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ncharles

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  1. ncharles

    Water Skiing

    By ncharles,

    Similar to tubing, another aquatic sport that i love to participate in is waterskiing. Something about gliding across the water gives me a sense of freedom that nothing else really does. Water skiing is a great example of physics too. Firstly are the turns. When a water skier decides to turn, they must angle their skis in such a way that makes them go where they want. Two main factors effect the turn: the angle and the force. The more of and angle the skier tilts the skis at the bigger and sharper the turn will be. However, skiers usually take long circular turns which require a much smaller angle. The "force" exerted by the person into the turn makes the turn faster or slower.  When the skier finishes their turn, they will next jump across the wake...a perfect example of projectile motion. The skier comes to the wake with a starting velocity that they must perfect: if too fast, they will over shoot the other side of the wake and if too slow they wont make it at all. Also, the make form a "ramp" of water at an angle to the surface of the water which the skier must also analyze to see how fast to go.
  2. ncharles
    Here in the North East, skiing and snowboarding is popular activity that many people participate in. However, most people don't think about the gobs of physics behind gliding or falling down the hill. For the more skilled skiers and snowboarders, the experience of tumbling down the slope is not very present in their time on the mountain. So, the main physics behind their ride is friction and gravity. Obviously, gravity allows them to move and accelerate down the mountain. However, what many people don't think about is friction. Although very small, the friction between the bottom of the board and the snow actually plays a large roll in the speed of the person. The main factor to decreasing the friction is coating the bottom of the board in wax. This makes the board ever smoother and decreases the coefficient of friction between the snow. Without this, the board has a tendency to reach a maximum velocity and not speed up after that, which for people who want to go very fast, is not appealing. So next time you go hit the slopes, make sure you wax you skis or board to go as fast as possible.
  3. ncharles

    When Pen Meets Paper

    By ncharles,

    Nearly every person in the world will, at one point in their life, use a pen to record, solve of draw something on paper. However, no one stops to think how and why this luxury occurs. How does ink come out of the pen when writing but not while just sitting there? A few main factors determine the flow rate of the ink: the pulling power of the pores of the paper, the pulling power of the pen and the surface tension of the ink. The pores of the paper act like little mini hands that grab on to the surface of the ink at the tip of the pen; rougher paper will pull out ink more quickly, while smooth surfaces struggle to pull out ink.  Then, due to the surface tension of the ink, as some of the ink is pulled out, more comes with it. When the pen is not writing, there is nothing to pull the ink out so no ink flows out of the tip of the pen. Also, when the pen is moving, another factor that contributes to ink flow is the speed of the pen: when its moving faster, ink flows out at a faster rate. Now, when ever you write something, you will think about how you are actually making words.
  4. ncharles

    Winter Driving

    By ncharles,

    As all Rochesterians know, winter driving is not easy and can get out of hand very easily. But why? Well it is rather simple. The added snow and ice on the road causes the coefficient of friction between the tires and the road to be much much smaller. Using the equation Ff=uFn with Ff being the force of friction, u being the coefficient of friction and Fn being the normal force we can see that when the coefficient of friction decrease (while the normal force is kept constant) the force due to firkin decreases. This causes the tires to slip a lot easier on the snow and ice than it would in just dry pavement. Similar to driving on snow/ice is driving on water. Although not a sever, when the road is wet the coefficient of friction between the tires and the parent is less than dry parent but not as less as snowy or icy pavement. So when you go driving this week be extra careful and be ready for a spin out.
  5. ncharles

    Zip-Lines

    By ncharles,

    Something i have always wanted to do is go on a zip-line in a forest or down a hill. However, what i did not think about are the many applications of physics in zip lining. The most obvious the use of gravity to propel you down the line. Gravity will act down on you at the center of you mass and accelerate you in a wild ride of fun. The zip-line actually works by putting a contraption on the line that has multiple wheels in it. The line is notched in the wheels and a low amount of friction allows the wheels to spin very fast while traveling down the wire (pulled by the force of gravity). At he end of the zip-line the most common way to stop is using a spring. The spring will be coiled around the wire so that when you hit it, it cushions your impact. The more you compress the spring the harder it will push back on you which insures that you will not hit the wall/tree/post it is attached to.

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