Here's a breakdown:

* Rate of change: This means how quickly something is changing.

* Position: This refers to the location of an object in space.

* Time: This is the duration over which the change in position occurs.

Key Points:

* Velocity is a vector quantity: It has both magnitude (speed) and direction. For example, 50 mph east is a velocity, while 50 mph is just a speed.

* Constant velocity: An object moving at constant velocity travels in a straight line at a constant speed.

* Changing velocity: An object can change its velocity in two ways:

* Changing speed: A car accelerating or decelerating changes its velocity.

* Changing direction: A car turning a corner changes its velocity, even if its speed remains constant.

Examples:

* A car traveling at 60 miles per hour north has a velocity of 60 mph north.

* A ball thrown straight up has a velocity that decreases as it goes up and increases as it comes down.

* A satellite orbiting Earth has a constantly changing velocity, even if its speed is constant, because it is constantly changing direction.