Heat: Common Mistakes (Form 4 SPM Physics)

The mistakes, and the fix

1. Q = mcθ, Use the value of c given in the question, and keep temperature change (not absolute temperature) in °C.
2. Q = mL, During a change of state the temperature stays constant, so there is no θ term. Use the correct L (fusion for melting, vaporisation for boiling).
3. p₁V₁ / T₁ = p₂V₂ / T₂, Temperature must be in kelvin (K = °C + 273). Volume may be in any unit as long as both sides match.
4. p₁V₁ = p₂V₂, Valid only at constant temperature for a fixed mass of gas. Pressure and volume are inversely proportional.
5. V₁ / T₁ = V₂ / T₂, Temperature must be in kelvin. Valid only at constant pressure for a fixed mass of gas.
6. p₁ / T₁ = p₂ / T₂, Temperature must be in kelvin. Valid only at constant volume for a fixed mass of gas.
7. In the Determining the specific heat capacity of aluminium practical, skipping this: Wrap the block in insulation to reduce heat loss to the surroundings.
8. In the Determining the specific heat capacity of aluminium practical, skipping this: Put a drop of oil in the thermometer hole for good thermal contact.
9. In the Determining the specific latent heat of fusion of ice practical, skipping this: Use a control funnel to correct for ice melted by the surroundings.
10. In the Determining the specific latent heat of fusion of ice practical, skipping this: Start only when the ice is dripping at its melting point (0 °C).
11. In the Pressure and volume of a fixed mass of gas at constant temperature (Boyle's law) practical, skipping this: Change the pressure slowly and wait so the gas returns to room temperature (constant temperature).
12. In the Pressure and volume of a fixed mass of gas at constant temperature (Boyle's law) practical, skipping this: Read the length of the air column at eye level to avoid parallax.
13. In the Volume and temperature of a fixed mass of gas at constant pressure (Charles's law) practical, skipping this: Stir the water so its temperature is uniform.
14. In the Volume and temperature of a fixed mass of gas at constant pressure (Charles's law) practical, skipping this: Wait for the trapped air to reach the water temperature before each reading.
15. In the Pressure and temperature of a fixed mass of gas at constant volume (pressure law) practical, skipping this: Stir the water so its temperature is uniform.
16. In the Pressure and temperature of a fixed mass of gas at constant volume (pressure law) practical, skipping this: Wait for the trapped air to reach the water temperature before each reading.

How a 1-to-1 teacher uses this list

In lessons the teacher marks a student's own work against this list, then re-teaches only the items that actually appeared, which is why 1-to-1 fixes habits that group classes miss.

More Heat resources

• Chapter overview: Heat
• Revision Notes
• Practice Questions
• Paper 2 Answering Guide
• Paper 3 Guide
• Key Terms
• Calculation practice sets

Source: DSKP KSSM Physics Form 4 and 5 (Versi English), Sijil Pelajaran Malaysia: Format Pentaksiran mulai 2021, Fizik (4531) (Bahagian Pembangunan Kurikulum (BPK), KPM)