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Thermal Energy

Thermal Energy. Section 1: Temperature and Heat. Kinetic Theory. All matter is made of tiny particles (atoms and/or molecules). All particles (atoms and molecules) are always in motion. At the same temperature, smaller particles will move faster than larger particles.

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Thermal Energy

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  1. Thermal Energy Section 1: Temperature and Heat

  2. Kinetic Theory • All matter is made of tiny particles (atoms and/or molecules). • All particles (atoms and molecules) are always in motion. • At the same temperature, smaller particles will move faster than larger particles.

  3. Kinetic Energy and Temperature • Temperature is related to the average kinetic energy of an object’s atoms or molecules. • The faster the particles move, the higher the temperature!

  4. States of Matter and Temperature • Solids • Particles moving slow (vibrating in place) • Temperature is low • Liquids • Particles moving a little faster (able to move past each other) • Temperature is higher • Gases • Particles are moving very fast • Temperature is very high

  5. Thermal Energy • Thermal energy is the sum of the kinetic and potential energy of all the atoms in an object. • Thermal energy increases as temperature increases. • At a constant temperature, thermal energy increases if mass increases.

  6. Energy as Heat • Thermal energy that flows from something at a higher temperature to something at a lower temperature is called heat. • Heat is the flow of thermal energy.

  7. How much heat is needed? • Specific heat is the measure of the amount of heat needed to raise the temperature of 1 kg of a material by 1 degree Celsius or Kelvin. • Water = 4,184 Joules • Iron = 450 Joules

  8. Changes in Heat • Changes in thermal energy can be calculated as change in thermal energy equals mass times change in temperature times specific heat. Energy Change = (TF - TI) x mass x specific heat

  9. Change in Thermal Energy • When heat flows into an object and raises its temperature, the change in temperature is positive.

  10. Change in Thermal Energy • When heat flows out of an object and its temperature decreases, the change in temperature is negative. • A calorimeter is a device used to measure specific heat.

  11. Changes in Thermal energy Q = m × ΔT × C ** Δ= change** Q = m × (TF – TI) × C

  12. Changes in TE #1 • The human body has a specific heat of approximately 3470 J/(kg°C). Hypothermia can occur if the body temperature drops to 35.0°C, although people have been known to survive much lower temperatures. On January 19, 1985, 2-year-old Michael Trode was found in the snow near his Milwaukee home with a body temperature of 16.0°C. If Michael's mass was 10.0 kg, how much heat did his body lose, assuming his normal body temperature was 37.0°C? (Happily, Michael survived!) Q = (TF – TI) × m × C = (16-37) × 10.0 × 3470 = -728,700 Joules

  13. Changes in TE #2 • The specific heat of air is 1011 J/(kg °C). If there is 0.002 kg of air in the room, what amount of energy must be added to raise the temperature of the classroom from 19°C to 23°C? Q = (TF – TI) × m × C = (23-19) × 0.002 kg × 1011 Q = 8.088J

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