"Internal Energy and Its Changes" Heat and Energy PPT Courseware 2

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"Internal Energy and Its Changes" Heat and Energy PPT Courseware 2

Internal energy

The sum of the kinetic energy of thermal motion and molecular potential energy of all molecules inside an object. The unit of internal energy is Joule (J).

A moving football has kinetic energy;

Molecules in motion also have kinetic energy.

A spring has potential energy when it is stretched or compressed;

There are attraction and repulsion forces between molecules, as well as potential energy.

All objects, regardless of temperature, have molecules in motion and therefore have internal energy.

For the same substance, the higher the temperature, the faster the molecules move.

The greater the mass, the greater the number of molecules and therefore the greater the internal energy.

The same substance has the same temperature, the same mass, different states, and different internal energies.

Thinking: Among ice, water, and water vapor with equal masses and the same temperature, which one has the greater internal energy?

think

How do you increase the temperature of a 50 cm section of wire?

1. Heating with flame 2. Sunbathing

3. Rub with hands 4. Heat with hands

5. Rub it on the ground 6. Hit it with a hammer

7. Repeatedly bending 8. ……

Divide these methods into two categories. What are your principles for classification?

How do you increase the temperature of a 50 cm section of wire?

Divide these methods into two categories. What are your principles for classification?

changes in internal energy

heat transfer:

transfer of internal energy.

The amount of internal energy transferred is called heat. Unit: J.

When heat is absorbed, internal energy increases; when heat is released, internal energy decreases.

acting:

The mutual conversion of mechanical energy and internal energy;

When work is done on an object, the internal energy of the object increases;

When an object does work on the outside, its internal energy decreases.

Practice in class

1. During the experiment of "pumping air into a bottle containing a small amount of water", the teacher kept pumping air into the bottle, so that the pressure of the water vapor in the bottle increased, and the internal energy of the water vapor _______ (fill in "increase" or "reduce"), temperature ________ (fill in "increase" or "decrease").

When the cork jumps up, you can see _______ inside the bottle. This is because the water vapor _______ the cork, and the internal energy _______ (fill in "increase" or "less"). Temperature_______ (fill in “increase” or “decrease”). Water vapor _______ into small droplets. When the white mist does not disappear, if you immediately close the stopper and pump air into the bottle again, you will see _______.

2. Among the following options, the change in the internal energy of an object is achieved through work ( )

A. On a hot summer day, put some ice cubes in your beer and it will become cooler

B． The water in the solar water heater tank is heated by the sun

C. When a car is running, the tires get hot

D． Strike a match, burn a match

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For more information about the PPT courseware "Heat and Energy Internal Energy and Its Changes", please click the Heat and Energy ppt Internal Energy and its Changes ppt tab.

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Update Time: 2024-11-24

This template belongs to Physics courseware Lu Jiao Edition Ninth Grade Physics Volume 2 industry PPT template

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