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# Electricity and energy Watch

1. Hello there,
Have a question: How much heat energy is required to raise the temperature of the water from 20 -80 degrees celsius. Also what's the formula and is there a triangle method to solve problem?. Thankyou.
2. This sounds like part of a larger question where you will be given information such as the mass of the water and the specific heat capacity of the water. And unless there is quite a lot of the question that you haven't told us, there is no need to talk about electricity in the answer at all.

The equation you need is probably "energy supplied = mass x specific heat capacity x temperature change". If that is the case, then no rearrangement is needed, but when you do have to do this, I would stronly recommend that you try using algebra rather than a triangle method - it is not hard algebra, and with some equations, there is no triangle method that can help you.
3. Sorry yes your right, a bigger question. 300g of water placed in a kettle, temperature increased from 20-80 degree celcius. Heat capacity of water 4180 J Kg-1. So how much heat energy required to raise temp of water 20-80 degrees celcuis. Hope this helps. Thanks
4. I can't think of anything more to say than is in my first post - the way to do it is in there!
5. Checked it out, sorted, thankyou.
6. (Original post by sharan laird)
Sorry yes your right, a bigger question. 300g of water placed in a kettle, temperature increased from 20-80 degree celcius. Heat capacity of water 4180 J Kg-1. So how much heat energy required to raise temp of water 20-80 degrees celcuis. Hope this helps. Thanks

The heat capacity of ANY material tells us how much heat energy is needed to raise the temperature of 1kg of that material by 1 celcius.

In the case of water, we need 4180 Joules to increase 1kg of water by 1 celcius.

Next we need to know how much water we have which we are told is 300g in other words 0.3kg.

So to raise 0.3kg of water by 1 celcius, simply multiply the two:

0.3 x 4180 = ? joules.

Finally, we need to know how many celcius the temperature rises.

We are told form 20 to 80 celcius.

I'm sure you can work out the answer now. What did you get?
Eh= m*c*temp= 0.3*4180*60=7.5*10 to the power of 4Joules
A bit messy, couldn't get the superscripts in.
8. (Original post by sharan laird)
Eh= m*c*temp= 0.3*4180*60=7.5*10 to the power of 4Joules
A bit messy, couldn't get the superscripts in.
Correct.

joules.
9. As for triangle equation (although I agree algebra is better for understanding it fully) they can be useful to get the basic understanding of the equation, for this problem it would be:
(the energy supplied(j))
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