This discussion focuses on the concepts of heat capacity and specific heat capacity, emphasizing their dependence on mass and material properties. Heat capacity, measured in J/K, indicates the amount of heat required to raise the temperature of an object, while specific heat capacity, measured in J/(kg·K), varies by material and reflects the energy needed to raise the temperature of a unit mass. The conversation includes practical examples using a metal 'X' with a specific heat capacity of 1000 J/(kg·K) to illustrate calculations for energy requirements based on mass and temperature changes. Participants are encouraged to derive definitions and units to deepen their understanding.
PREREQUISITESStudents studying thermodynamics, educators teaching physics concepts, and professionals in engineering or materials science seeking to understand heat transfer principles.
but the temperature of the object didn't increase though? it's the mass right?Orodruin said:per temperature increase.
No. The mass of each object remains the same. It is just that something of the same material that has twice the mass will take twice the energy to raise the temperature.ellieee said:but the temperature of the object didn't increase though? it's the mass right?
hmm I still don't get it.. Q2 was being derived through specific heat capacity, while Q4 was being derived through heat capacity, so what point can that prove?Steve4Physics said:@ellieee, try working through these questions, paying attention to units at all stages. Post your answers if you still have a problem.
A metal ‘X’ has a specific heat capacity of c=1000J/(kg·K).
(Note, a change of 1K is the same as a change of 1ºC, so the unit can also be written J/(kg.ºC).
Q1. How much energy is needed to raise the temperature of 1kg of X by:
a) 1K?
b) 5K?
Q2. How much energy is needed to raise the temperature of 3kg of X by:
a) 1K?
b) 5K?
Q3. What is the heat capacity, C, of a 3kg of block of X?
Q4. Using your answer from Q3, how much energy is needed to raise the temperature of the block by:
a) 1K?
b) 5K?
Q5. Compare your answers to Q2 and Q4. Are they the same? Do you see why?
It wasn't meant to prove anything! It was meant to provide some insight to help you answer your original questions!ellieee said:hmm I still don't get it.. Q2 was being derived through specific heat capacity, while Q4 was being derived through heat capacity, so what point can that prove?
heat capacity : J/KSteve4Physics said:It wasn't meant to prove anything! It was meant to provide some insight to help you answer your original questions!
Here' a different approach. Can you answer these:
What is the definition of the heat capacity of an object?
From this definition, find the unit in which heat capacity is measured.
What is the definition of the specific heat capacity of a substance?
From this definition find the unit in which specific heat capacity is measured.
You haven't given the definitions (in words). From each definition, you can work out the unit. Then you'll understand why the unit is used.ellieee said:heat capacity : J/K
specific heat capacity: J/kgK or J/kg °C