The Difference Between Speed & Velocity

Summary

In this video, the speaker explains the difference between speed and velocity. While both terms might seem similar, speed is a scalar quantity, representing only distance over time, whereas velocity is a vector, which includes direction. For example, if you're cycling at 5 kilometers per hour, that's your speed. However, if you cycle in a circle and return to your starting point, your velocity is zero since there's no directional change. The video clarifies these concepts with simple examples, helping viewers understand the fundamental difference between speed and velocity.

Takeaways

• 😀 The speaker is answering a question from a young physics student about the difference between speed and velocity.
• 🤔 The speaker once thought speed and velocity were the same but now clarifies the difference.
• 📏 Speed is a scalar quantity, meaning it only has magnitude (distance over time).
• 🧭 Velocity is a vector, which means it has both magnitude and direction.
• 🚴‍♂️ Speed example: If you ride your bicycle at 5 kilometers per hour to the park, your speed is 5 kilometers per hour.
• 🧭 Velocity example: If you move in a circle and return to the same point, your speed remains, but your velocity is zero because there is no directional gain.
• 🚶‍♀️ In the example of walking different distances in various directions, if you return to your starting point, your average velocity is zero.
• ↔️ Speed is like distance (how far you've traveled), while velocity is like displacement (how far you are from the starting point).
• 💡 The speaker offers to make a video explaining the difference between distance and displacement if viewers are unsure.
• 🎥 The speaker mentions working on longer videos while this one is a quick explanation.

Q & A

What is the key difference between speed and velocity?

The key difference is that velocity includes a direction, while speed does not. Speed is a scalar quantity, while velocity is a vector.

Why is speed called a scalar quantity?

Speed is called a scalar quantity because it only has magnitude (the rate at which an object covers distance) and does not include any information about direction.

Why is velocity referred to as a vector quantity?

Velocity is referred to as a vector quantity because it includes both magnitude (the rate of motion) and direction.

Can you provide an example of speed and velocity using the same numerical value?

Yes. If someone is traveling at 30 kilometers per hour, that is a measure of speed. If they are traveling at 30 kilometers per hour toward the north, that becomes velocity since it includes direction.

How does the example of a cyclist going to the park illustrate speed?

In the example, the cyclist travels at a constant speed of 5 kilometers per hour to the park. The speed is simply the distance covered divided by the time taken, which is 5 kilometers per hour.

What happens to the velocity of the cyclist if they return to the same starting point?

If the cyclist returns to the same starting point, their velocity becomes zero because the displacement (change in position) is zero, even though they traveled a certain distance.

Why is velocity zero even if the cyclist was moving at a speed of 5 kilometers per hour?

Velocity depends on the displacement. If the cyclist returns to the starting point, their displacement is zero, making the velocity zero, despite having a non-zero speed.

How is displacement related to velocity?

Displacement is a vector quantity that refers to the change in position from the starting point. Velocity is dependent on displacement, not the total distance traveled.

What would be the average velocity if someone walked in a square and returned to the starting point?

The average velocity would be zero because the person ends up at the starting point, meaning there is no change in position or displacement.

How is distance different from displacement?

Distance is the total length of the path traveled, while displacement is the shortest straight line between the starting and ending points, including direction.

Outlines

00:00

📧 Introduction and Question from a Student

The speaker introduces the video by mentioning that they are working on various interesting projects. They are responding to an email from a young physics student, who asks a question about the difference between speed and velocity. The speaker expresses that this is an excellent and insightful question, even admitting that they once thought the two terms were the same.

⚡ Defining Speed vs. Velocity

The speaker explains that speed and velocity are not the same. Speed is a scalar quantity, meaning it only describes magnitude (distance over time), while velocity is a vector, which includes both magnitude and direction. For example, '30 kilometers per hour' is a measure of speed, but '30 kilometers per hour north' describes velocity because it includes direction.

🚴 Simple Example: Riding a Bicycle

To illustrate the difference, the speaker gives an example of riding a bicycle at 5 kilometers per hour. The speed is simply the distance covered over time. However, if the rider moves in a circle and returns to the starting point, the velocity is zero because there has been no change in the directional displacement, despite the speed being 5 kilometers per hour.

🔄 Clarifying Velocity with Directional Change

The speaker further explains that even if you move in different directions (e.g., 4 meters forward, 2 meters sideways, etc.), the average velocity could still be zero if you return to the starting point. This is because velocity depends on the net change in direction or displacement, not just the distance traveled.

💬 Conclusion and Call for Engagement

In closing, the speaker highlights that the difference between speed and velocity is similar to the distinction between distance and displacement. They invite viewers to comment if they need further clarification, offering to make additional videos on related topics. The speaker wraps up with a quick note, mentioning that longer videos are in the works.

Keywords

💡Speed

Speed is a scalar quantity that refers to how fast an object is moving, measured as distance over time. In the video, the speaker defines speed using the example of 30 kilometers per hour, emphasizing that it only accounts for the magnitude of movement and not the direction. It's simply the rate of travel, without concern for where the object is headed.

💡Velocity

Velocity is a vector quantity that refers to the rate at which an object changes its position, including both speed and direction. The speaker distinguishes it from speed by noting that velocity includes directional information, as in the example of 30 kilometers per hour to the north. Velocity is central to the video's explanation of motion, as the speaker contrasts it with speed.

💡Scalar

A scalar quantity is one that has only magnitude and no direction. The video explains that speed is a scalar because it describes how fast something is moving but does not account for the direction of that movement. This concept is key in differentiating between speed and velocity.

💡Vector

A vector quantity includes both magnitude and direction, making it more complex than a scalar. Velocity is an example of a vector because it not only tells us how fast something is moving but also in which direction. This distinction is vital to the main theme of the video, as the speaker repeatedly points out that velocity is speed with direction.

💡Distance

Distance refers to the total length of the path traveled by an object, regardless of its direction. In the video, the speaker mentions distance in the context of calculating speed (distance over time). It's important for understanding the concept of motion without considering where the object is relative to its starting point.

💡Displacement

Displacement is the change in position of an object, measuring the shortest straight-line distance between the starting point and the final position. Unlike distance, displacement considers direction, which connects it to the concept of velocity. The video hints at displacement when discussing scenarios where an object returns to its starting point, making the displacement zero.

💡Direction

Direction refers to the specific path along which something moves. The speaker emphasizes that velocity includes direction, such as moving north at a certain speed, making it different from speed. Direction is a core element in distinguishing vector quantities from scalar ones.

💡Circular Motion

Circular motion occurs when an object moves along a circular path. The speaker uses this example to explain how velocity can be zero despite an object moving at a constant speed. If an object returns to its starting point, its displacement is zero, and hence its velocity is also zero, even though it maintained speed throughout.

💡Average Velocity

Average velocity is the total displacement divided by the total time taken. The speaker uses an example of someone moving in various directions and ending up at the starting point, explaining that the average velocity is zero because the displacement is zero. This concept further emphasizes the importance of direction in calculating velocity.

💡Kilometers per hour

Kilometers per hour (km/h) is a unit of speed or velocity that measures how many kilometers an object travels in one hour. In the video, the speaker uses this unit to explain both speed (e.g., 30 kilometers per hour) and velocity (e.g., 30 kilometers per hour to the north), demonstrating how it applies to both concepts but changes when direction is added.

Highlights

Introduction to the topic and responding to a young physics student's email about the difference between speed and velocity.

Clarifies that speed and velocity are often confused, even the speaker once thought they were the same.

Explains that the key difference between speed and velocity is that velocity has direction, while speed does not.

Defines speed as a scalar quantity and velocity as a vector quantity in physics.

Provides an example of speed: '30 kilometers per hour' as it indicates distance over time, making it a scalar quantity.

Defines velocity as speed with a directional component, such as '30 kilometers per hour to the north.'

Introduces a simple bicycle example to explain the concept of speed: cycling at 5 kilometers per hour to a park.

Elaborates on velocity using the example of moving in a circle and returning to the starting point — speed remains, but velocity becomes zero due to no net displacement.

Further emphasizes that speed is the measure of distance over time, while velocity depends on directional displacement.

Compares the difference between speed and velocity to the difference between distance and displacement.

Offers to explain the concept of distance vs displacement further if there are requests in the comments.

Concludes the video by thanking the audience and mentioning upcoming videos.

The speaker adds that this was a short video ('quickie') while working on longer content.

The speaker invites audience engagement and feedback by asking viewers to comment below with questions.

Background music plays as the video comes to a close.

Transcripts

hello everybody today I'm answering an

email that I got from a young physics

student while I'm working on an array of

really cool videos that I'm sure you

guys are gonna like so the question is

what is the difference between speed and

velocity that is an interesting and

excellent question

because I - at some point thought they

were the same thing now as per usual I'm

going to tell you what the difference is

in words and then I will explain it with

an easy example so basically the

difference between them is that velocity

has a direction while speed does not in

physics we call speed a scalar quantity

while velocity is a vector that means

that if we take this expression 30

kilometers per hour just like that now

this is speed because it says distance

over time so this is by definition speed

as simple as that but for velocity now

this expression would look something

like 30 kilometers per hour in the north

direction or dear north now let's take a

look at a very simple example if you

took your bicycle and you want to go to

the park if you're riding your bicycle

at five kilometers per hour until you

reach the park then your speed is five

kilometers per hour is the distance that

you have covered in the time it took you

to cover it before velocity like I said

it has to do with the direction so for

example if you start from point A and

you go with that speed in a circle and

then you come back to point a again the

exact same point then we say your speed

here is five kilometre per hour but your

velocity here is zero and the reason it

is zero is because there is no

directional game you started it in the

same point and then you came back at the

same point again even if you were to

walk four meters this way two meters

this way four meters this way and then

two meters up here then your velocity or

average velocity is zero can

per hour the difference between the two

it's like the difference between

distance and displacement basically if

you're not sure about that one

comment below and I will make a very

quick video like this about it thank you

so much guys just a quickie today while

I'm working on different videos that are

longer now we'll see on the next one

[Music]