1. What Is Distance?
Distance is the total length of the path an object travels. It does not matter how straight or curved the path is. We simply measure how much ground the object has covered.
For example, if you walk from your classroom to the playground, the total walkway you cover is the distance.
1.1. Distance as Path Length
If an object moves along a curved path, we measure the entire curve. If it moves in a zig-zag way, we measure all the turns. That whole path length is called distance.
1.2. Key Feature: Direction Does Not Matter
Distance is a scalar quantity. That means it has only magnitude (how much), and no direction. Whether you move forward, backward, or sideways, all movements add to total distance.
2. Distance in Everyday Life
We frequently use distance in our daily conversations. When you say, “My school is 2 km from my home,” you are talking about distance.
2.1. Common Real-Life Examples
- The distance you walk in the morning.
- The distance a bus travels in one hour.
- The distance an athlete runs around a track.
2.2. Curved and Straight Paths
In real life, many paths are not perfectly straight. Even then, we measure total distance by adding up the entire path length.
3. Distance Along Different Paths
An object may move along various paths, and distance depends entirely on the path taken.
3.1. Straight Path Example
If you walk straight from point A to point B, the distance is the length of that straight line.
3.2. Zig-Zag or Curved Path Example
If you walk through a crowded market taking many turns, the distance increases because you are taking a longer path.
3.3. Circular Path Example
When you walk around a circular park, each full round covers the distance equal to the circle's perimeter.
4. Measuring Distance
Distance is measured in standard units so that everyone understands the same measurement.
4.1. Standard Units
Common units include:
- meter (m)
- kilometer (km)
- centimeter (cm)
4.2. Using Instruments
We use measuring tapes, meter scales, odometers, and GPS devices to measure distance.
5. Distance Cannot Be Zero Unless There Is No Movement
If an object moves even a little, the distance becomes greater than zero. Only when the object does not move at all does the distance remain zero.
5.1. Example
If you walk 10 meters forward and then walk 10 meters back to your starting point, your total distance is:
\( 10 + 10 = 20 \text{ meters} \)
Even though you returned to the start, the path you covered counts fully.