# Procrastination of my reserch projec

1. Jun 6, 2005

procrastination of my reserch project has brought my ADD to this particular subject lol, say you dropped a lightbulb from somewhere very high up, say, from a commercial jet altitude, or any other in witch would change the factors
now my main question is how, or when would it it shatter, if it did. obviosly i know it would break upon hitting the ground, but, first there is the factor of heat built up in falling, might that do it? or the lack of pressure inside the bulb and the steady increace in air pressure as it is dropped. the one i just thought of however was how it would fall, i am assuming that it would fall with the metal downwards as it 1. has the center of gravity and 2. would make the fall more aerodynamic. now as for this, i realised there is a spiral on the metal part of the bulb, so as to plug into the socket, this idea i had was that perhaps while falling, the bulb would begin to spin, probably very rapidly, might this 1. increace the air friction on the glass and make it hot enough to melt/break or 2. my origional thought, make the centrificul forse so great the bulb shatters apprt from all the force.

i really should be doing my homework now but i would like some feedback on my little break from responsibility lol

Last edited: Jun 6, 2005
2. Jun 6, 2005

### mewmew

I would say it would fall with little spin and not break untill it hit the ground. Perhaps others that are smarter could prove me wrong however. I get this from just watching how lightbulbs fall from small heights. Its terminal velocity can't be that high I would assume, as its mostly empty and has a large surface area for its mass.

Last edited: Jun 6, 2005
3. Jun 6, 2005

rigth, so i tyhought that the large surface area might make friction an issue, and with the added spin it might increace, it would probably break around a certain altitude dropped from.
just thought of it, a lightbulb falling right in front of you and exploding beore it hit the ground, that would be interesting, although not at all the reason i came up with this lol

4. Jun 6, 2005

### Crosson

I wont bother to work it out, but if you know a little physics here is how you could answer the question:

When the bulb was dropped, all of its energy was stored as gravitational potential. When the bulb was falling, its gravitational potential energy was converted in to kinetic energy AND the energy due to heat from friction.

Because energy is conserved, the heat in the bulb is the difference between gravitational potential at the top and kinetic energy at the bottom (ignoring heat dissapation).

Using some engineering data, you can compare the expansion due to the amount of heat the bulb incurred with the maximum expansion rates for glass.