"Gravity" PPT

Description

"Gravity" PPT

Part One: Introduction of New Course

All objects will fall to the ground when they lose support.

This is because the Earth has a gravitational pull on objects around it, pulling them toward the ground.

1. Gravity: The force exerted by an object due to the attraction of the earth is called gravity.

2. Understanding of gravity

(1) All objects near the ground are affected by gravity.

(2) The object exerting force by gravity is the earth. Objects subject to force: everything near the surface of the Earth

(3) Gravity is a non-contact force. Objects moving or stationary in the air will experience the same gravity as before.

(4) An object moving in the air is only affected by gravity if air resistance is not considered.

Gravity PPT, part 2: three elements of gravity

1. The size of gravity

1. The gravity exerted by an object can be measured using a spring dynamometer.

The amount of gravity exerted on an object is referred to as its weight.

Represented by G, unit: N

2. Explore the magnitude of gravity

(1) Ask questions

What factors are related to the magnitude of gravity?

(2) Make assumptions

Does the magnitude of gravity depend on the shape of the object?

Is the magnitude of gravity related to the mass of an object?

Does the magnitude of gravity depend on the position of the object?

(3) Design experiments:

Add 3 hook codes each with a mass of 50 g, increase one by one, hang them under the spring dynamometer, and record the readings.

(4) Conduct experiments:

Observe and record:

When one hook code, two hook codes, or three hook codes are hung at the lower end of the spring scale, the position of the spring scale pointer is located.

2. Direction of gravity

The direction of gravity points to the center of the earth

3. The point of action of gravity

The point where gravity acts on an object is called the center of gravity

The center of gravity of an object with regular shape and uniform mass distribution is at its geometric center

The center of gravity of a record with uniform quality and regular shape is at the center of its circle.

Gravity PPT, Part 3: Mass and gravity are two completely different concepts

1. Mass is the amount of matter contained in an object;

Gravity is the force on an object due to the attraction of the Earth

2. Mass only has size but no direction;

Gravity has both magnitude and direction.

3. The unit of mass is kilogram, and the measuring tool is a balance;

The unit of gravity is Newton, and the measuring tool is a spring balance.

4. The size of the mass does not change with the change of position;

The magnitude of gravity will change with geographical location.

Gravity PPT, Part 4: Class Summary

1. Definition of gravity:

The force on an object due to the attraction of the earth, symbol G

2. The size of gravity:

The gravitational force on an object is proportional to the mass of the object. That is G=mg

G — Gravity — Newton (N)

m — mass — kilogram (kg)

g — gravitational constant — 9.8 N/kg

3. Direction of gravity: always vertically downward

4. The point of action of gravity: at the center of gravity of the object

Gravity PPT, Part 5: Classroom Exercises

1. Among the following statements about the center of gravity, which one is correct ( )

A． The point where gravity acts on an object is called the center of gravity

B. The center of gravity of an object is affected by gravity

C. The center of gravity of a cone with uniform mass distribution is at the midpoint of its axis

D. The center of gravity of a sphere is always at the center of the sphere

2. Use a spring balance to weigh the small ball hanging at rest below it vertically, then we have ( )

A． The pulling force of the ball on the spring balance is the gravity of the ball

B. The pulling force of the ball on the spring balance is equal to the weight of the ball

C. The object exerting force on the ball by gravity is a spring

D. The object exerting the force of gravity on the small ball is the earth

3. If there is no gravity, which of the following statements is incorrect ( )

A. The river stopped flowing and the waterfall was no longer visible.

B. People leave the earth as soon as they jump up

C. The object will lose mass

D. The water in the cup cannot be poured into the mouth.

Keywords: Zhejiang Education Edition seventh grade science PPT courseware for the second volume free download, gravity PPT download, .PPT format;

For more information about the "Gravity" PPT courseware, please click the Gravity ppt tab.

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Update Time: 2024-09-08

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