"Rational Utilization of Mechanical Energy" Machinery and Human PPT Courseware 2

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"Rational Utilization of Mechanical Energy" Machinery and Human PPT Courseware 2

1. Understanding "can"

1. If an object can do work, we say it has energy.

2. The more work an object can do, the more energy it has.

3. Unit of energy: joule (J)

Do the following objects have energy? Divide the test into three categories and state the basis for classification.

1. Steel balls rolling on a horizontal track

2. The bent springboard

3. Chandeliers on the ceiling

4. The bent bow

5. A tight spring

6. The heavy hammer being lifted high

7. Football rolling on the ground

8. Books on the desk

9. Cars driving on level roads

1. Factors affecting the magnitude of kinetic energy and potential energy

1. Explore: What factors are related to the size of kinetic energy?

Conjecture: 1. The amount of kinetic energy is related to the speed of the object’s movement.

2. The amount of kinetic energy is related to the mass of the object

Design experimental plan:

Experiment 1: Explore the relationship between kinetic energy and speed

Summary conclusion:

When the mass is the same, an object with speed __ can do more work, indicating that it has kinetic energy __

Experiment: Explore the relationship between kinetic energy and mass

Comparing the two experiments on the right, we get:

When the speed is the same, an object with mass __ can do more work, which shows that it has kinetic energy __

Summarizing the above two sets of conclusions, we can draw:

The bigger the moving object is, the more kinetic energy it has.

conversion of mechanical energy

Energy cannot be created or destroyed out of thin air, it can only be converted from one form of energy into another form of energy.

Observe the whereabouts of the chalk

When the chalk falls, the speed is getting bigger and bigger, but the height is getting lower and lower. This shows that when the chalk falls, its kinetic energy becomes larger and larger, but its gravitational potential energy becomes smaller and smaller. In other words, the kinetic energy is increasing and the gravitational potential energy is decreasing, and the reduced gravitational potential energy is converted into kinetic energy.

1. The figure below is a schematic diagram of the experimental device for studying the relationship between the kinetic energy of the ball and the ____ and ____ of the ball. (1) The kinetic energy of the ball in this experiment is displayed by ____________________; (2) The table records the data of experiments conducted with two balls A and B respectively. It can be seen from the data in the table: the kinetic energy of ball A ______ (optional "greater than", "less than", or "equal to") the kinetic energy of ball B; (3) Among the two physical quantities of mass and speed, the kinetic energy has a greater impact It's _________.

2. Experimental questions

(1) Comparing the two experiments A and B in the figure, we can get:

When the mass is the same, the higher an object is lifted, the greater its gravitational potential energy.

(2) Comparing the two experiments _ and _ in the figure, we can get:

When the object is lifted to the same height, the greater the mass of the object, the greater the gravitational potential energy.

1. What form of mechanical energy does each of the following objects have?

(1). Football rolling on the ground

(2), a stone on the top of the mountain

(3) A bow bent on the ground

(4). Planes flying forward in the sky

2. The amount of kinetic energy is determined by the _____ and _____ of the object, and the amount of gravitational potential energy is determined by the ____________ and _____________ of the object.

3. Regarding the concept of energy, which of the following statements is correct ( )

A. Objects with equal potential energy must be at the same height

B. Since the hanging object does no work, it cannot

C. Bullets flying in the air have the ability to do work, so they have the ability to

D. If an object has mechanical energy, then the object must have both kinetic energy and potential energy.

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"Rational Utilization of Mechanical Energy" Machinery and Human PPT Courseware:

"Rational Utilization of Mechanical Energy" Machinery and Human PPT Courseware Review Review What is work? When a force acting on an object causes the object to pass a certain distance in the direction of the force, it is said that the force has done work on the object. Observation and Thinking Observation and Comparison: Think about small balls and heavy hammers..

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Update Time: 2024-11-22

This template belongs to Physics courseware Shanghai Science Edition 8th Grade Physics industry PPT template

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