Edexcel iGCSE Physics -5.2P Specific Heat Capacity Units- Study Notes- New Syllabus
Edexcel iGCSE Physics -5.2P Specific Heat Capacity Units- Study Notes- New syllabus
Edexcel iGCSE Physics -5.2P Specific Heat Capacity Units- Study Notes -Edexcel iGCSE Physics – per latest Syllabus.
Key Concepts:
5.2P use the following unit: joules/kilogram degree Celsius (J/kg °C)
Unit: Joules per Kilogram per Degree Celsius (J/kg °C)
The unit joules per kilogram per degree Celsius (J/kg °C) is used to measure specific heat capacity.
Meaning of the Unit
- J → energy transferred
- kg → mass of the substance
- °C → change in temperature
1 J/kg °C means:
The energy required to raise the temperature of 1 kg of a substance by 1 °C.
Important Notes for Exams
- The unit shows that specific heat capacity depends on both mass and temperature change.
- A larger value of J/kg °C means the substance needs more energy to heat up.
- The unit may also be written as J kg⁻¹ °C⁻¹.
- Temperature change can be in °C or K (both give the same change).
Key Idea
- J/kg °C is a compound unit.
- It links energy, mass, and temperature change.
- Used only with specific heat capacity.
Example
A block of aluminium of mass \( \mathrm{2.0\ kg} \) has a specific heat capacity of \( \mathrm{900\ J/kg\,^\circ C} \).
Calculate the energy needed to raise its temperature by \( \mathrm{10^\circ C} \).
▶️ Answer / Explanation
Use:
\( \mathrm{E = mc\Delta T} \)
\( \mathrm{E = 2.0 \times 900 \times 10} \)
\( \mathrm{E = 18\,000\ J} \)
Example
Water has a specific heat capacity of \( \mathrm{4200\ J/kg\,^\circ C} \).
How much will the temperature of \( \mathrm{0.50\ kg} \) of water increase if \( \mathrm{2100\ J} \) of energy is supplied?
▶️ Answer / Explanation
Rearrange:
\( \mathrm{\Delta T = \dfrac{E}{mc}} \)
\( \mathrm{\Delta T = \dfrac{2100}{0.50 \times 4200}} \)
\( \mathrm{\Delta T = 1^\circ C} \)