"Internal Energy and Its Changes" Heat and Energy PPT Courseware 3

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"Internal Energy and Its Changes" Heat and Energy PPT Courseware 3

Molecules have kinetic and potential energy

The molecules that make up matter are constantly undergoing thermal motion and also have kinetic energy, and the interaction between molecules gives them potential energy.

1. Internal energy of an object

1. The sum of the kinetic energy of thermal motion and molecular potential energy of all molecules inside an object is called the internal energy of the object.

2. The unit of internal energy is Joule (J)

3. Mechanical energy is related to the mechanical motion of the entire object, and internal energy is related to the thermal motion of the molecules inside the object and the interaction between molecules, so internal energy is another form of energy different from mechanical energy.

Because the molecules of all objects are constantly moving irregularly, all objects have internal energy.

The amount of internal energy of an object is related to temperature, mass, and state of matter

Decide whether the following statements are correct

1. Objects with high temperature have internal energy, while objects with low temperature do not have internal energy ( )

2. An object with a high temperature must have more internal energy than an object with a low temperature ( )

3. Water at 0°C turns into ice at 0°C. The temperature remains unchanged, so the internal energy remains unchanged ( )

4. When the temperature of an object decreases, the internal energy decreases; when the temperature increases, the internal energy increases.

Heat transfer can change the internal energy of an object

1. When heat transfer occurs, high-temperature objects release heat and their internal energy decreases; low-temperature objects absorb heat and their internal energy increases.

2. In the process of heat transfer, the amount of internal energy transferred is called heat, and the unit of heat is Joule.

3. Conditions for heat transfer to occur: there is a temperature difference

The internal energy of an object increases when it absorbs heat and decreases when it releases heat.

The more heat it absorbs or releases, the greater its internal energy changes.

The essence of heat transfer:

Internal energy is transferred from one object to another.

2. Changes in the internal energy of an object

1. The internal energy of an object decreases when its temperature decreases, and increases when its temperature increases.

2. How to change the internal energy of an object

Heat transfer and work are equivalent in changing the internal energy of an object

When an object absorbs heat, its temperature must rise. ×

When an object emits heat, its temperature must decrease ×

The temperature of an object increases because it must have absorbed heat ×

When the temperature of an object decreases, heat must be released ×

If the temperature of the object remains constant, there will be no heat absorption or heat release ×

As the temperature of an object increases, the internal energy must increase√

When the temperature of an object decreases, the internal energy must decrease√

As the internal energy of an object increases, the temperature must increase ×

As the energy in an object decreases, the temperature must decrease ×

When work is done on an object, the temperature of the object must increase ×

Try your hand

1. As the temperature of an object increases, the thermal motion of its internal molecules becomes ____, and its internal energy becomes ____. The unit of internal energy is ______.

2. The condition for heat transfer between contacting objects is __________.

3. When the internal energy of an object increases, the object may ______ heat, or the outside world may _____ the object.

4. The internal energy of an object refers to ( ).

A. The energy possessed by an object to make mechanical motion

B. The energy possessed by the movement of individual molecules in an object

C. The energy of directional movement of molecules within an object

D. The sum of the energy of all molecules in an object that move randomly

5. In the following process, the energy in the object is increased by means of heat transfer ( ).

A. Rub your hands vigorously in winter to keep them warm

B. "Blow" on your hands to keep them warm in winter

C. When an iron spoon is placed in hot soup, even the handle will soon become hot to the touch.

D. In summer, when a beer bottle is suddenly opened, "white gas" will appear at the mouth of the bottle.

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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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"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 Main Contents of Molecular Kinetic Theory 1. Matter is composed of molecules 2. The molecules of all substances are constantly making irregular motion (thermal motion) 3. There is mutual interaction between molecules Definition of the internal energy of an object due to the gravitational and repulsive forces acting on it..

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Update Time: 2024-08-01

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

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