Why does a large specific heat capacity of water keep coastal temperatures steady?

Water needs a lot of energy per degree, so it warms slowly by day and cools slowly at night, flattening the range.

Should m in E = mc dT be in grams or kilograms?

Kilograms, because specific heat capacity is in J per kg per degree; grams make the answer a thousand times too big.

S4 Physics: Heat Capacity and Heat Transfer Paper 1 (direct E = mc dT work)

2026-11-03

S · 4

Paper 1 does one job: make E = mc dT fluent, finding energy, mass or temperature rise from the other two.

Quick answer　420 kJ; 22.5 kJ; 12,600 J per degree; 336 s; 5,460 J; 66.7 C; 56 C; oil warms 2.1 times as fast; a larger specific heat capacity means a slower rise.

01　Paper details (check answers afterwards)

Item	Detail
Questions	10 questions
Suggested time	25 minutes
Difficulty mix	Foundation 4 · Intermediate 3 · Challenge 2 · Error redo 1
Chapter	Chapter: S4 Physics: Heat Capacity and Heat Transfer
Level	S4

02　Questions (10 items)

FoundationTwo kilograms of water is heated from 20 C to 70 C. Taking the specific heat capacity of water as 4,200 J per kg per degree, find the energy needed.
FoundationWhat does it mean to say a substance has a specific heat capacity of 900 J per kg per degree?
FoundationHalf a kilogram of aluminium is heated from 25 C to 75 C. Taking 900 J per kg per degree, find the energy absorbed.
FoundationWhat is the heat capacity of 3 kg of water at 4,200 J per kg per degree?
IntermediateA 500 W heater warms 2 kg of water from 20 C to 40 C. Ignoring losses, how many seconds does it take?
Intermediate0.2 kg of copper cools from 100 C to 30 C at 390 J per kg per degree. Find the energy released.
IntermediateA 1 kW heater runs for 7 minutes (420 s) in 1.5 kg of water. Ignoring losses, by how much does the temperature rise, to one decimal place?
Challenge0.3 kg of water at 80 C is mixed with 0.2 kg at 20 C. Ignoring losses, what is the final temperature?
ChallengeThe same heater warms 500 g of water and 500 g of oil of specific heat capacity 2,000 J per kg per degree. How many times faster does the oil warm?
Error redoA student writes that a larger specific heat capacity makes a substance easier to heat up. What is wrong?

03　Answers and one-line notes

#	Answer	One-line note
1	420,000 J (420 kJ)	The rise is 50 degrees, so E = 2 times 4,200 times 50 = 420,000 J.
2	One kilogram of it needs 900 J to rise by one degree	That is exactly the definition: energy per kilogram per degree, and a bigger value means a slower rise.
3	22,500 J (22.5 kJ)	The rise is 50 degrees, so E = 0.5 times 900 times 50 = 22,500 J.
4	12,600 J per degree	Heat capacity is m times c, so 3 times 4,200 gives 12,600 J per degree for the whole mass.
5	336 s	The energy needed is 168,000 J, and dividing by 500 W gives 336 s.
6	5,460 J	The fall is 70 degrees, so 0.2 times 390 times 70 gives 5,460 J released to the surroundings.
7	66.7 C	The energy is 1,000 times 420, or 420,000 J, and dividing by 6,300 gives 66.7 degrees.
8	56 C	Setting the heat lost by the hot water equal to the heat gained by the cold water gives 56 C.
9	2.1 times	For equal energy the rise is inversely proportional to specific heat capacity, so 4,200 over 2,000 gives 2.1.
10	A larger specific heat capacity means more energy per degree, so the rise is slower, not easier.	The student confuses storing more energy with rising faster; the two are inversely related.

04　What to do after marking

After marking, redo only the wrong items and write down which step went wrong (formula, unit, or misread number).
Repeat the same item two days later; move to the next paper only when both attempts are correct.
Parents only need the answer and note columns; there is no need to explain every item.

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