## Physics 8: Selected Student Questions/Observations

Spring Term, 2006

### Q/O #1

• What makes LEDs brighter than traditional light sources, although they are smaller in size and do they get hotter than traditional light sources? (Anon.)
• So I understand that lighter masses can be thrown further than larger masses thrown at the same force (i.e i can throw a baseball further than a bowling ball thrown at the same force). Yet why is it that i can throw a wet sponge further than a dry, lighter sponge (with the same of applied force for both)? With the lighter mass, the sponge should have a larger acceleration and go further (F=ma) but it doesnt...why? (Anon.)
• It is necessary to have Calories to do work, but why do people get fat from Calories? And then they need to exercise to burn off those Calories? Can't the Calories just burn off by themselves? (Anon.)
• What happens to a freeze-dried object if you put it in a microwave, since freeze-dried objects have no water? (Anon.)
• I went to Baja and observed that the tidal range of the Sea of Cortez is much greater than that here off the coast of San Diego. I know tides have to do with the gravitational pull of the moon, but why the difference? (E. Martin-Craig)
• Why is it that a car with a flat tire(s) requires more force to accelerate or maintain its velocity then a car with fully inflated tires? If less air means less mass then shouldn't the car require less force to accelerate just as quickly? (Anon.)
• When one unfolds a poster that has been rolled up for a long time, one finds that the poster is adamantly opposed to staying flat. Why is this so? (Anon.)

### Q/O #2

• Air resistance has an effect on the efficiency in miles per gallon for car. If I am driving 55mph, would the gas efficiency change between a normal day and a windy day? (J. Chan)
• If a perpetual machine is impossible, how can those paper-weights you find in gift shops (like a dolphin that swings back and forth) work? do they oscillate forever or are they eventually slowed to a stop by air resistance? (Anon.)
• Why do things break more easily when they're cold? (K. Joy)
• Why does the shower curtain stick to the tile wall if the tiles are wet? (Anon.)
• Why is it that you can feel the wind being blown out from the front of a fan, but cannot feel it being sucked in the back? (Anon.)

### Q/O #3

• I've noticed that certain patterns worn by people on TV show up as wierd wavy lines. Especially small checkered patterns. Does this have anything to do with pixels in the TV or light waves? (Anon.)
• Why is it that when you put your ear to a seashell you hear the sounds of the ocean? And why does it also sound weird to just cup your hand over your ear too? (Anon.)
• Why are all the planets round while smaller objects such as comets and meteors are not round? (Anon.)
• When I microwave a burrito on a napkin, afterwards the napkin won't come off the burrito. Why does this happen? (Anon.)
• Why, when you sing a particular letter at a particular pitch, does it sound different than when you speak that same letter at that same pitch? I'm assuming this has to do with frequency and harmonics, but I don't understand why singing and speaking sound different. If they are the same pitch and the same letter sound, souldn't they have the same frequencies, and therefore sound the same? (Anon.)
• At home I use a blue soap bar. but every time I lather it up, the lather is white. How come? Shouldn't it also be blue? (Anon.)

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