4MtheTeacher Find the Speed o Light w marshmallows [Archive]

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Bill From Yorktown

10-06-2006, 11:30 AM

<a href="http://www.physics.umd.edu/ripe/icpe/newsletters/n34/marshmal.htm">http://www.physics.umd.edu/ripe/icpe/newsletters/n34/marshmal.htm</a>Finding the Speed of Light with Marshmallows-A Take-Home Lab Robert H. Stauffer, Jr., Cimarron-Memorial High School, Las Vegas, Nevada, USA I have heard that at 16 years old, Albert Einstein constantly wondered what it would be like to ride on a beam of light. Students in physics always seem to be fascinated by the properties of light. However, speed-of-light demonstrations often require extensive preparation or expensive equipment. I have prepared a simple classroom demonstration that the students can also use as a take-home lab. The activity requires a microwave oven, a microwave-safe casserole dish, a bag of marshmallows, and a ruler. (The oven must be of the type that has no mechanical motion-no turntable or rotating mirror. If there is a turn-table, remove it first.) First, open the marshmallows and place them in the casserole dish, completely covering it with a layer one marshmallow thick. Next, put the dish of marshmallows in the microwave and cook on low heat. Microwaves do not cook evenly and the marshmallows will begin to melt at the hottest spots in the microwave. (I leaned this from our Food Science teacher Anita Cornwall.) Heat the marshmallows until they begin to melt in four or five different spots. Remove the dish from the microwave and observe the melted spots. Take the ruler and measure the distance between the melted spots. You will find that one distance repeats over and over. This distance will correspond to half the wavelength of the microwave, about 6 cm. Now turn the oven around and look for a small sign that gives you the frequency of the microwave. Most commercial microwaves operate at 2450 MHz. All you do now is multiply the frequency by the wavelength. The product is the speed of light. Example: Velocity = Frequency ´ Wavelength Velocity = 2450 MHz ´ 0.122 m Velocity = 2.99 ´ 108 m/s This works in my physics class, often with less than 5% error. Then the students can eat the marshmallows.

Tall_James

10-06-2006, 12:23 PM

Big deal.  I've successfully time-travelled using a paper plate, 3 spears of asparagus and an old Gino Vanelli album.

mikeyboy

10-06-2006, 12:31 PM

Fuck.  I'm not sure I trust <a href="http://www.ronfez.net/messageboard/viewmessages.cfm/Forum/52/Topic/52785/page/The_Ron___Fez_Time_Machine" target="_self">Furtherman's machine</a> if it's powered by marshmallows.  With my luck, I'd end up inside the infamous cupcake.

phixion

10-06-2006, 12:40 PM

how come they never do the experiment that proves that atomic weight is really in the nucleus. when they shot subatomic particles at a plate of gold i think and a sheet behind it that would react to the presence of additional electrons, i always wanted to see that. most of the volume of matter is empty, nothingness i find that mind blowing.oh yeah and anything that that requires measurements must adhere to the Uncertainty Principle, so i abstain from work that may be wrong in the first place.god its amazing, considering i wouldnt go to physics class unless i was high, how much i remember. 9.8 m/s squared i never understood that though how do you square a second?mike?

Furtherman

10-06-2006, 12:54 PM

mikeyboy wrote: Fuck.  I'm not sure I trust <a href="http://www.ronfez.net/messageboard/viewmessages.cfm/Forum/52/Topic/52785/page/The_Ron___Fez_Time_Machine" target="_self">Furtherman's machine</a> if it's powered by marshmallows.  With my luck, I'd end up inside the infamous cupcake. My machine is powered by sugar beets and Jamenson Whiskey.  It's totally safe.  In moderation.

blakjeezis

10-06-2006, 01:57 PM

9.8 m/s squared i never understood that though how do you square a second? The second is squared because you're talking about acceleration, not velocity. An object does not travel towards the center of Earth's gravity at 9.8m/sec/sec, it accelerates at that speed. Meaning after one second it is traveling at 9.8 meters/sec; after 2 seconds it's traveling at 19.6m/sec; after 3 seconds 29.4m/sec and so on until it reaches terminal velocity.

BoondockSaint

10-06-2006, 02:00 PM

I have a friend in Wall, New Jersey who would love this.

Mike Teacher

10-06-2006, 02:09 PM

phixion wrote: how come they never do the experiment that proves that atomic weight is really in the nucleus. when they shot subatomic particles at a plate of gold i think and a sheet behind it that would react to the presence of additional electrons, i always wanted to see that. most of the volume of matter is empty, nothingness i find that mind blowing.oh yeah and anything that that requires measurements must adhere to the Uncertainty Principle, so i abstain from work that may be wrong in the first place.god its amazing, considering i wouldnt go to physics class unless i was high, how much i remember. 9.8 m/s squared i never understood that though how do you square a second?mike?Ok yer in a [really fast] car and you hit the gas, after one second yer going 10 meters a second, at two seconds yer at 20 meters per second, at three seconds, 30 meters per second, etc... a constant acceleration. Constant = speed changes but the rate of acceleration stays constant.You're accelerating 10 meters a second; every second. Some say that as 10 meters per second per second, aka 10 meters/(second)(second), aka 10 meters/second^2.People who have fallen from heights and survived often describe freefall not so much as falling but as being shot out of something or being 'pushed' downward', since you accelerate as you fall, until you hit either terminal velocity, or the pavement.

Mike Teacher

10-06-2006, 02:22 PM

Oh yeah i forgot the marshmallow thing I have not seen and will check out. very cool.The gold foil experiment showed yep, matter is made, almost all of it, of completely empty space. But it would seem these days empty space may not be so empty, but a bubbling foam of space-time where matter and energy literally pop in and out of existance.And the Uncertainty Principle, in its strictest terms, means you cant measure Both the positon and velocity of a particle at the same time. Measuring one destoys the other.As you said, we find the act of measuring something messes up the measurement. Lets say you wanna measure, to high precision, the temperature of something. Well, whatever you stick in to measure the temp, unless it's at the exact temperature already [and you cant know that already], will be hotter or cooler then what it's measuring, so to some small degree at least, the act of measuring destroys the measurement.

Bill From Yorktown

10-08-2006, 10:54 AM

BoondockSaint wrote: I have a friend in Wall, New Jersey who would love this. hence my title to the thread.  Glad to see M the T read it.  Now I'm off to cutting an apple pie slice in half, then half again, then half again 90 successive times :-P

Hottub

10-08-2006, 11:20 AM

People who have fallen from heights and survived often describe freefall not so much as falling but as being shot out of something or being 'pushed' downward', since you accelerate as you fall, until you hit either terminal velocity, or the pavement.I am giving my old brain a Pop Quiz.Would that be 9.8 m/sec?Thanks, Teach!

cupcakelove

10-08-2006, 11:41 AM

mikeyboy wrote: With my luck, I'd end up inside the infamous cupcake.If only you had that kind of luck.