Physical Sciences, Part 7

Question 1: Compare and contrast heat and temperature.

Answer 1: Heat is energy transfer (other than direct work) from one body or system to another due to thermal contact. Everything tends to become less organized and less orderly over time (entropy). In all energy transfers, therefore, the overall result is that the energy is spread out uniformly. This transfer of heat energy from hotter to cooler objects is accomplished by conduction, radiation, or convection. Temperature is considered a measurement of heat or heat energy. More specifically, temperature is the average kinetic energy of an object’s particles. When the temperature of an object increases and its atoms move faster, kinetic energy also increases. Temperature is not energy since it changes and is not conserved. Thermometers are used to measure temperature.

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Question 2: Define the following temperature and heat measurements: Celsius, Fahrenheit, Kelvin, and absolute zero. Provide relevant conversion formulas.

Answer 2: Celsius: Uses base reference points of water freezing at 0 degrees and boiling at 100 degrees.Fahrenheit: Uses base reference points of water freezing at 32 degrees and boiling at 212 degrees.Converting Celsius to Fahrenheit: C = 5/9 (F–32)Converting Fahrenheit to Celsius: F= (9/5) C+32Kelvin: These are the base SI units used to express thermodynamic temperature. Kelvin does not use degrees, but uses roughly the same scale as Celsius. The difference is that zero is a hypothetical absolute zero determined by the triple state of water. The triple state of water is 273.15 Kelvin, a measurement based on water that is in thermal equilibrium within a closed vessel.Converting Celsius to Kelvin: K = C + 273.15Converting Kelvin to Celsius: C = K – 273.15Absolute zero: Refers to the temperature at which no more energy can be transferred from a material.

Question 3: Define heat capacity and specific heat capacity. Relate each to heat and temperature change.

Answer 3: Heat capacity: Also known as thermal mass, heat capacity refers to the amount of heat energy it takes to raise the temperature of an object one degree, and is measured in Celsius or Kelvin. The equation for relating heat energy to heat capacity is Q = C?T, where “Q” represents the heat energy transferred, “C” is the heat capacity of the body, and “?T” refers to the change in temperature.Specific heat capacity: Also known as specific heat, specific heat capacity refers to the amount of heat energy it takes to raise or lower the temperature of an object with unit mass by one degree. For example, it takes different amounts of heat energy to raise the temperature of the same amounts of magnesium and lead by one degree. The equation for relating heat energy to specific heat capacity is Q =mc?T, where “Q” represents the heat energy transferred, “m” represents mass, “c” represents specific heat capacity, and “?T” represents the change in temperature.

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