Grade 7 Β· Unit 3 Β· Heat Transfer

Hot is not
Heat.

🏊 A swimming pool vs β˜• a cup of coffee β€” which one has MORE heat?
The coffee is hotter. The pool is cooler. But they are not the same thing. Think carefully before scrolling β€” your answer might surprise you.
E2 Β· Explore

Temperature vs Heat

No definitions yet. Drag the slider and watch the two mystery quantities. One measures something per particle. The other counts all the particles. Can you figure out the difference?

Choose your substance

Mystery A (per particle)80Β°

Live comparison

80Β°C
Mystery A
240 J
Mystery B
80Β°C
Temperature
240 J
Total Heat
Particle speed = temperature Β· Number of particles = total heat capacity
E3 Β· Explain

The Science of Heat

Now the formal names for what you discovered. Keep this open while solving problems.

Temperature
T (Β°C or K)
Average kinetic energy per particle. Measured with a thermometer. Does NOT depend on amount of substance.
Heat (Thermal Energy)
Q = mcΞ”T
Q = heat (J) Β· m = mass (kg) Β· c = specific heat Β· Ξ”T = temp change
Conduction
contact β†’
Heat transfers through direct particle contact. Needs a solid medium. Best in metals.
Convection
↑ hot ↓ cold
Heat transfers through fluid movement. Hot fluid rises, cold sinks. Needs liquid or gas.
Radiation
∿∿∿ β†’
Heat transfers as electromagnetic waves. Needs NO medium. Works in vacuum (space!).
The Key Difference
T β‰  Q
High temperature β‰  high heat. A spark is hotter than a pool but has far less total thermal energy.
πŸ’‘ Answer to the opening question:

The swimming pool has more heat! Even though the coffee is hotter (higher temperature), the pool contains billions more water molecules. Total thermal energy (heat) = temperature Γ— mass Γ— specific heat. The pool wins because of its enormous mass.

E3 Β· Transfer Methods

3 Ways Heat Travels

Every transfer of heat in the universe happens through one of these three methods. Click each to see the live simulation.

Conduction

Heat travels through direct contact between particles. Faster-moving (hot) particles collide with slower (cold) neighbours and pass on kinetic energy β€” like a line of dominoes.

Needs medium
Must have solid/liquid contact
Best in metals
Free electrons carry energy fast
Real examples
πŸ₯„
Metal spoon in hot soup
Handle gets hot through direct contact
🍳
Frying pan on stove
Heat conducts from burner through metal
🧊
Ice cube in your hand
Heat conducts from hand to ice β€” hand feels cold
Ahmad's Note: "Conductors pass energy on freely β€” like a good teacher passing knowledge through direct connection."
Live simulation β€” Conduction
Hot end (left) particles vibrate fast β†’ collide with neighbours β†’ energy passes right β†’
Watch the colour shift from red (hot) to blue (cool) as heat conducts through the rod.
Conduction Convection Radiation
Needs medium? Yes (solid) Yes (fluid) No!
Particles move? Vibrate only Flow in loops No particles
Example Metal spoon Boiling water Sunlight
✦ Quick check β€” identify the transfer method
E4 Β· Elaborate

Apply & Challenge

Each problem shows a live scenario. Study it, then answer. One question is a misconception trap β€” think carefully!

Problem 01 Β· Multiple Choice
A metal spoon is placed in a hot bowl of soup. After 2 minutes, the handle feels warm. How did the heat travel to the handle?
AConvection β€” hot soup rose up the spoon
BConduction β€” particles passed energy through direct contact
CRadiation β€” heat waves travelled through air to the handle
DConvection β€” hot air rose around the spoon
Problem 02 Β· Multiple Choice
The sun warms the Earth from 150 million kilometres away through the vacuum of space. Which method of heat transfer makes this possible?
AConduction β€” through space particles
BConvection β€” through solar wind currents
CRadiation β€” electromagnetic waves need no medium
DConduction and Convection combined
⚠ Misconception Trap
Problem 03 Β· True or False β€” Think carefully!
You open a refrigerator and feel cold air coming out. "Cold is travelling from the fridge into the room." Is this statement correct?
ATrue β€” cold travels just like heat does
BFalse β€” heat travels FROM the room INTO the fridge, not the other way
Problem 04 Β· Fill in the blank
A pot of water is placed on a stove. The water at the bottom heats first, rises, and the cooler water sinks to be heated. This process is called __________.
AConduction
BConvection
CRadiation
Bonus Β· Open Question Β· AI Tutor
A thermos flask keeps hot drinks hot and cold drinks cold. It has a vacuum between its walls and shiny silver surfaces inside. Explain how the thermos flask reduces each of the three types of heat transfer. Use conduction, convection, and radiation in your answer.
E5 Β· Evaluate

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