Velocity facts for kids
Velocity is a way to measure how fast something moves and in what direction. It tells you both the speed and the path an object is taking. For example, if a car moves 9 meters every second towards the east, its velocity is 9 m/s to the east.
Think of it this way: speed just tells you how fast you're going (like 60 miles per hour). Velocity tells you how fast you're going and where you're headed (like 60 miles per hour north). So, velocity needs both a number (its magnitude) and a direction.
Contents
Velocity in one-dimensional motion
When an object moves in a straight line, we call this one-dimensional motion.
Average velocity
To find the average velocity of an object, you look at how much its position changed (this is called its displacement) and divide it by the time it took to make that change.
Imagine you walk from your house to a friend's house. Your displacement is the straight line distance and direction from your house to your friend's house. The time is how long it took you.
The formula for average velocity is: 
Here, v stands for velocity, x for displacement (how far it moved in a certain direction), and t for time.
For example, if an object moves 20 meters (m) to the left in 1 second (s), its velocity (v) would be: 
Instantaneous velocity
Instantaneous velocity is different from average velocity. It tells you how fast something is moving at one exact moment in time. Think of it like the speed you see on your car's speedometer right now, not your average speed for the whole trip. Velocity can change from moment to moment.
Relative velocity
Sometimes, we measure velocity by comparing the motion of two different objects. This is called relative velocity. The second object is like a reference point.
For example, the Earth moves very fast around the Sun (about 67,000 miles per hour!). But when you're walking on Earth, you usually don't think about that huge speed. That's because you're measuring your velocity relative to the Earth, which is your reference point. If you wanted to know your velocity relative to the Sun, you would need to add the Earth's velocity to your own.
See also
In Spanish: Velocidad para niños
