* Speed is the rate at which an object moves, regardless of direction. It's a scalar quantity (only magnitude).

* Velocity is the rate at which an object moves in a specific direction. It's a vector quantity (magnitude and direction).

Here are some examples:

* Scenario 1: A car traveling at 60 mph east changes its speed to 40 mph east.

* Speed changed: Yes (from 60 mph to 40 mph)

* Velocity changed: Yes (magnitude changed)

* Scenario 2: A car traveling at 60 mph east changes its direction to 60 mph north.

* Speed changed: No (still 60 mph)

* Velocity changed: Yes (direction changed)

* Scenario 3: A car traveling at 60 mph east changes its speed to 40 mph west.

* Speed changed: Yes (from 60 mph to 40 mph)

* Velocity changed: Yes (both magnitude and direction changed)

In summary:

* Any change in speed directly changes the magnitude of velocity.

* Any change in direction directly changes the direction of velocity.

Therefore, if either speed or direction changes, the velocity will always change.