Heat to warm water
How much heat is needed to raise the temperature of 2 kg of water from 20 °C to 30 °C? (c = 4.2 kJ/kg·°C)
Answer C: explanation for every choice
A
This uses 0.2 kg instead of 2 kg.
B
This uses 1 kg instead of 2 kg.
C
Correct. q = mcΔT = 2 × 4.2 × 10 = 84 kJ.
D
This uses a 20 °C temperature change.
Takeawayq = mcΔT.
Equation usedHeat transfer
Next question →Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID cp70.