"Mechanical Energy and Its Transformation" Work and Mechanical Energy PPT Courseware 4

Description

"Mechanical Energy and Its Transformation" Work and Mechanical Energy PPT Courseware 4

teaching objectives

1. Know the conversion of kinetic energy and gravitational potential energy. Give an example of the conversion of kinetic energy and gravitational potential energy.

2. Know the conversion of kinetic energy and elastic potential energy, and be able to give examples of the conversion of kinetic energy and elastic potential energy.

3. Analyze and explain examples to illustrate the conversion process of kinetic energy and potential energy, and the changes of kinetic energy, potential energy and mechanical energy.

Conclusion: Kinetic energy and gravitational potential energy can be converted into each other.

1. Ascent: speed _____, height _____, kinetic energy _____,

Gravitational potential energy _____, _____ energy is converted into _____ energy.

2. Descent: speed _____, height _____, kinetic energy _____,

Gravitational potential energy _____, _____ energy is converted into _____ energy.

2. Conversion of kinetic energy and elastic potential energy

When the bow is drawn and the arrow is shot out, the bow's elastic potential energy _____, the arrow's kinetic energy _____, and the bow's _____ energy is converted into the arrow's _____.

1. Mechanical energy:

Kinetic energy and potential energy are collectively called mechanical energy.

1. Mechanical energy = kinetic energy + potential energy

2. Kinetic energy is the energy an object has when it moves.

3. Potential energy is stored energy.

practice

Analyze the energy transformation in the process of the ball falling and bouncing from the hand.

When the ball falls to the ground, _______ energy is converted into ___ energy; when it hits the floor, _______ energy is converted into _______ energy; when it recovers its deformation (without leaving the ground) and bounces upward, _______ is converted into _______ energy , when bouncing upward from the ground, energy is converted into _______ energy.

1. The spring door can close itself after being pushed open. This process will be explained from the transformation of energy.

When the spring door is pushed open, the kinetic energy is converted into elastic potential energy; when the spring door is automatically closed, the elastic potential energy is converted into kinetic energy

2. The picture below shows the design plan of a certain city’s subway. The incoming and outgoing tracks form a gentle slope with the platform. In order to make full use of energy, the train turns off the engine before entering the station and goes up the slope. Due to the inertia, it rushes up the gentle slope and then goes up the slope. When the train's kinetic energy gradually increases, its gravitational potential energy gradually increases.

(Optional "Increase", "Decrease" or "No change")

1. After a skydiver jumps from an airplane in the sky, during the fall before the parachute opens, the athlete’s ( )

A. Kinetic energy increases and gravitational potential energy decreases

B. Kinetic energy decreases and gravitational potential energy increases

C. Kinetic energy decreases and gravitational potential energy decreases

D. Kinetic energy increases and gravitational potential energy increases

2. When an object is acted upon by a pair of balancing forces, its ( )

A. Kinetic energy remains unchanged

B. Kinetic energy may increase or decrease

C. Gravitational potential energy must decrease

D. Gravitational potential energy must increase

3. As shown in the figure, the ball successively starts from rest and slides from the top to the bottom from the smooth inclined plane with the inclination angles of 30° and 60° respectively. The speed when it slides to the bottom is v1 and v2 respectively. Then the following relationship is: the correct one is( )

A. v1>v2 B. v1=v2

C. v1＜v2 D. Unable to determine

Have you ever paid attention to physics in life?

The spring door can close by itself after being pushed open. This is because after the door is pushed open, the spring is tightened and deformed, and has _______ energy. When it is let go, it is converted into the _____ energy of the door, causing the door to close automatically.

practise:

1. When a skydiver falls in the air at a constant speed, gravitational potential energy _____, kinetic energy _____, and mechanical energy _____.

2. When Xiao Ming was sliding down the smooth slide, which of the following statements was correct? Disregarding air resistance ( )

A. Gravitational potential energy decreases, kinetic energy increases, and mechanical energy remains unchanged.

B. Gravitational potential energy increases, kinetic energy decreases, and mechanical energy remains unchanged.

C. Gravitational potential energy increases, kinetic energy remains unchanged, and mechanical energy increases.

D. Gravitational potential energy decreases, kinetic energy remains unchanged, and mechanical energy decreases.

Have you ever paid attention to physics in life?

When our classmates come to school, they often have to pedal harder before going uphill; car drivers often have to increase the accelerator and speed before driving uphill.

Explain the benefits of this from the perspective of energy conversion.

Pedal a few times before going uphill to increase the speed of the bicycle and increase the kinetic energy. More kinetic energy can be converted into gravitational potential energy, making it easier for the actual bike to go uphill.

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For more information about the PPT courseware "Mechanical Energy and Its Transformation into Work and Mechanical Energy", please click on the Mechanical Energy and Its Transformation ppt Work and Mechanical Energy ppt tag.

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Update Time: 2024-12-11

This template belongs to Physics courseware People's Education Edition Physics for Grade 8, Volume 2 industry PPT template

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