Speed vs. Velocity
* Speed: A scalar quantity, meaning it only has magnitude (amount). It tells us how fast an object is moving.
* Velocity: A vector quantity, meaning it has both magnitude and direction. It tells us how fast an object is moving *and* in what direction.
Can a particle have zero speed and non-zero velocity?
No, a particle cannot have zero speed and non-zero velocity.
* If a particle has zero speed, it means it is not moving at all.
* If it's not moving, it cannot have a direction of motion.
* Therefore, if the speed is zero, the velocity must also be zero.
Key Point: You can have zero velocity without zero speed. Imagine a particle moving in a circle at a constant speed. While its speed remains constant, its velocity is constantly changing direction, resulting in a net velocity of zero over a complete circle.
In conclusion: A particle can have zero speed, in which case its velocity is also zero. It cannot have zero speed and non-zero velocity simultaneously.
