Supporting friction:
1) Cycling - the friction between the tires and the road are necessary for the bike to function
2) Running - the friction between the athlete's feet and the ground surface is necessary otherwise the runner would fall over
3) Swimming - the friction in the water is required for the swimmer to be propelled forward
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Opposing friction
1) Swimming - the friction makes it more difficult for the swimmer to swim very fast
2) Bobsleigh - the aim is to go as fast as possible but the friction between the bottom of the sleigh and the ice slows it down
3) Diving - the friction between the diver and the water creates wasted Kinetic energy and sound energy whereas the aim is to be as streamlined as possible