Velocity vs Speed: Definitions, Differences & Real-Life Examples
Velocity is a vector quantity; it requires both the magnitude and direction of the body's motion. The distance a body travels in a given amount of time in a fixed direction is its velocity. If we say we're travelling at 30 miles per hour, that's our speed; if we say we're travelling at 30 miles per hour north, that's our velocity. In this article, we are going to learn about velocity. We will also discuss its calculations and will be able to comprehend this term better with the help of velocity images given in this article.
Speed vs Velocity
What are Velocity and Speed?
Velocity is a measurement of the speed and direction of an object's movement. speed is referred to as a scalar quantity. The distance an object covers in a given amount of time is referred to as its speed. Speed is referred to as a scalar number since it takes into account only the speed of the object. The same units are used to measure both velocity and speed. The metre is the SI unit for both displacement and distance. Time is measured in seconds. The ratio of two, or the metre per second, is the SI unit of speed and velocity.
Different Forms of Velocity
A constant velocity is a speed that moves in a straight line with the same speed and direction.
A velocity that shifts in either direction or with both speed and direction is referred to as changing velocity.
When gravity takes control and causes it to fall toward the earth through the atmosphere, then the object's constant state velocity is referred to as its terminal velocity.
Speed and Its Forms
Speed at any moment is referred to as instantaneous speed.
The overall distance travelled in a given amount of time is known as average speed.
The amount of turns a body makes in one unit of time is known as its rotational speed.
The rate at which a body moves linearly along a circle is called tangential speed.
When any body's speed can be understood in relation to other bodies by comparing it to them is known as relative speed.
Facts About Velocity
Galileo was the first person to try to measure the speed of light.
The speed of light is 186,282 miles per second.
The speed of sound is 343.2 meters per second.
A particular black hole in the galactic center of the NGC 1365 Spiral Galaxy is rotating at a speed of 84 percent of the speed of light.
Summary
Velocity is the displacement covered by a body per unit. Velocity is a vector quantity whereas speed is referred to as a scalar quantity. Velocity and speed have different types. Then later on we learned about the different forms of velocity. Here we have seen, constant velocity, changing velocity and terminal velocity. We have seen different forms of speed. i.e. instantaneous, average, tangential, relative speed. We hope you enjoyed reading this article, in case of any doubts, feel free to ask in the comments.
FAQs on Facts About Velocity and Speed
1. What is the main difference between speed and velocity?
The main difference is that speed is a scalar quantity, while velocity is a vector quantity. This means:
Speed tells you only how fast an object is moving (its magnitude). For example, 50 km/h.
Velocity tells you both the speed and the direction of motion. For example, 50 km/h towards the East.
Therefore, an object's velocity changes if its speed changes, its direction changes, or both change.
2. What are the formulas for calculating speed and velocity?
The formulas for calculating average speed and average velocity are based on distance and displacement, respectively. As per the CBSE syllabus:
Average Speed = Total Distance Covered / Total Time Taken
Average Velocity = Total Displacement / Total Time Taken
Here, distance is the total path length travelled, while displacement is the shortest straight-line distance between the starting and ending points.
3. Can the speed of an object be zero? What about its velocity?
Yes, both speed and velocity can be zero. An object's speed is zero only when it is stationary or at rest. Since velocity includes speed, the velocity of a stationary object is also zero. However, an object's average velocity can be zero even if its speed is not, for instance, if it returns to its starting point after a journey.
4. Can an object have zero average velocity but non-zero average speed? Explain with an example.
Yes, this is a key concept. An object has zero average velocity when its total displacement is zero, but it can have a non-zero average speed if the total distance covered is not zero. A classic example is an athlete running one full lap around a circular track. When they finish at their starting point:
The total distance covered is the circumference of the track (e.g., 400 metres), so the average speed is non-zero.
The displacement is zero because the final position is the same as the initial position. Therefore, the average velocity is zero.
5. What does a negative velocity signify? Why can't speed be negative?
A negative velocity simply indicates the direction of motion. In physics, we often define a certain direction as positive (e.g., moving to the right). Any motion in the opposite direction (moving to the left) is then described with a negative velocity. It does not mean the object is slowing down. On the other hand, speed cannot be negative because it is a scalar quantity that only measures the magnitude (the 'how fast' part) of motion, which is always a positive value or zero.
6. Under what condition is the magnitude of an object's velocity equal to its average speed?
The magnitude of an object's velocity is equal to its average speed only when the object moves along a straight line without changing its direction. In this specific case, the total distance covered is exactly the same as the magnitude of the displacement. If the object turns or reverses its direction, the distance travelled will become greater than the magnitude of its displacement.
7. How are uniform speed and uniform velocity different from each other?
The difference lies in the constraint of direction. An object moving with uniform speed covers equal distances in equal intervals of time, but its direction can change (e.g., a car on a circular track at a constant 60 km/h). An object moving with uniform velocity covers equal displacements in equal intervals of time, which means it must travel at a constant speed in a constant, unchanging direction (i.e., along a straight line).
