During my summers in Sri Lanka, the sight of a large fruit bat electrocuted on the power line was not uncommon. Fruit bats in Sri Lanka, when compared to fruit bats in other parts of the world, are of an unusually large size. These bats often attempt to land on the power line in order to sleep but end up getting electrocuted because the tip of their wing touches another line. When their wing touches another power line, a voltage difference is established and the bat becomes the circuit for coulombs carrying 230 joules to travel through (the voltage in Sri Lanka is 230). However despite the hundreds of bats that die, there are still bats who manage to land on the power line without touching another and they sleep the night without danger. Only when a voltage difference is established is landing on a power line fatal.

My friend sent me this cartoon, among others, by email. The cartoonist depicts a scene between one worker and his fellow. One worker is disturbed because the vibrations of the other worker's leg is traveling through the ground and forcing his desk to vibrate. The forced vibration matches the natural frequency of his desk (or the frequency at which the object wants to vibrate) and thus the desk vibrates even harder. This is called resonance. That the shaking of one of the worker's leg could travel through the ground and cause the other's desk vibrate is a little far-fetched in my opinion. The joke of the cartoon is that instead of asking for the his co-worker to stop shaking his leg, the worker suggests instead that his co-worker change the frequency at which he shakes his leg so to match the natural frequency of the desk of yet another co-worker. If such is the case, resonance would occurs and if a drink were on the forcefully vibrating desk it would spill and thus the worker would have succeeded in frustrating his rival apparent.