Physics · Thermodynamics

Heat Transfer

Simulation loading

Open Model Lab is preparing the live lab, controls, and graph surface for this concept.

Wrap-up

What you learned

Recommended next: Open concept testCheck whether the core ideas are ready without leaving this concept.
Read next: Specific Heat and Phase ChangeFollow the transferred energy and ask what it does to temperature or phase.

Key takeaway

Heat is energy crossing a boundary because a temperature difference exists.
The total rate is built from conduction, convection, and radiation rather than from one hidden heat pathway.
Contact quality and material conductivity mainly change conduction, while airflow mainly changes convection.
Large temperature contrast can make radiation more important, especially when contact and airflow are weak.

Common misconception

Do not say a hot object contains heat. Say it contains internal energy, and heat is the transfer that occurs when surroundings are at a different temperature.

A hot object contains internal energy, but heat is the energy crossing into or out of it because of a temperature difference.

Keep this idea moving

Open the next concept, route, or track only when you want the current model to widen into a larger branch.

What the energy does nextThermodynamics

Specific Heat and Phase Change

See why the same energy pulse changes different materials by different temperature amounts, and why a phase-change shelf can absorb or release energy without changing temperature on one compact thermal bench.

Energy bookkeepingThermodynamics

Temperature and Internal Energy

Compare average particle motion with whole-sample energy, vary amount and heating, and see why a phase-change shelf breaks naive temperature-only reasoning on one compact thermal bench.

Gas-state contrastThermodynamics

Ideal Gas Law and Kinetic Theory

Connect pressure, volume, temperature, and particle number on one bounded particle box, then read the same pressure changes back as changes in particle speed and wall-collision rate.

Stay with this concept

Review, test, or free-play here when you want one more same-concept pass.

More practice optionsReview on the bench · Worked examples

Practice optionReview on the benchReplay the guided setup with the key controls and graphs in sight.
Practice optionWorked examplesCompare against solved walkthroughs after you try the setup yourself.
Practice optionFree play on the benchExperiment freely with the live controls before moving to another concept.

Reference and support

Use these calmer sections when you want a fuller explanation, examples, or accessibility support after the guided flow.

Return here when you want the slower reference pass.

Open reference and support

Equation snapshotTotal heat-transfer rate · Conduction trendShow 3 equations

Use total rate to keep the three pathways together, then compare the contact-driven conduction trend with the high-contrast radiation trend.

Total heat-transfer rate
$\overset{q}{˙}_{total} = \overset{q}{˙}_{cond} + \overset{q}{˙}_{conv} + \overset{q}{˙}_{rad}$
On this bench, the outward heat-transfer rate is the sum of the three visible pathways.
Conduction trend
$\overset{q}{˙}_{cond} \propto k_{mat} χ A (T_{hot} - T_{room})$
Conduction grows with material conductivity, contact quality, shared area, and temperature difference.
Radiation trend
$\overset{q}{˙}_{rad} \propto ε A (T_{hot}^{4} - T_{room}^{4})$
Radiation works without contact and grows especially quickly at large temperature contrast.

Why it behaves this way

Explanation

On this bench, heat means energy crossing from the hotter block to the cooler surroundings. The block stores internal energy, but heat is the transfer itself, so both the direction and the rate come back to the temperature difference.

The same hot block can lose energy through three pathways at once. Conduction uses the solid contact with the bench, convection uses moving air, and radiation uses thermal emission that still works even without solid contact.

Watch how the pathways change as the block cools. The temperature gap shrinks, so the pathway rates usually shrink too. This page is about identifying where the energy goes before later topics ask how that transfer changes temperature.

Key ideas

01Heat is energy transfer caused by a temperature difference, not energy stored inside the block.

02Conduction gets stronger when the material is more conductive, the contact is better, the shared area is larger, or the temperature difference is larger.

03Convection depends on moving air and exposed area, so stronger airflow can increase transfer without changing the solid-contact path.

04Radiation needs no contact and becomes much more important at large temperature contrast.

Worked examples

Open examples when you want to see the same idea walked through step by step.

Frozen walkthrough

Step through the frozen example

Frozen walkthrough

Use the live block, room, and pathway readouts as your evidence. Each calculation should match what you see in the pathway bars and graphs.

Supporter unlocks saved study tools, exact-state sharing, and the richer review surfaces that support this guided flow.

View plans

Example 1 of 2

Frozen valuesUsing frozen parameters

For the current setup, what temperature difference is driving the transfer, and how much of the total rate comes from conduction, convection, and radiation right now?

T_{hot}

Hot-block temperature

150 degC

T_{room}

Room temperature

25 degC

Δ T

Temperature contrast

125 degC

\overset{q}{˙}_{total}

Total transfer rate

63.9 u/s

1. Read the temperature gap

The block is at

T_{hot} = 150 degC

while the room is

T_{room} = 25 degC

, so the current contrast is

Δ T = 125 degC

2. Read the three pathway rates

Right now the live rates are

\overset{q}{˙}_{cond} = 43.74 u/s

\overset{q}{˙}_{conv} = 13.5 u/s

, and

\overset{q}{˙}_{rad} = 6.66 u/s

3. Add them to get the total

Adding the three visible pathways gives a total transfer rate of

\overset{q}{˙}_{total} = 63.9 u/s

Current split of the total rate

\overset{q}{˙}_{cond} = 43.74 u/s, \overset{q}{˙}_{conv} = 13.5 u/s, \overset{q}{˙}_{rad} = 6.66 u/s

Conduction is dominant here because the material-contact path is strong while the room stays cooler than the block.

Quick test

Loading saved test state.

Accessibility

Open the text-first descriptions when you need the simulation and graph translated into words.

The simulation shows a hot block beside a cooler bench and room. A temperature-gap bridge, a solid contact channel, airflow cues, and radiation arcs all come from the same hot-block and room temperatures.

Changing the controls updates one shared heat-flow state. The temperatures, pathway split, readout card, graphs, prediction mode, compare mode, and challenge checks all stay synchronized.

Graph summary

The temperature-history graph compares the hot block with the fixed room temperature so the shrinking temperature gap stays visible. The pathway-rates graph compares conduction, convection, radiation, and the total on one shared time axis.

The contact-response graph changes only contact quality, so it isolates conduction. The contrast-response graph changes only temperature contrast, which is where the stronger upward bend of radiation is easiest to see.

Bench tools and share links

Keep stable concept links and exact-state sharing tucked away until you actually need to relaunch or share the bench.

Try this setup

Jump to a named bench state or copy the one you are looking at now. Shared links reopen the same controls, graph, overlays, and compare context.

Current bench

Metal on cool bench preset

This bench is currently showing one of the concept's authored presets.

Open default bench

Saved setups

Saved setups are a Supporter study tool. Stable concept links still work for everyone.

Checking saved setup access

Open Model Lab is resolving whether this bench can save locally, sync to an account, or open Supporter-only compare tools.

Copy current setup

Exact-state sharing is part of Supporter. Stable concept and section links still stay available.

Stable links

Progress and next steps

Keep progress signals, starter-track handoffs, and review prompts available without letting them compete with the live lesson flow.

Progress

Loading progress

Loading saved concept progress for this browser or synced account before showing completion status.

Starter track

Step 3 of 4

Thermodynamics and Kinetic Theory

Heat Transfer appears later in this track, so it is cleaner to start from the beginning first.

Previous step: Ideal Gas Law and Kinetic Theory

Start from track beginning