1

A physics question

Sat 14 May, 2011 02:33 pm
I weigh 84 kilos, approximately.

If I take the speed of light (300 000 km/sec) and multiply it with itself that's approximately 90 000 000 000.

That, multiplied by my 84 kilos is 27 000 000 000 000 000, and according to this book I found that is kilowatt hours.

So if I was a nuclear bomb and I exploded, that is the amount of energy that would be released...

My question is, is this correct?
• Topic Stats
• Top Replies
Type: Question • Score: 1 • Views: 1,426 • Replies: 13
No top replies

Francis

1
Sat 14 May, 2011 02:49 pm
@Cyracuz,
No, you have a problem of units:

E= Joules
M= Kgs
C= ms (metres/second)
Cyracuz

1
Sat 14 May, 2011 02:55 pm
@Francis,
I know.

But if we use the value 299,792 that is km/s

And then the number is 7 549 520 434 176, and according to that book that figure would be kw/h.

I am no mathematician and no physicist, so I think it is very likely that this is very wrong
0 Replies

raprap

1
Sat 14 May, 2011 02:58 pm
@Cyracuz,
E= mc^2

m=87 kg ~ 9E4 gram with rounding

c= 3E10 cm/s

c^2= 9E20 cm^2/s^2

E=81E24 gr cm^2/s^2 ~ 8E25 gr cm^2/s^2

1 gm cm^2/s^2 = 1E-7 Joule

E=8E18 Joule

1 kw hour = 3.6E6 Joule ~4E6 Joule

E=8E18/4E6 kw hour = 2E12 kw hour

You may be to high by a factor of 10, I have to recheck the conversion.

Rap
Cyracuz

1
Sat 14 May, 2011 03:02 pm
@raprap,
Thanks rap. The first try was off by millions I think, and even though I think the second is probably off too that will not be due to my abusing the calculator
roger

2
Sat 14 May, 2011 03:08 pm
@Cyracuz,
The important question is how much it takes to set you off.
Cyracuz

2
Sat 14 May, 2011 03:21 pm
@roger,
Hahaha.. yes, I would like to know that, just so I don't do it by accident
0 Replies

BillRM

2
Sat 14 May, 2011 03:32 pm
@Cyracuz,
Quote:
So if I was a nuclear bomb and I exploded, that is the amount of energy that would be released...

A side comment a nuclear bomb only convert a tiny percent of it mass into energy.

You would need to be a anti-matter/matter bomb to reach your goal.
Cyracuz

1
Sat 14 May, 2011 09:19 pm
@BillRM,
Well, it's not actually my goal. It was a hypothetical situation, one I hope never to experience..
Fil Albuquerque

1
Sun 15 May, 2011 12:27 am
@Cyracuz,
...good ! we are all saved then !
BillRM

1
Sun 15 May, 2011 10:26 am
@Fil Albuquerque,
I just done the math and if our friend mass would be converted to energy if would be roughly the same as a 1890 megatons bomb.

For any one who wish to confirm this a megaton of TNT is 4*10^15 joules.
Cyracuz

1
Sun 15 May, 2011 10:49 am
@BillRM,
I gots the powah!!
0 Replies

Thomas

1
Mon 16 May, 2011 08:26 am
@Cyracuz,
Cyracuz wrote:
That, multiplied by my 84 kilos is 27 000 000 000 000 000, and according to this book I found that is kilowatt hours.

So if I was a nuclear bomb and I exploded, that is the amount of energy that would be released...

Depends on what you mean by "nuclear bomb". When you explode one of the nuclear bombs we've invented so far, that converts only a tiny fraction of their mass into energy. For your calculation to be correct, you would either have to plug this fraction into your equation, or you would have to be a not-yet-invented type of nuclear bomb that converts your whole mass into energy.

On top of that, as Francis pointed out, you're off by a factor of 1,000,000 because you used the wrong units. (If the left side of your equation expresses energy in Joule (kg * m/s), then you need to express light speed in m/s, not km/s, on the right side of the equation.)
0 Replies

raprap

2
Mon 16 May, 2011 08:59 am
Units--Units--Units

To check your calculations cancel your units algebraically. If you don't end up with the desired unit, your conversion is wrong.

Rap
0 Replies

Related Topics

How can we be sure? - Discussion by Raishu-tensho
Proof of nonexistence of free will - Discussion by litewave
Destroy My Belief System, Please! - Discussion by Thomas
Star Wars in Philosophy. - Discussion by Logicus
Existence of Everything. - Discussion by Logicus
Is it better to be feared or loved? - Discussion by Black King
Paradigm shifts - Question by Cyracuz

1. Forums
2. » A physics question