Edexcel iGCSE Physics -5.1 Units for Temperature, Energy, and Pressure- Study Notes- New Syllabus
Edexcel iGCSE Physics -5.1 Units for Temperature, Energy, and Pressure- Study Notes- New syllabus
Edexcel iGCSE Physics -5.1 Units for Temperature, Energy, and Pressure- Study Notes -Edexcel iGCSE Physics – per latest Syllabus.
Key Concepts:
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SI Units Used in Physics
In physics, all calculations must use SI units. Using the correct unit is essential for accurate calculations and full exam marks.
Common SI Units and Quantities
| Quantity | Unit | Symbol |
|---|---|---|
| Temperature | degree Celsius / kelvin | °C / K |
| Energy | joule | J |
| Mass | kilogram | kg |
| Density | kilogram per metre cubed | kg/m³ |
| Length | metre | m |
| Area | square metre | m² |
| Volume | cubic metre | m³ |
| Speed | metre per second | m/s |
| Acceleration | metre per second squared | m/s² |
| Force | newton | N |
| Pressure | pascal | Pa |
Important Unit Relationships
Temperature Conversion
\( \mathrm{temperature\ in\ K = temperature\ in\ ^\circ C + 273} \)
Density
\( \mathrm{density = \dfrac{mass}{volume}} \)
\( \mathrm{\rho = \dfrac{m}{V}} \)
- Density unit: kg/m³
Pressure
\( \mathrm{pressure = \dfrac{force}{area}} \)
\( \mathrm{P = \dfrac{F}{A}} \)
- 1 pascal = 1 newton per square metre (N/m²)
Key Idea
- Always convert quantities into SI units before calculation.
- Incorrect units lead to incorrect answers.
- Most physics formulas are defined using SI units.
Important Points to Remember
- Volume must be in m³, not cm³.
- Area must be in m².
- Use kelvin when required in energy calculations.
Example
A metal block has a mass of \( \mathrm{2.5\ kg} \) and a volume of \( \mathrm{0.002\ m^3} \).
Calculate the density of the block.
▶️ Answer / Explanation
Use:
\( \mathrm{\rho = \dfrac{m}{V}} \)
\( \mathrm{\rho = \dfrac{2.5}{0.002}} \)
\( \mathrm{\rho = 1250\ kg/m^3} \)
Example
A force of \( \mathrm{500\ N} \) acts on an area of \( \mathrm{0.25\ m^2} \).
Calculate the pressure exerted.
▶️ Answer / Explanation
Use:
\( \mathrm{P = \dfrac{F}{A}} \)
\( \mathrm{P = \dfrac{500}{0.25}} \)
\( \mathrm{P = 2000\ Pa} \)