# What consequences can the heat generated by our body have?

1. May 23, 2014

### DarkFalz

I know that this question may seem a bit weird at first glance, but i've been wondering about the following. Lets consider that someone throws a rock at me. I can either:

a) dodge the rock
b) take the rock head on

If i dodge the rock i will: produce heat moving away from the rock's path, produce more heat due to friction on the ground while doding

If i take the rock head on, none of the above will happen.

I know this might seem weird, but what consequences could the heat i produce have on the earth or the universe or even nearby people that could be worse than me taking the rock?

2. May 23, 2014

### dauto

No significant effect will come from that.

3. May 23, 2014

### DarkFalz

Maybe i am overanalyzing the matter, but what does one consider as significant? I can provide another exemple i've been wondering about. If i try to cut an apple with the blunt side of a knife by applying a force F, it wont cut, but if i try to cut the apple with the Sharp side of the knife by applying the same force F (which is enough to cut), what are the differences in physical terms? In the first scenario, i end up without cutting the apple, whereas in the second scenario i manage to cut the apple, but something has to be different in terms of physical state, even if all the conservation laws apply in both scenarios. What consequences can one situation have that the other one does not even though the second one seems the most favorable? In the end is it all up to the human needs to decide which consequences are indeed important?

I know that this might seem like a philosophical question, but i'd like to analyze it on physical terms.

4. May 23, 2014

### Staff: Mentor

Yes.

The heat generated by dodging the rock is so small that it has no noticeable effect on our world. If you were an electron things might be different.

5. May 23, 2014

### DarkFalz

What about effects other than the heat? Like possible consequences of the apple being sliced in two rather than staying as a single body. Maybe my question is starting to sound like a butterfly effect question, but i'd just like to understand where the consequences of every choice fit in the whole of the physical state.

6. May 23, 2014

### Staff: Mentor

Everything that happens is a consequence of a near infinite amount of previous consequences, so whether you take a rock on the head or cut the apple is, in the grand scheme of the universe, a tiny, tiny decision that builds up with countless other decisions to have some effect in the future. Predicting what will happen beyond the very near future is difficult, so I wouldn't worry about it.

7. May 23, 2014

### SteamKing

Staff Emeritus
I don't know about the OP personally, but all humans (the live ones, at least) generate heat due to their metabolism, 24/7/365, regardless of whether one is dodging rocks thrown at them or taking a header with it.
Maybe if we were all undead the situation would change.

8. May 23, 2014

### dauto

There could be huge effects. If you dodge the rock it might hit somebody else over the head and kill them for instance. It might also be inconsequential. No way to tell ahead of time. That's the nature of the unpredictability of the world. By the way, the consequences might be good as well. May be that person hit by the rock was Adolf Hitler...

9. May 23, 2014

### nasu

Heat is generated even if you take the rock head on.
The kinetic energy of the rock ends up as thermal energy in the end.
Even if some sound is produced, the energy of the sound is dissipated in the medium.

Actually if a rock is thrown and does not become a satellite, pretty soon its energy will end up as thermal energy. No matter what you do.
But these things have nothing to do with "good" and "bad".

10. May 24, 2014

### 256bits

None really. What's done is done, You can't go back and run the experiment again with a different set of conditions and observe the possible outcomes.

The butterfly effect is not as all cranked up as it is as a type of scientific lore as in reality. You waving your arms should be causing more disasterous typhoons then a butterfly flapping its wings so. And any helicopter would be then unleashing tremendous weather patterns of havoc all around the globe.

Deterministic systems such as billiard balls are sensitive to initial conditions. Chaotic systems much less so. Complex chaotic systems settle down,around a focus, or alternatively fluctuate between several foci. Feedback from the butterfy flap is washed over just by how a system reacts to all the inputs.

The broad scope of your question is more important than you realize. Nuclear power plants run simulations of "what if" scenarios. The military does the same and explores possible outcomes based on decisions of commanders, troops in the field, deployment of resources. Economics has some of its livelihood coming from decisions that you make - the choice between buying the red shirt or the CD - perhaps the decisions of the executives of the apparel company have more of a consequnce on the future of their company than you as one individual of millions.

Literature and movies, and not just science fiction, explore the concept also. Go watch Chinatown and see if you can figure out if the outcome of the child would be different if the private deltective had not taken the case of her mother and setting in motion all the following consequences and final outcome. War Games ( I think it is that ) - the computer finally decides for the sake of humanity, the best option is to "Do Not Play.'

Which in itself has consequences. You actually have at the least minimum 3 choices with the apple. Use the sharp edge of the knife, use the blunt edge, or do not attempt to cut at all.

11. May 24, 2014

### CWatters

One way to look at it would be to say that the blunt side of the knife spreads the force over a larger area of the apple so the pressure is lower. Play the video..

http://www.bbc.co.uk/learningzone/clips/force-pressure-and-surface-area-how-sharp-is-a-knife/20.html

12. May 24, 2014

### CWatters

Google suggests that even at rest a human generates about 70w of heat.