Once again, it was through kayaking this Saturday that I found more real-world applications of physics concepts. I began to think about my kayak’s movement in relation to current. Similar to the boat simulations we have been doing in class, the kayak’s movement and direction is greatly affected by the current of the water. The Ala Wai canal current is unusual because there is a current going both vertically, up and down the canal and horizontally, left to right across the canal. It is much easier to feel the effects of the up and down current, as I felt myself moving much more quickly and with less effort down the canal, while paddling up the canal against the current required more effort.
The horizontal current flowing across the canal left to right is more difficult to deal with in the kayak. I had to make adjustments in my direction to stay on course and travel in a straight line. Using an average vertical speed for the kayak of 2 m/s and an average current speed of .1 m/s I can calculate the angle change I need to make to travel in a straight line. With a vertical vector of 2 m/s heading South and a horizontal vector of .1 m/s heading East a right triangle can be formed. The hypotenuse of the triangle is my actual speed I am traveling at, the angle of the triangle is the directional angle I must be traveling in, in order to maintain a straight line path. Using the Pythagorean theorem, a2+b2=c2, the hypotenuse can be calculated: .12+22 = 2.0022 The actual speed I am traveling at is therefore 2.0155 m/s. The direction I am traveling at can be found by taking the tan-1 of the right triangle. Tan-1(.1/2) = 2.86 Degrees West of South. While the effect of the current may not seem large, causing only minute changes in direction, over the course of a race it can have quite a large effect and if it is not adjusted for, the current can move a kayaker far off course. Using physics though, a kayaker can adjust for current and travel in a straight path to the finish line.
matthewbeattiecallahan 