed but also tells the direction in which it is moving. Speed is related to distance travelled, whereas velocity is to displacement. Average velocity, which is the total displacement by total time, is always either less than or equal to the average speed. It is so because the displacement can never be more than the distance travelled, whereas the distance travelled can be more than the displacement.
Difference between Speed and Velocity
The basic difference between speed and velocity is that the former has only magnitude, while velocity has both magnitude and direction. It means the velocity is the speed with direction.
Other Detailed Differences between Speed and Velocity are as Follows:
Speed is the quantitative measure of how fast a body is moving, whereas velocity measures not just the speed at which the body is moving but also the direction in which it is moving. In other words, speed determines only how fast something is travelling, while velocity determines how fast something is travelling, along with the direction of its movement.
As the speed emphasizes only the magnitude, it is termed as a scalar quantity. On the other hand, the velocity is a vector quantity as it focuses on both the magnitude and direction.
Speed is defined as the rate of change of distance, whereas velocity refers to the rate of change of displacement.
The average speed of a moving body can never be zero or negative. But, the velocity of a moving body can undoubtedly be zero.
Speed is distance/ unit time. On the other side, velocity is displacement/ unit time.
FAQs on Velocity
1. What is velocity?
The rate of change of an object's position with regard to a frame of reference is its velocity, which is a function of time. An object's speed and direction of travel (e.g. 60 km/h to the north) is similar to velocity. The branch of classical mechanics that explains the motion of bodies, velocity is a basic notion in kinematics.
Velocity is a physical vector quantity that needs both magnitude and direction to get defined. Speed is the scalar absolute value (magnitude) of velocity, and it is a coherent derived unit whose quantity is measured in metres per second (m/s or ms1) in the SI (metric system).
"5 metres per second east" is a vector. However, "5 metres per second west" is a scalar. When an object experiences a change in speed, direction, or both, it is said to be accelerating. Visit the website to know more.
2. What is meant by average velocity?
The rate of change of location with respect to time is defined as velocity, which is also referred to as instantaneous velocity to underline the distinction from the average velocity. In some applications, an object's average velocity, that is, the constant velocity that produces the same resultant displacement as a variable velocity in the same time interval, v(t), over some time period t, may be required. The following formula can be used to compute average velocity:
\[\bar{v} =\frac{\Delta x}{\Delta t}\]
The average velocity of an object is always less than or equal to its average speed. This can be seen by noting down that, whereas distance is always constantly on the rise. Displacement can result in a change of direction as well as a change in magnitude.
The instantaneous velocity (or simply velocity) can be thought of as the slope of the tangent line to the curve at any point on a displacement-time (x vs. t) graph, and the average velocity as the slope of the secant line between two points with t coordinates equal to the average velocity's time period boundaries.
3. What are the polar coordinates of velocity?
A two-dimensional velocity in polar coordinates is defined by a radial velocity, which is defined as the component of velocity away from or toward the origin (also known as velocity made good). The rate of rotation around the origin is angular velocity.
By dividing the velocity vector into radial and transverse components, the radial and angular velocities may be calculated from the Cartesian velocity and displacement vectors. Transverse velocity is the component of velocity along a circle centred at the origin.
4. Give an overview of speed
Most people mix the terms speed and velocity in regular conversation. However, in physics, they do not have the same meaning and are two separate ideas. One significant distinction is that speed has no direction. As a result, speed is a scalar. Velocity and average velocity need to be differentiated from each other. Just like we must distinguish between instantaneous and average speed. The magnitude of immediate velocity is known as instantaneous speed.
The distance travelled divided by the time elapsed equals average speed. As a result, whereas the magnitudes of instantaneous speed and velocity are always the same, the magnitudes of average speed and velocity might fluctuate dramatically. An object must have a constant speed in a constant direction to have a constant velocity. The object's motion is limited to a straight route when it has a steady direction. As a result, constant velocity motion in a straight line at a constant speed.
A car travelling at a constant 20 km/h in a circular path, for example, has a constant speed but not a constant velocity because its direction changes. As a result, the car is believed to be accelerating.
5. Describe velocity as a vector quantity
The rate at which an object changes its position is called velocity, a vector quantity. Consider a person who takes one stride forward and one step back at a rapid pace, always returning to the same starting place. While this would cause a frenzy of activity, it would also result in zero velocity. The motion would never result in a change in position because the person always returns to their previous posture. This motion has zero velocity because velocity is defined as the rate at which the location changes.
If a person in motion wants to increase their speed. They should make every effort to increase the distance they are displaced from their initial location. Every step must be taken to move that person further away from his or her starting point. The Vedantu app and website contain free study materials.
