Final answer:
The velocity of a car set to cruise control can change due to hills, wind resistance, roadway conditions, vehicle load, and potential mechanical issues.
Step-by-step explanation:
When a car is operating on cruise control at a set speed, various factors can cause the velocity to vary from the cruising speed. Changes in velocity might occur due to inclines, declines, wind resistance, roadway conditions, or vehicle load.
Hills are a common reason for velocity changes: when a car goes uphill, it may slow down, and the cruise control will respond by increasing throttle to maintain speed. Conversely, when going downhill, the car may exceed the set speed, and the cruise control will reduce throttle or apply engine braking. Wind resistance also plays a role; a headwind can slow the car down, prompting the throttle to increase, while a tailwind can speed the car up, causing the cruise control to reduce fuel supply.
Additionally, changes in the roadway conditions, like driving on wet or icy roads, can lead to loss of traction that momentarily affects velocity. If a vehicle carries a heavier load than usual, it might also affect the cruise control's ability to maintain constant speed, especially on inclines where greater power is needed. Furthermore, mechanical issues such as a loss of engine power or transmission problems could impair the ability of cruise control to sustain the set velocity.