The collisions create an effective drag force that is similar to what you feel when you stick your hand out a car window: as the car goes faster the drag force increases, and as the car slows down it decreases.
The collisions create an effective drag force that is similar to what you feel when you stick your hand out a car window: as the car goes faster the drag force increases, and as the car slows down it decreases.
碰撞会产生有效阻力，就像开车时将手伸出车窗的感受：阻力随车速增加而变大，车速减慢即变小。