Temperature

A measure of the average kinetic energy of the particles in an obect

An instrument that measures and indicates temperature

The temperature at which molecular energy is at a minimal (0 K on the Kelvin scale or -273.16 ^oC on the Celsius scale).

The energy transferred between objects that are at different temperatures; energy is always transferred from higher-temperature to lower-temperature objects.

(1.8 x Celsius temperature) + 32

T_F = 1.8t + 32

(Fahrenheit temperature -32)/1.8

t = (T_F - 32)/1.8

Celsius Temperature + 273

T = t + 273

Absolute zero is the temperature at which particles have minimal kinetic energy.

The higher temperature of the hot soup means that the water molecules in the soup will move faster on average than the water molecules in iced lemonade.

Predict whether a greater amount of energy will be transferred as heat between 1 kg of water and 10^oC and a freezer at -15^oC or between 1 kg of water at 60^oC and an oven at 65^oC.

More energy would be transferred between water at 10oC and a freezer at -15oC because the temperature difference is greater.

Determine which of the following has a higher temperature and which contains a larger amount of total kinetic energy: a cup of boiling water or Lake Michigan.

A cup of boiling water has a higher temperature than Lake Michigan, but Lake Michigan has more total kinetic energy since it has more particles.

Convert the temperature of the air in an air-conditioned room, 20.0^oC, to equivalent values on the Fahrenheit and Kelvin temperature scales.

1.8 (20.0) + 32 = 68^oF

20 + 273 = 293^oK

Convert the coldest outdoor temperature ever recorded, -128.6^oF, to equivalent Celsius and Kelvin temperatures.

(-128.6^oF -32)/1.8 = -89.2^oC

-89.2^oC + 273 = 184^oK

The transfer of energy as heat through a material.

The movement of matter due to differences in density that are caused by temperature variations; can result in the transfer of energy as heat.

The vertical movement of air currents due to temperature variations.

The energy that is transferred as electromagnetic waves, such as visible light and infrared waves.

The quantity of heat required to raise a unit mass of homogeneous material 1 K or 1^oC in a specified way given constant pressure and volume.

energy = (specific heat) x (mass) x (temperature change)

energy = cmΔt

How much energy must be transferred as heat to the 420 kg of water in a bathtub in order to raise the water's temperature from 25^oC to 37^oC?

Given Δt = 37^oC -25^oC = Δ12 K

Δt  = 12 K

m = 420 kg

c = 4186 J/kg •K

energy = (4186 J/kg •K) x (420 kg) x (12 K)

energy = 21000000 J = 2.1 x 10⁴ kJ

A machine that transforms heat into mechanical energy, or work.

The first law of thermodynamics states that energy can be transformed, i.e. changed from one form to another, but cannot be created or destroyed. It is usually formulated by stating that the change in the internal energy of a system is equal to the amount of heat supplied to the system, minus the amount of work performed by the system on its surroundings.

The Second Law of Thermodynamics is commonly known as the Law of Increased Entropy. While quantity remains the same (First Law), the quality of matter/energy deteriorates gradually over time. How so? Usable energy is inevitably used for productivity, growth and repair. In the process, usable energy is converted into unusable energy. Thus, usable energy is irretrievably lost in the form of unusable energy.

"Entropy" is defined as a measure of unusable energy within a closed or isolated system (the universe for example). As usable energy decreases and unusable energy increases, "entropy" increases. Entropy is also a gauge of randomness or chaos within a closed system. As usable energy is irretrievably lost, disorganization, randomness and chaos increase.

The third law of thermodynamics concerns the entropy of a perfect crystal at absolute zero temperature, and implies that it is impossible to cool a system to exactly absolute zero, or, equivalently, that perpetual motion machines of the third kind are impossible.