# Thermal physics calculations

1. Jul 23, 2008

### Confuzzled_VN

Hi..i was trying out some calculations i found on some site as practice for my exam this Friday and realised that i dont understand at all..
Everytime i tried something..my answers were wrong..

E.i

1. How much heat energy is needed to heat 4 kg of aluminium by 8 (degrees)C?

1. Energy = mC(delta)θ = 4 x 1200 x 8 = 38400 J

I dont understand where the 1200 came from..

Can anybody give me links to thermal physics and general physics notes and/or worked examples for me to try out?

2. Jul 23, 2008

### Staff: Mentor

It would help if one would write units with the numbers in a problem.

Energy = mC(delta)θ, where m is the mass (in this case 4 kg), C is specific heat (which is unique or specific to a material which would be in units of J/kg-K), and θ would be the temperature (in K or °C, and not to be confuse with an angle). Some people use T for temperature.

Here is a good site for some basic physics - http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html

and for the problem at hand - http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/spht.html

Table of specific heats - http://hyperphysics.phy-astr.gsu.edu/hbase/tables/sphtt.html#c1
Cp = 900 J/kg-K for Al in this table.

Please expend some effort and review the notes on Hyperphysics.

Thank you.