# Homework Help: Thermal Physics?

1. Feb 24, 2006

### metalmagik

Sounds like Chemistry to me. So our teacher sends us all home with packets full of info on things we've never covered in class and I've gotta do this. Here's one problem that I'm not sure if I did right.

What is the specific heat of a metal substance if 135 kJ of heat is needed to raise 5.1 kg of the metal from 20 deg. C to 30 deg. C?

The formula is "heat needed to raise temp" = (mass)(specific heat)(delta temp)

so I made it 135 = (5.1)(x)(10)

and I got 2.65 J/Kgdeg.C for specific heat. Is this correct? Thank you

2. Feb 24, 2006

### BobG

Almost correct. You overlooked one small thing. You need 135 kJ of heat. You either have 2,650 J/(kg C) or 2.65 kJ/(kg C).

3. Feb 24, 2006

### metalmagik

AH much appreciated thank you, if you or anyone else could answer another small question in this same topic i would appreciate it, I have a graph here separated into 5 different parts (A-B, B-C, C-D, D-E, E-F) It is a curve going upwards...I just need to know how to calculate the heat of fusion of the substance using the curve in the graph...I can use the formula and calculate the heat of fusion for each little piece but...do I add them after that? I'm just not really sure...any help is once again appreciated, if you need me to clarify or draw the graph I will, gladly. Thank you.