Law of universal gravitatLaw of universal gravitationion

（万有引力定律）（万有引力定律）

.

------ established by

Isaac Newton (1642–1727), British ， great physicist, mathematician, astronomer（天文学家）

• Inertia（惯性定律）

• F=MA

• Equal and opposite

Newton’s three important laws?

Finish the match-work according to common sense or your life experience

1.Inertia （惯性定律）2. F=MA

3. Equal and opposite

a. T0 push a child in a swing

b. To calculate what’s required to launch a jet fighter from an aircraft carrier.

c. When the car you’re in begins to move, your body is pushed back against the seat.

d. To walk on the ground.

e. When you whirl a ball on a string and then let it go, it flies straight.

f. To ride a planet around the sun.

The First LawScan the passage and find out :What is inertia?

------Objects at rest tend to remain at rest, while moving ones continue to move at a uniform speed in a straight line------ unless acted upon by an outside force. This resistance to change is called inertia.

not moving

without change

s

Can you try translating the definition of “inertia” into Chinese?

a kind of force to prevent another force

affected

Supported by the first example---

When the car or airplane you’re in begins to move, your body is __________ against the seat. That is, it tends to remain _________ despite the forward-moving force of the vehicle transferred to you through the seat.

Move from one

place to another

pushed back

at rest

Supported by the second example---

When you whirl something around your head---such as a ball on a string--- and then let it go, the ball flies _______ instead of flying in a ________________.

straight sweeping curve

Group discussion Can you tell some cases about

“inertia” in your daily life? Pat one's clothes to get the dust off Stumbled by a stone ( given by your Physics teacher)

Try to recite the first law------ “inertia” within 1 minute

Key words:

at rest,

uniform,

act upon,

resistance

The Second Law Scan the passage and find out----What does

“F=MA” state?

-------Whenever you want to change the speed or direction of something, you have to apply an appropriate force. The bigger the mass or the larger the intended acceleration, the greater the necessary force.

Can you try translating it?

Skim “ F=MA”, and find out how many examples are mentioned about this law.

Supported by four examples------

To push a child in a swing

To ride a planet around the sun

To calculate what’s required to launch a jet fighter from an aircraft carrier

To restrain a person with a seatbelt

喷气式战斗机

航空母舰

hold back

Try to recite the statement of the second law----- “F=MA” within 30 seconds

Key words: apply ,

the more…the more…

The Third Law

Scan the passage and find out: What does “equal and opposite” hold and explain?

-------In nature, unaccompanied forces do not exist. For every action there is an equal and opposite reaction.

without ___________company

Can you try translating it?

being on the other side

Please observe an experiment and then exchange the conclusion that you draw with your friends

---Each time the ______ pushes down on the _____ ,

the ______ pushes back with the same amount of _____ pointed in the precisely the ___________ direction.

What’s the function of the glass-tube?---To _____the friction between the glass-tube and the

board. A. reduce B. increase

car boardboard force

opposite

A

Food for thought---It is not difficult to remember the laws. It is not difficult to demonstrate the laws. However, it is far from easy to discover and establish the laws and it is far from easy to achieve great success.

The reason why smart persons cannot succeed is that they lack the tenacious will.

---- Newton （ England ） strong

Never forget

Assignment:1. Read the new words and expressions in

Vocabulary ( )Ⅱ2. Finish the exercises on Page 83 in the Ⅱ

textbook.

3. Collect 2 more examples for each law and confirm the accuracy with your Physics teacher.