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# The Physics Of Rowing

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## Lindsay Burkland

on 5 December 2013

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#### Transcript of The Physics Of Rowing

The Physics of Rowing
Intro to The Stroke
when most people think of rowing they think of the movement of the stroke, but what they don't think of is the physics related to it. When rowing there are many physics concepts that go into making the boat move such as kinetic energy, momentum, drag, and power. throughout the stoke power and momentum help make the boat move while drag explains why there feels as though there is something pushing against the boat. kinetic energy talk about the amount of energy used in one rowing stoke which are all relevant to physics.
Kinetic Energy
kinetic energy is involved in the rowing stroke. As the rower puts her blade in the water all through out the drive she is using kinetic energy

For example if we wanted to find the kinetic energy of a lightweight rower who weighs 55kg and their boat is going at a speed of 5.5m/s we could do so by using the formula for kinetic energy.
Drag
Drag refers to the force acting opposite to the motion of an object moving in a fluid. In crew the object is the boat and the fluid is the water the boat is rowing through. The major kind of drag in rowing is skin drag due to the friction between the boat and the water. the rower must adjust their stroke to the amount of drag on the boat. so if there is a lot of drag the stroke will take longer than if there wasn't a lot of drag.
Momentum
Momentum is the measurement of a body of motion.
in rowing the momentum from the water is equal and opposite to the momentum from the boat.

going through the stroke, when the system is at rest the momentum equals zero.
Then once you have taken your stroke and the boat is moving the momentum will still equal zero because the water and the boat are moving in opposite directions as explained in this picture
Power
Power is another physics concept related to rowing. power is the amount of work done over a period of time but can also be written as force times velocity. power is what helps make the boat move through the water. throughout the drive the rower is applying and amount of work over a period of time.

During the stroke the average female rower applies about 350 N of force at a velocity of 5.5 m/s using the equation for power that equals about 1925 watts of power
Kinetic energy of the boat
To find the kinetic energy of the boat with all 8 rowers we can use the same formula and the same velocity of 5.5 m/s and using the weight of 530 kg for the boat and all eight rowers we can determine that the kinetic energy is 8016.25 joules
momentum of the boat
If we wanted to find the momentum of the boat we could use the equation for momentum
p=mv
the mass of the boat with all 8 of the rowers being 530kg and the velocity of the boat being 5.5m/s
we can see that the momentum would be 2915 kgm/s

to find the mass of the water being used to push the boat we can use the conservation of momentum M1V1=M2V2
M1 = 530 kg V1=5.5m/s v2=10m/s
we can determine that the mass of the
water being used to push the boat
is 291.5 kg

In order to understand how these concepts fit into rowing here is a video of the stroke. shown in the video as the rower goes up to put her blade in the water we call that the catch. When the rower has finished her stroke we call that the finish. While her blade is in the water we call that the drive and while her blade is out of the water going back up to the catch we call that the recovery.
with this formula we can determine that the average rowers kinetic energy is 831.875 joules
Abstract
In this presentation the relation of kinetic energy, drag, momentum,and power to Rowing will be discussed. Each of these concepts work together to make up the stoke of a boat to help the boat move. in this presentation an explanation and example will be given to show how these concepts relate to rowing.
Conclusion/ Summary
The relation of physics to rowing is a topic that I find very interesting as someone who has rowed for 5 years. It's fascinating to see how all of these concepts help move the boat through the water and win races. the concepts of momentum , kinetic energy, drag, and power help make up the rowing stoke and knowing more about this relation can help a rower improve their stroke.
Works cited
images:
http://www.wikipremed.com/image.php?img=010103_68zzzz104950_05901_68.jpg&image_id=104950

http://www.kayarchy.com/html/03thesea/007currents.htm

http://ritcheylogic.cust.shopatron.com/news_article.php?id=666

http://www.best-rowing-machines-reviews.the-best-review.com/tag/concept-ii-rowing-ergometer-machine/

Video:
from YouTube titled good rowing example

Continued...
During the winter when rowers have to practice indoors rowers practice on a rowing machine called an ergometer (Pictured below) to help with their technique. Along with helping with technique rowers can adjust the amount of drag to practice their stroke.
In this picture you can see that the rower has just started her drive and is pushing off her foot boards applying a great amount of force while moving at some velocity
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