Yes, absolutely. Acceleration can change even when speed remains constant.
Understanding Acceleration
Acceleration is fundamentally defined as the rate at which velocity changes. It's crucial to remember that velocity is a vector quantity, meaning it has both magnitude (speed) and direction.
As the reference states: "Acceleration is a change in velocity, either in its magnitude—i.e., speed—or in its direction, or both."
Therefore, acceleration occurs if:
- The speed changes (velocity magnitude changes).
- The direction of motion changes (velocity direction changes).
- Both the speed and the direction change.
The Key: Changing Direction
The reason acceleration can exist at constant speed is due to the direction component of velocity. If an object is moving but its path is curving, its direction of motion is constantly changing. Even if the object is covering distance at a steady rate (constant speed), this change in direction means its velocity is changing.
Uniform Circular Motion: A Prime Example
The most common and clear example of acceleration at constant speed is uniform circular motion. This is when an object moves in a circular path at a constant speed.
Consider the reference again: "In uniform circular motion, the direction of the velocity changes constantly, so there is always an associated acceleration, even though the speed might be constant."
- Constant Speed: The object covers the same distance along the circle's circumference in equal time intervals.
- Changing Direction: At every point in the circular path, the object's velocity vector is tangent to the circle. As the object moves, this tangent direction changes continuously.
Because the direction of velocity is changing, the object is accelerating. This acceleration is called centripetal acceleration, and it is always directed towards the center of the circle, causing the object to change direction and stay on the circular path.
Practical Examples
- A car turning a corner at a steady speed.
- An object on the end of a string being swung in a circle at a constant speed.
- The moon orbiting the Earth (approximately uniform circular motion).
In each case, the object's speed might be constant, but its direction of motion is changing, resulting in acceleration.
