Understanding Average Velocity
* Average velocity is the total displacement divided by the total time taken. Displacement is the change in position, a vector quantity that considers both magnitude and direction.
* Instantaneous velocity is the velocity at a specific moment in time.
The Scenario
Imagine an object moving in a straight line. If the object moves forward during the first half of the time interval and then moves backward an equal distance during the second half, the total displacement will be zero. Since displacement is zero, the average velocity will also be zero, even though the object was moving during the first half of the interval.
Example
Let's say a car travels 10 meters to the east in 5 seconds (first half of the interval) and then travels 10 meters to the west in the next 5 seconds (second half of the interval).
* Displacement: The car ends up back where it started, so its total displacement is 0 meters.
* Average velocity: (Total displacement) / (Total time) = (0 meters) / (10 seconds) = 0 m/s
Key Point: The average velocity being zero doesn't mean the object was stationary throughout the entire interval. It simply means that the object's net change in position was zero.
In other words, the object could have been moving during the first half of the interval, but its motion during the second half precisely canceled out its initial movement, resulting in a zero average velocity.
