Thermal Equilibrium Help

Question

anonymous · Answer

@surry99 I have an idea, but I need a little help

surry99 · Answer

What is your idea?

surry99 · Answer

Ok, you are correct for experiment 2..in fact you had three times the temperature change in one piece of copper vs the other which is in exact proportion to their masses...agreed?

surry99 · Answer

Hint for the 4th expt: you have 4 times as much copper as aluminum and what else is different between the materials?

surry99 · Answer

and what important property thermophysical property is different between them?

surry99 · Answer

...Cp is different...their heat capacities....agreed?

surry99 · Answer

calculate the ration of the Cp's...aluminum to copper

surry99 · Answer

q = mCpdeltaT...   but just do a search for Cp of aluminum and copper...no need to calculate them for this problem.

surry99 · Answer

Cp (aluminum) = ?
Cp (copper) = ?

surry99 · Answer

google search...

surry99 · Answer

http://www.engineeringtoolbox.com/specific-heat-metals-d_152.html

surry99 · Answer

if you check the link I sent you will see:
Cp (aluminum) = .91 
Cp (copper) = .39

So what is the ratio of aluminum to copper?

surry99 · Answer

.91/.39 = ?

surry99 · Answer

no problem...so you see for the 4th experiment you have two important things to consider:
1) the mass of copper/mass of aluminum is 4:1
2) but the heat capacity of aluminum to copper is 2.33:1
So they don't cancel out but it explains why the delta T's are closer in this experiment than experiment number 2

surry99 · Answer

yes but you must also see that the ratio of the masses has an effect as well

surry99 · Answer

make sense?

surry99 · Answer

no, heat capacity for a material is independent of the amount of material (look at the units for Cp...J/g*degree C) but the total amount of heat that a material absorbs or releases does depend on the mass.

surry99 · Answer

I am not mad....no problem at all.
Yes it is because of those ratios...the ratio of the masses and the ratio of the specific heats
explains why the delta T for experiment 4 is not as high as experiment 2

surry99 · Answer

I am here to help :)

surry99 · Answer

yes

surry99 · Answer

That is correct.

surry99 · Answer

your welcome....goodnight