The flashlight.

[Aslan]

Here's a few weird things to consider, using just a simple flashlight.

When you turn a flashlight on, does it:

a) weigh more
b) weigh less
c) weigh the same

A man is on a train that is traveling at 1/2 the speed of light. he has a flashlight. A second man is standing next to the tracks and he also has a flashlight. There is a sign up ahead. At the exact instant the man on the train is next to the man next to the tracks, they both turn on their flashlights (which are pointing at the sign). Does:

a) the light from the man on the train hits the sign first
b) the light from the man on the ground hits the sign first
c) both beams of light hit at the same time
d) only the light from the man on the ground reach the sign

Fun stuff. (Kudos for explaining why you picked what answers you do pick...)

:devil:

[krept]

1, b) weigh less, for some of the following reasons although all might not be correct.

battery is converting chemical energy to heat energy causing the filiment to glow which in turn releases photons. some chemicals involved should be gassing off... there might be some gain as well through oxidation but i believe net effect will be loss via gas.

as to the nature of photons, can't remember if they are considered "massless" but because they are affected by gravity that means they should have at least the smallest mass, correct? Perhaps this loss is realized on a subatomic level, via electrons jumping back and forth through their orbitals, eventually "coming to rest" at a lower level.

Again, even compensating for possible gain of atoms through processes like oxidation (whether or not that is the correct term) I'd say there is a NET loss of weight on a small scale, at least due to the battery gassing off... I know this happens with lithium batteries and Surefires have lithium... :D

2, c. No, how about a :)

the key question here is whether or not light instantly reaches it's own speed... i.e. is there any acceleration? If so, then I would THINK that the edge goes to the light from the guy on the train because it has "momentum" already relative to the sign? heck... I don't know LOL. How about same situation but using a car @ 50mph and shooting bullets instead? Would the bullet from the car hit the sign first? I just keep going back to those reaaaaly fast planes that are dropped from slower (but still fast) planes... kinda like when the speed of sound was broken. the inertia (property to remain at rest, here) is easier to overcome. so again... if photons have mass, they have inertia to overcome.

I say A.

good stuff indeed

cheers

[krept]

do you weigh more at after inhaling and exhaling a breath than you did before?

[Aslan]

I'll give a hint on the first one: E=MC^2 (The first question is basically a thought experiment that Einstein came up with.)

The second one has to do with the speed of light being a constant.

[Aslan]

do you weigh more at after inhaling and exhaling a breath than you did before?

There was a time when I could describe the Krebs cycle in detail.

Assuming that your blood gets a net gain of oxygen, you would weight more.

Assuming that the amount of oxygen in the blood remains constant, then you would weigh the same.

If you are asking if there is a difference in you weight with your lungs full, vs with your lungs empty, then probably a difference.

:devil:

[krept]

theory of relativity you refer to just says photons have mass then, right?

speed of light is constant, but that's like saying the car is going 50mph. is there instantaneous acceleration? I mean, literally... like 0 to C in no time at all.

[krept]

guess one breathing cycle would be no net gain... unless all of the water isn't given off? :crazy1:

http://www.purchon.com/images/aerobic.gif

[Aslan]

theory of relativity you refer to just says photons have mass then, right?

speed of light is constant, but that's like saying the car is going 50mph. is there instantaneous acceleration? I mean, literally... like 0 to C in no time at all.

pretty much the way Einstein described it, the flash light weighs less when turned on than it does when off. because the photons do have mass, which is measurable. So, the mass has to come from somewhere - the flashlight.

But, I'd expect a net weight loss after each use of the flashlight. You have the photons of the light beam, the heat radiated by the bulb, all of which should account for the weight lost by the flashlight.

As far as the speed of light, it is a constant in a given medium. 0 to full speed with no apparent acceleration.

all fun stuff....

:devil: