Opening Jars

When I was visiting my aunt in Minnesota, my younger counsins wanted nutella sandwiches for breakfast. To open the jar of nutella, my aunt used a jar opener much like the one featured here (I didn't have my camera at the time). I instantly connected this with the concept of torque. In order to open the jar, she needed to exert a torque, or force causing rotation, on the lid. Her torque was insufficient to open the lid without the help of the jar opener. How did the jar opener open the lid if the amount of force my aunt exerted was the same? It increased the lever arm, or distance from the axis. Increasing the distance is the only other way to increase torque other than increasing force.

My friend Wathsala, for no apparent rational reason, decided to go sky-diving. Why anyone would do something as counterintuitive as jumping out of a moving air plane hundreds of feets above the ground I can't explain but I can explain the multiple forces acting upon Wathsala as she falls. First and most obviously is gravity, as Newton's Third Law indicated, as the Earth pulls Wathsala down, Wathsala pulls the Earth up with equal force but due to extreme differences in mass, their respective accelerations are varied. Ideally as Wathsala falls she is accelerating at a rate of 9.8 meters per second per second. However, because of air resistance, her acceleration is actually decreasing as she reaches her terminal velocity. Terminal velocity is when air resistance is equivalent to force of gravity. If Wathsala were allowed to fall in an infinite space she'd reach terminal velocity. Unfortunately, there is a finite amount of space between the place where she jumped and the ground and so a parachute was needed to increase the air resistance enough so that it was safe to land.

As you may know, light
bulbs are an essential part of modern living. A lightbulb transfers electric energy to light energy. Alternating current is being fed to my house's power system from HECO. The electricity goes through wires in the wall and ceiling and into the bulb itself. A wire carrying current runs through the bulb, part of this circuit is tungsten. The electrons can not travel as fast in tungsten and therefore generates heat, part of which is converted to light. Though lightbulbs get the job done, much of the current used to produce light is wasted and released as heat energy.

Napoleon's Zealotry

In this photo taken during a weekend escapade to the beach, my overzealous Irish Setter Napoleon is charging towards my out-of-screen obese labrador T.J. Napoleon has to work much harder than usual to charge in the water because there is a resistance force to his movement: the water. The reason Napoleon can charge forward is because his limbs are exerting a force greater than the resistant force, and the net force is in the direction he wants to go. One might argue that this is impossible because of Newton's Third Law, for every action there is a equal but opposite reaction. But because of the friction Napoleon's paws have with the sand, Napoleon is able to propel himself forward at a sometimes dangerous speed.

In the distance, my sister and I are clinging for dear life to rubber donut-shaped floatation devices being dragged along at a high velocity by a motor boat on lake in southern Sri Lanka. The boat pulling us has established our net force in that direction and so, our subsequent acceleration is also in that direction. Newton's Second Law and equation acceleration = net force/ mass provides evidence for great net force. The net force is large enough to produce a large acceleration despite large masses. Perhaps if I knew the physics of the activity then, I would have been less scared. But as I did not, I cannot recommend the experience. The ordeal was heart attack-inducing.

The oil lamp on my dresser is at equilibrium. But though it is at equilibrium, there are forces acting upon it. The earth is pulling the lamp down and, in accordance with Newton's Third Law, the lamp is pulling the earth up. The lamp is pushing the box down and the box is pushing the lamp up. The air is pushing the lamp left and the lamp is pushing the air right, and so on and so forth. How can a lamp be at equilibrium with all these invisible forces at play, you ask? Well, because the forces acting on lamp are equal and opposite. Furthermore, even as the lamp pulls the earth up, to use a popular example, the earth's mass is so enormous than when plugged into the equation acceleration= net force/ mass, the division of the net force by so huge a number results in an acceleration so small it is negligent. What a pity. That is for lamp.

Where my little sister would be without a fan to cool her oven-like bedroom? Only God knows. Further proof that magnets are indeed the key to modern living. Magnets enable the conversion of electric energy into mechanical energy. As Christian Oersted and Andre-Marie Ampere discovered, there is a fundamental connection between magnetism and electricity. They discovered, that a current-carrying wire physically moves in the presence of a permanent magnet when there is a varying magnetic field (in this case the moving electrons of the current). This basic configuration of a magnet and current carrying wire is a rudimentary motor and that is the essentials of the essential fan.