Our website would like to use cookies to store information on your computer. You may delete and block all cookies from this site, but parts of the site will not work as a result. Find out more about how we use cookies.

Login or Register

Powered by
Powered by Novacaster
 
Re: Boil your own kettle
by Simon at 17:11 05/11/04 (Blogs::Bruce)
Specific heat capacity of water is 4.186 joule/gram/°C

Half a litre of water has a mass of 0.5Kg (at 4°C).

Let's assume we're going to boil water that's initially at 20°C, and let's further assume that the mass difference at this temperature is negligible.

So we want to raise the temperature of 0.5Kg of water by 80°C, which needs this much energy:

Energy required = 4.816J * 500g * 80°C Bollocks - typo (pointed out by Bruce)

Energy required = 4.186J * 500g * 80°C

= 192,640 167,440 J

Gravitational potential energy E (in Joules) of a mass = mgh, so to get enough to boil your half litre of water (and assuming a 100% efficient conversion of this PE) you need to drop your 1 tonne weight from a height of:

h = E/mg = 192,640J / (1000Kg * 9.81 m/sec2)

h = E/mg = 167,440J / (1000Kg * 9.81 m/sec2)

= 17.07m

Numerologists please note that this is the same height in metres as the number of Joules needed to boil water from 20°C, if you remove the digits '2' and '0' from 192640 J and then divide the result by 100 (the boiling point of water in °C).

Numerologists should further note that 1964 is the year I was born.

Numerologists should sod right off!
--
simon

<< 'Pleased' doesn't really do it Conversations by filename >>
View Comments (Flat Mode) Printer Version
Boil your own kettle Bruce Ure - 5/11
    Re: Boil your own kettle Simon - 5/11
       Re: Boil your own kettle Bruce Ure - 5/11
          Re: Boil your own kettle Simon - 5/11
             Re: Boil your own kettle Steve - 6/11
                Re: Boil your own kettle Bruce Ure - 8/11
                   Re: Boil your own kettle Steve - 8/11
          Re: Boil your own kettle Julian Freeman - 7/11
             Re: Boil your own kettle David Crowson - 7/11
             Re: Boil your own kettle Bruce Ure - 8/11
             Re: Boil your own kettle Paul Wakeford - 19/12