1) bobsleigh - the friction between the track and the skis of the sleigh slows the sleigh down. The aim of the sport is to go fast.
2) diving - friction between the diver and the water contributes to the massive splashes that you see when a high-diver gets a low score in a diving competition
2) diving - friction between the diver and the water contributes to the massive splashes that you see when a high-diver gets a low score in a diving competition