Temperature and heat (Thermal Energy)

What is heat?

(thermal energy) is the energy transferred between objects because of a difference in temperature

-based on vibrational energy of atoms

Heat will always flow from hot to cold according to the 2nd law of thermodynamics

What is temperature?

A measure of the average kinetic energy of the molecules of a substance.

Why does HEAT depend on mass?

The more heat required to raise a material's temperature by the same amount, the higher its specific heat. So, an object with more mass or higher specific heat will undergo a smaller temperature change than an object with less mass or lower specific heat.

Celsius

a temperature scale based on 0^o for the freezing point of water and 100^o for the boiling point of water

Kelvin

an absolute temperature scale that starts at the lowest possible temperature (absolute zero), taken to be 0 K.

How does Kelvin reflect the measurement of temperature more accurately?

Because it is an absolute scale, measurements made using the Kelvin scale do not have degrees. the base unit for temperature in the International System of Units (SI)

Why does the temperature of melting ice not change even though energy is being transferred as heat to the ice?

in phase changes, energy enters or leaves a system without causing a temperature change in the system. Since the energy that goes into performing the phase change goes into breaking intermolecular forces

The warm gulf air and cold arctic air colliding to form a tornado

Convection

Laying in a tanning bed

Radiation

Roasting hot dogs over a camp fire (hot dog not touching fire)

Convection and radiation

Making snow balls and your hands getting cold

Conduction

Internal energy can be changed two ways (1st law of thermodynamics)

Heat and Work

Law of Conservation of Energy

1st law of thermodynamics

Work done ON the system is _____ because internal energy increasing

positive

Work done BY the system is _____ because internal energy is decreasing

negative

The 2nd Law of Thermodynamics states that heat spontaneously flows from

Higher to low (hot to cold)

When does this flow stop?

When they reach equal temperature

In order for heat to flow from cold to hot, what must be done on the system?

Work

Cold to hot

Refrigerators, air conditioner, heat pumps

What is entropy?

The amount of disorder or chaos in a system

What does the 2nd law say about entropy?

A system tends toward greater disorder unless work is put into the system to change it. In other words, the entropy of all systems Increases unless work is done to decrease it.