3.4 
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Interactive Simulations   Interactive simulation of motion down an inclined plane    Motion down an inclined plane    Interactive simulation of an oscillating spring    Spring-loaded carts simulation    Elastic collisions between two balls    Inelastic collisions between two balls    Interactive simulation of an oscillating spring    Interactive simulation of an oscillating spring    Wind power design simulation Interactive Calculators   Work equation calculator    Kinetic energy equation    Potential energy equation    Elastic potential energy equation    Efficiency equation    Conservation of momentum in collisions equation    Power equation calculator
   Electric power equation    Temperature conversion equation    Specific heat equation
1 - Science of Physics
2 - Forces and Motion3 - Energy Transformations      Chapter 3 at a glance      3.1 - Energy      3.2 - Conservation of energy      3.3 - Flow of energy      3.4 - Temperature and the kinetic theory of matter      3.5 - Chapter review4 - Waves and Sound
5 - Electricity and Magnetism
6 - Light and Optics
7 - The Atom
8 - Linear Motion
9 - Vectors and Forces
10 - Forces
11 - Newton's Laws and Gravitation
12 - Circular Motion and Gravitation
13 - Torque and Static Equilibrium
14 - Momentum and Collisions
15 - Angular momentum
16 - Power and Machines
17 - Harmonic Motion
18 - Waves
19 - Sound
20 - Electricity
21 - Electric and Magnetic Fields
22 - Electromagnetism and Induction
23 - Light and Color
24 - Geometrical Optics
25 - Electromagnetic Radiation
26 - The Properties of Matter
27 - Thermodynamics and Heat Transfer
28 - The Atom
29 - The Quantum Theory
30 - TBD
31 - TBD
32 - TBD
33 - TBD
34 - TBD
35 - TBD
36 - TBD
37 - The atomic nucleus and radioactivity
38 - Nuclear reactions
39 - Relativity
40 - Particle physics and the standard model
41 - Electronics (semiconductors)
42 - Nuclear technology
43 - Lasers and photonics
44 - Metals, alloys and materials science
45 - Communications technology
46 - Buildings and structures
47 - Energy technology
48 - Biophysics
49 - Matter and Energy, Space and Time
50 - Energy Transformations
51 - Nanotechnology
52 - Website Videos
53 - ExtraStuff
55 - Modeling Motion, Friction, and Center of Mass
56 - Work and the Conservation of Energy
Heat
Difference between heat and temperature The difference between heat and temperature In everyday conversation we may use heat and temperature interchangeably, but in physics they are different. Boiling water in a teaspoon and boiling water filling a kitchen pot are both at the same temperature of 100°C. But the thermal energy content of the teaspoon is much smaller than that of the kitchen pot, because the pot contains much more boiling water. The pot's boiling water has more thermal energy, which gives it a much greater capacity to heat or burn you.
Units of thermal energy and heat Nutrition facts label for food Heat represents the flow of thermal energy from a hotter object to a colder one. More thermal energy can flow to you as heat from the water in the pot than from the water in the teaspoon. Since heat is the transfer of thermal energy, it is measured in the usual energy units of joules (J). Other units sometimes used to measure thermal energy are: the calorie, equal to 4.18 J; the kilocalorie (kcal) or Calorie (with an uppercase “C”!), equal to 1,000 calories; and the British thermal unit, equal to 1,055 J. Nutritional content labels on food provide the number of Calories—not calories—in the food. Show How many joules in a Calorie?
Heat and friction In nearly every transformation of energy, some is transformed to thermal energy due to friction—producing heat. A car is a technology designed to convert chemical energy in fuel into kinetic energy of motion. A liter of gasoline releases 35,000,000 joules of chemical energy when perfectly burned with oxygen. Most of this energy (65%) is converted to thermal energy that flows as heat out the radiator and tail pipe. Only 13% of the energy goes towards physically moving the car. While the thermal energy is not “lost,” it is not available to do mechanical work to move the car.
Explanation of heat and temperature What property of matter causes temperature? Answering this question took more than two thousand years! While the idea of temperature and even inventions such as thermometers and heat engines have been known since the time of ancient Greece, it remained a mystery until the 20th century exactly what temperature actually measures. We now know that temperature measures the average thermal energy per gram of matter. Likewise, absolute zero, the lowest possible temperature of matter, corresponds to the lowest possible thermal energy for atoms and molecules. Thermal energy comes from the microscopic motion of individual atoms and molecules within matter. If the atoms jostle around more vigorously, their energy of motion increases as does their temperature. A decrease in temperature corresponds to the atomic motion becoming more quiescent.
Test your knowledge Which of the following objects has the most thermal energy?
  1. Boiling water
  2. Ice
  3. Liquid nitrogen
  4. Unknown
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