Average velocity is a fundamental concept in physics that describes how fast an object moves in a specific direction. It is calculated by dividing the total displacement by the total time taken. Unlike speed, which only considers distance, velocity takes into account both magnitude and direction of motion.
There's an important distinction between average velocity and instantaneous velocity. Average velocity looks at the overall displacement over the entire time period, shown by the green line connecting start and end points. Instantaneous velocity, however, is the velocity at any specific moment, represented by the orange tangent line that moves along the curve.
Let's work through a concrete example to calculate average velocity. A car starts at position 10 meters at time 2 seconds, and reaches position 50 meters at time 8 seconds. The displacement is 50 minus 10, which equals 40 meters. The time interval is 8 minus 2, which equals 6 seconds. Therefore, the average velocity is 40 meters divided by 6 seconds, which equals 6.67 meters per second.
Here's a crucial distinction between velocity and speed. Imagine an object that starts at position negative 3 meters, travels to positive 3 meters, then returns to its starting point. The total distance traveled is 12 meters, but the displacement is zero because the object ends up where it started. This means the average velocity is zero, while the average speed is not zero. This example shows why direction matters in velocity calculations.