"Gravity" force PPT courseware 2

Description

"Gravity" force PPT courseware 2

1. How gravity is generated

1. Definition: The force exerted on objects near the ground due to the attraction of the earth.

2. Symbol: G

3. Force: Earth

4. Unit: Newton (N)

Ask students to discuss:

What would happen if the gravity on objects on Earth suddenly disappeared? Please imagine three scenarios and discuss them with your classmates.

For example:

People cannot drink water into their stomachs

Those who hang in the air will not fall;

The water will not go lower;

A person can fly into space at a constant speed by simply pushing on the ground;

Launching an artificial earth satellite does not require a rocket with huge thrust, but it will not orbit the earth...

2. Explore what factors are related to the size of gravity

1. Conjecture: What is the relationship between the gravity on an object and its mass?

Conjecture: The greater the mass, the harder it is to lift the object, so the greater the mass, the greater the gravity.

2. Design experiments

Use a spring dynamometer to measure the gravity of different hook sizes, as shown in the picture on the right.

Inductive improvement:

2. The size of gravity

1. The gravity exerted on an object is proportional to the mass of the object

2. G=mg where g=9.8N/kg

The meaning is: an object with a mass of 1kg near the ground experiences a gravity of 9.8N

1. The force exerted on objects near the ground due to ______ is called gravity. ______ objects on Earth are affected by gravity.

2. The object exerting force by gravity is: .

3. The gravity of an object is ___ proportional to its mass, the formula is ______, g=______

4. Students, your mass is ______kg, and your gravity is ______ (g=10N/kg)

Do the math:

An object weighs 4.9N measured using a spring dynamometer. What is the mass of the object in grams?

Known: G=4.9N g=9.8N/Kg

Request: m

Solution: From G=mg

m=G/g=4.9N/9.8N/Kg=0.5kg=500g

Answer: The mass of the object is 500g.

Class summary

1. Gravity: There is a mutual attraction force between any two objects in the universe, from as large as celestial bodies to as small as dust.

2. Gravity: the force exerted on an object due to the attraction of the earth, symbol G

3. The magnitude of gravity: The gravity experienced by an object is proportional to the mass of the object.

G=m g G—Gravity—Newton (N)

m—mass—kilogram (kg)

4. Direction of gravity: vertically downward

5. The point of action of gravity: center of gravity

practise

1. The force exerted on an object due to ________ is called gravity, and its magnitude can be measured by ________. In daily life, the amount of gravity exerted by an object is referred to as ________.

2. Among the following statements, which one is wrong ( )

A. The instruments used to measure gravity are different from those used to measure mass.

B. The gravity exerted by an object at the same place is proportional to the amount of matter it contains.

C. The same object on the earth and the moon respectively has the same mass but changes in gravity.

D. When the mass increases several times, the gravity also increases several times. Therefore, the mass of an object and its gravity are the same thing.

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

A. The river is not flowing

B. Objects have no mass

C. Once you jump up, you will leave the earth

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

Operation

1. The physical meaning of “g=9.8N/Kg” is ( )

A. 9.8N equals 1Kg

B. 9.8Kg is equal to 1N

C. The gravity experienced by an object with a mass of 9.8Kg is 1N.

D. The gravity experienced by an object with a mass of 1Kg is 9.8N.

2. Among the following objects, the one with a gravity close to 10N is ( )

A. A pencil B. A liter of water

C. A desk D. A microwave oven

3. In October 2005, our country launched the "Shenzhou 6" spacecraft. The spacecraft was in a "weightless" state when flying normally in orbit. In this environment, astronauts Fei Junlong and Nie Haisheng could not perform any of the following experiments like Proceed normally as on the ground ( )

A. Use a scale to measure the length B. Use a magnifying glass to look at the object

C. Use a plane mirror to change the optical path. D. Use a spring dynamometer to measure the weight of an object.

4. After a python with a mass of 50Kg swallows a piglet, its weight reaches 600N. What is the mass of the piglet that was swallowed (g is taken as 10N/kg)?

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

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Update Time: 2024-09-19

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

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