# The container on the left is cooler, the molecules move slower (have less kinetic energy) and exert a smaller pressure on the container walls compared.

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The container on the left is cooler, the molecules move slower (have less kinetic energy) and exert a smaller pressure on the container walls compared.

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The container on the left is cooler, the molecules move slower (have less kinetic energy) and exert a smaller pressure on the container walls compared to the molecules of the warmer container at right.

Boiling: 100 oC 373 K 212 oF Freezing: 0 oC 273 K 32 oF A temperature change of 1oC is the same as a temperature change of 1 K. Both of these are equal to a temperature change of 1.8 oF.

1 calorie is the amount of heat energy needed to raise 1
1 calorie is the amount of heat energy needed to raise 1.0 gram of water by 1.0 oC. 1.0 calorie = 4.2 Joules A 100 W light bulb uses energy at a rate of 100 J/s.

1 calories is the amount of heat energy needed to raise 1
1 calories is the amount of heat energy needed to raise 1.0 gram of water by 1.0 oC. How much energy is need to raise 10 gm of water by oC? How much energy is need to raise 5 gm of water by oC? How much energy is need to raise 5 gm of water by oC?

How much energy is need to raise 10 gm of water by 1.0 oC? 10 calories
The heat capacity of an object is the total amount of heat energy needed to raise the temperature of an object by 1.0 oC The heat capacity of the ocean is huge and the heat capacity of a cup of coffee is small. The heat capacity of 10 gm of water is 10 calories/oC and that of 5 grams of water is 5 calorie/oC. Heat capacity is also called thermal inertia as it describes how hard it is to change an object’s temperature.

States of Matter 1. Gas 2. Liquid 3. Solid

Molecules of a gas have a high average energy compared to molecules of a liquid or solid.

Molecules of a liquid have an intermediate average energy compared to molecules of a gas or solid.

Molecules of a soli have the lowest average energy compared to molecules of a liquid or gas.

It takes energy to convert ice into liquid water
It takes energy to convert ice into liquid water. That is it takes energy to melt ice. As ice in an ice water mixture melts the temperature doesn’t change. All of the energy going into the ice water id used to change ice into water. This energy is referred to as latent heat energy. Latent means hidden .

When water evaporates from your body, energy is removed from or added to the water?
When water evaporates from your body, energy is removed from or added to your body? When water freezes energy is removed from or added to the water?

When water evaporates from your body, energy is removed from or added to the water?
When water evaporates from your body, energy is removed from or added to your body? When water freezes energy is removed from or added to the water?

The energy released into the environment as clouds form causes the air to warm which further enhance the vertical growth of clouds.

3 mechanisms for Heat Transfer

Conduction: The energetic hot molecules collide with less energetic cooler molecules transferring energy fro hot to cold via molecular collisions.

Conduction through a wall, window, or slab of ice on a lake or ocean.

Relative Thermal Conductivities
Silver 420 Aluminum 240 Water Snow Ice Wood Vacuum

Convection is the transfer of energy from hot to cold via the net flow of warm fluid (liquid or gas). In meteorology vertical air motion and heat transfer it referred to as convection and horizontal flow is advection.

Thermal convection developing in the afternoon cools the ground and warms the air above.

As air rises it expands because the pressure it feel gets smaller and smaller. Expanding air naturally cools. Try this! Open your mouth fairly wide and gently blow air onto your hand. It will likely feel warm. Now pucker and blow air rapidly onto you hand through a small opening in your mouth. It should feel a bit cooler.

The freezer compartment becomes very cold as the refrigeration fluid escapes through the expansion valve.

As air sinks it is compressed because the pressure it feel gets greater and greater. Compressed air naturally warms. Try this! Feel the bottom of your bicycle pump after you have been pumping air into your tire.

As the air filled tube is compressed the tissue paper ignites.
In a diesel engine as the air fuel mixture is compressed rapidly it ignites. No need for spark plugs, rapid compression is enough to keep the engine running.

Expanding (rising) air cools Compressing (sinking) air warms

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