Punahou Carnival Physics

Last weekend, while walking around the Punahou Carnival I had the strongest physics realization all year: All these rides are possible because of what we've learned in physics!!! Whipping out my iPhone, I began to take pictures of all the rides with the Snapture app (not on the app store) while fighting my way through the crowd. After getting home from a great carnival and reviewing my majorly blurry pics i stumbled upon this one which turned out surprisingly well. One of my favorite rides when I was little, the swings serve as a great example of rotation, angular velociy and acceleration, and centripetal force. As opposed to picking up speed tangentially, which is hard to measure since the direction of each rider is constantly changing, one could theoretically measure the angular velocity of the riders during the ride and the angular acceleration/deceleration as it starts and stops by measuring the change in the angle per second, and the rate at which that increases or decreases. Additionally, since this does experience angular acceleration it is safe to assume that something within the ride provides torque, or a force that causes an object to rotate. Lastly, since the swings are travelling in a circular motion, the riders are experiencing centripetal force, a force that varies in form (in this case the horizontal component of the tension in the chains that lead from each swing to the top) and causes the riders to travel in a circular motion until the centripetal force is overcome, in such case the riders would exit the circular motion tangent to the point where the force overcame the centripetal force, which fortunately didnt happen.

Tuning Physics

This weekend I got a call from my friend with a Toyota Celica who wanted to install a new pair of Eibach ProKit springs (very, very jealous). Since i did not think about the physics opportunities and was not aware a journal was due tonight (we did one last week mr k!) i never took a camera, and upon realizing it i took a snapshot of two pages of my January/February issue of Project Car, the very issue we used for directions for the 3 hour project. Naturally, the physics in the project came in the form of torque. However, this torque was not applied by the car as one might expect (sorry mr k, i kept bugging my friend to open the engine up so i could see the cams and where the real torque is generated but he wouldnt budge), but instead by our hands and tools as we removed the old crusty springs and struts and put in some brand new ones. First off, we used a spring compressor, which applies tangential force to the spring in order to compress it so it can be fit into the upper mount. To replace the old, crusted nuts we used WD-40 and a wrench, a perfect example of torque. Sometimes, when it was just too rusted over, I improve my torque through three different methods: pulled perpendicularly, extended my lever arm (the pipe trick works well on the larger ones) and by adding more force (ie calling my friend over to do it). We also used specialized tools that displayed properties of torque, such as an impact gun, which can spin the upper nut fast enough so the strut won't spin, and a torque wrench which let us apply the factory recommended specs by controlling specific measurements of rotational force. In addition, we swapped his rims from the factory steelies to forged ones, which help to provide a more ideal moment of inertia. As opposed to the heavy, concentrated factory rims, forged rims are lighter, stronger, and have a more ideal weight distribution which results in a faster and more appealing ride.