Monday, September 14, 2015

World Rowing Championships

Competitive rowing races take place over 2,000 meters, and in eight man shells at the professional level, are completed in around five and a half minutes. Clearly, these boats are moving quickly and the rowers are applying quite a bit of force. But just how hard are the rowers working (we will use force applied as a proxy for exertion)? The winning British crew completed the race in 5:36.19, attaining their terminal velocity of at 500m, and passing this point in 1:20. This crew (the rowers, oars, and boat) had mass of 932.9 kg. So, using kinematics, the boat accelerated at 0.156 m/s^2 and using Newton's Second Law the rowers applied 145.53 N, with each rower applying 18.19 N. This however, is just the x-component of the force applied, as a rower presses against a footplate that is at a 45 degree angle. Using some trigonometry, each rower applied 25.73 N.

Rowing involves many more forces than just that applied by the athletes' legs. The buoyant force, and minute forces applied to the boat by the athletes by their movement in the shell all contribute (since boats need to be balanced, the resultant of these small movements must equate to zero). Additionally, air resistance opposes the movement of the crew, which explains why the British did not continually accelerate throughout the race. This cursory consideration of rowing hints at how comprehensive a lesson in physics rowing can be. Click the link to watch the race from earlier this month!

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