A rubber belt that goes around all pulleys & has idlers as tensioners. On cars there are either v belts (belts shaped like a "v" that are tightened by moving accessories) or serpentine, which is...
Yes. Acceleration is any change in velocity. When a car slows down it is decelerating; think of deceleration as acceleration in the negative direction.
In theory, a spoiler adds drag which would in fact slow down an object in motion. However, most popular vehicles with spoilers will never travel fast enough that the driver would really notice.
On...