Wednesday, October 19, 2011

Physics of rowing

For my Physics News, I decided to look at my sport, rowing.

In rowing there are many physics principles used. To name a few, rowing uses propulsion, resistance, kinetic energy, speed variation, center of mass, buoyancy and many others. For my presentation, though, I chose to focus on speed and power variation. In class we have focused mainly on averages of speed and power, but in rowing there is large variation in both speed and power over each complete stroke cycle.

As you can see in the graphs above, the speed varies depending on where the oar blade is in relation to the water. When the stroke is in the recovery phase (or out of the water), the speed decreases because there is nothing propelling the boat forward, but as the rower takes a stroke and catches the water with their blade, the speed of the boat increases. This alternating increase and decrease can also be seen in the power variation graph, with the power decreasing when the blade is recovering over the water and the power increasing as it is pulling through the water.

This alternating increase and decrease of speed can be observed in this Myth Busters clip where they tied a water-skier to the back of an mens 8+ to see if it could produce enough speed to allow a person to ski behind it. The increase and decrease of speed proved to be a significant problem, but it was found that with the right technique that there was a fast enough average speed to water-ski behind a boat. - written by Kate Thomson

(Start the clip at 5:30)