in symbols 1 W = 1 J/s
Commonly we use “watt” as a unit of power. Larger powers are given in kilowatts (kW).
1 kW = 1 000 W.
Horsepower (hp) is a unit used for engines. It was first used when steam engines replaced horses as a power source. 1 hp is equal to 746 W.
Table 6.2
Machine
|
Power
|
Moon rocket engine
|
1 00 000 kW
|
Washing machine
|
250 W
|
Car engine
|
100 kW
|
Electric kettle
|
2 kW
|
Iron
|
1.2 W
|
Horse
|
750 W
|
Man
|
500 W
|
Light bulb
|
100 W
|
Typical powers of various machines
Efficiency
We use machines to make work easier. But there is no perfect machine (Figure 4.15). In practice, more energy is put into a machine (work input) than is produced (work output). Because some of the energy input is converted into heat and sound (in small amounts) energy. The efficiency of a machine can be increased if resistive surfaces are lubricated.
The efficiency of a machine is defined as the ratio of the output of work to the input of work, or the ratio of the output of power to the input of power. The following two equations state efficiency in formulas:
Efficiency Work
Energy
output or
input
Efficiency Power
Power
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output input
Тапсырмалар/tasks: Who transfers most energy?
Copy and complete the following.
Rose
Chemical energy energy
Rani
Chemical energy
Copy and complete the following.
as the
……………. energy and
……………. energy
Energy for your body
Your body gets the energy it needs from
Food stores energy. Your body transfers the energy from food mainly as
energy and energy.
When you lift something up, you give it more energy. 4.Copy and complete the table.
Chemical energy
What stores it?
|
Is it a food or a fuel?
|
What you do to transfer the stored energy?
|
potatoes
|
food
|
eat them
|
firewood
|
|
|
child’s body
Look at the photographs. Then copy and complete the following energy transfer diagrams.
Chemical energy …………….
energy
athlete’s body
Chemical energy …………….
energy
Another kind of potential energy
We can store energy in some things by changing their shape. We can do this by stretching them, bending them or squeezing them.
23
Look at the diagrams. Then copy and complete the table.
What changes its shape
|
How do we change its shape?
|
bow
|
|
catapult rubber
|
|
spring
|
|
The stored energy is called elastic potential energy.
Copy and complete the sentence.
A bent bow, stretched rubber and a squashed spring all store potential energy.
Copy and complete the sentences.
A battery stores energy. It transfers energy by when you connect it into a
circuit.
Copy and complete using the key words.
Ways of storing energy
You can store energy as energy, potential energy or potential energy.
Electricity is great for energy, but you can’t electricity. Batteries store energy as energy.
Look at the diagram. Then copy and complete the sentences.
Energy is transferred from a light bulb only partly by .
Energy is transferred from a light bulb mostly as energy.
All the energy goes somewhere Whenever you transfer energy:
only part of the energy is transferred in the way you want;
but all the energy is transferred in some way.
The diagram shows what happens to all the energy transferred to a light bulb.
Copy and complete the following.
Energy transferred TO the light bulb
|
Energy transferred FROM the light bulb
|
electricity
100%
|
light + thermal energy _% +
% total: 100%
|
So:
energy IN = energy OUT
12.30% of the energy that you supply to a yellow sodium street lamp is transferred as light. Draw an energy transfer diagram for this lamp.
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Copy and complete the following.
Energy IN to engine
|
Energy OUT from the engine
|
from fuel
100%
|
kinetic energy + thermal energy + sound
% + % + % total: 100%
|
So:
energy IN = energy OUT
Whenever we transfer energy, some is always transferred in ways we don’t really want. This energy isn’t lost, but it is wasted as far as we are concerned.
Copy and complete using the key words
What you need to remember You don’t only get what you want
When energy is transferred, it is transferred in some way. But some is transferred in ways we don’t really want, so it is .
In the end, all transferred energy is wasted because it gets very .
Thank you Sun
Lots of energy reaches us from the Sun every day. The diagrams show how we can transfer this energy.
Copy and complete the following.
solar
Energy from sunlight ……………….
dddddddddd
Energy from ……….. thermal energy
The Sun is very important to us. Most of our other energy sources wouldn’t be there without the Sun.
Wood
. Copy and complete the sentence. Wood stores energy.
All plants store energy as they grow, We say that they store energy in their biomass
Copy and complete using the key words Thank you, Sun!
Most of our energy sources depend on energy from the . Energy sources which don’t depend on the Sun are: [name three]
How hard is it pressing?
Walking on snow isn’t easy.
It’s a lot easier if you wear snow shoes.
1. Look at the pictures Why do snow shoes make it easier to walk on snow?
25
Copy and complete the sentences
Snow shoes work by spreading out your over a much bigger .
Copy and complete the sentences
The area of a snow shoe is five times than the area of an ordinary shoe. So the pressure of a snow shoe on the snow is five times .
Copy and complete the sentences
With fatter tyres the weight is spread over a area. So there is a pressure on the sand.
Copy and complete the sentences
The sharp edge of a knife blade is much thinner than the edge. So the same force produces a much bigger on the cheese.
Copy and complete using the key words How hard is it pressing?
If you spread out a force over a big area, it will only produce a small . To get a big pressure, you must make a force act on a small .
Making good use of friction
Friction is often a nuisance. So we usually want to reduce it.
But friction can also be very helpful. Then we want to increase it.
Slowing down
To slow down a car or a bicycle, we use the brakes. The diagram shows how the brakes on a bicycle work.
Write down the following sentences in the right order. The first one is in the correct place.
You squeeze the brake lever to pull the cable.
There is a force of friction between the rubber blocks and the wheel.
The wheel shows down.
The rubber blocks press against the wheel.
Look at the diagram. Then copy and complete the sentences.
To make tyres grip, there must be a lot of between the tyres and the road.
To make the friction forces big, we make tyres from and make road surfaces .
Copy and complete using the key words. Making good use of friction.
Between tyres and the road there must be a lot of . If there isn’t, the tyre might .
You slow down car and bicycles by using the .
These use
A parachute uses
friction to slow the wheels down.
_ to slow the parachutist down.
How to make things move.
We often want to start things moving. The diagrams show some examples.
26
Copy and complete the table.
|
What you do to start it moving
|
golf ball
|
|
drawer
|
|
buggy
|
|
Pushing things, pulling things and hitting things are all ways of starting things moving. They move because you make a force act on them.
Look at the diagrams again. Then copy and complete the sentences.
A force acting on an object make it .
The object moves in the same as the force.
Copy and complete the sentences.
To make something slow down you need a _. The force must be in the direction to the way the thing is moving.
Making things change direction.
A football is moving across the goal mouth. The attacker wants the ball to go into the goal. The diagram shows how we can do this.
Copy and complete the sentences.
To change the direction that the ball is moving, the attacker must make a _ act on it. The attacker wants the ball to turn to the right. So he must head it with a force from the
.
31 . Copy and complete using the key words. How to make things move
To start something moving, to speed it up or to change its direction, you must make a act on it. This force must be in the same as you want the thing to move.
If you want to slow something down, the force must be in the direction to the way it is moving.
Copy and complete the table.
Date
|
How high is the Sun at noon?
|
How many hours between sunrise and sunset?
|
What direction is sunrise?
|
What direction is sunset?
|
March 21st
|
|
|
|
|
June 21st
|
|
|
|
|
September 23rd
|
|
|
|
|
December 22nd
|
|
|
|
|
27
The solar system.
The planets look like stars, but they aren’t stars. They don’t give out their own light. They also go round the Sun just kie the Earth does. We say that they orbit the Sun. We call the Sun and all its planets the solar system.
planet
|
Average distance from Sun
(millions of kilometers)
|
Mercury
|
58
|
Venus
|
108
|
Earth
|
150
|
Copy the table
Then add the names of the other planets in order. Start with the planet nearest to the Sun.
Next add the distance or each planet from the Sun.
Why does Mars look bright in this position?
My
|
Very
|
Easy
|
Method
|
Just
|
Speeds
|
Up
|
Naming
|
Planets
|
e
|
e
|
a
|
a
|
u
|
a
|
r
|
e
|
l
|
r
|
n
|
r
|
r
|
p
|
t
|
a
|
p
|
u
|
c
|
u
|
t
|
s
|
i
|
u
|
n
|
t
|
t
|
u
|
s
|
h
|
|
t
|
r
|
u
|
u
|
o
|
r
|
|
|
|
e
|
n
|
s
|
n
|
|
y
|
|
|
|
r
|
|
|
e
|
|
More about pressure. Remember from page 134 Pressure = force + area
Pressure on your body
You weight is the force of the Earth’s gravity on your body.
If you lie down, your weight is spread over a larger area than when you are standing up. So there is a smaller pressure between your body and what it is resting on.
The diagram shows the same person standing, sitting, lying on a bed and floating in water.
When is the pressure on the person’s body:
i) least? ii) greatest?
Give reasons for your answers.
The person’s weight is 600 newtons. Work out the pressure on his body in each case.
Example
Lying down: pressure = 600/0.4
= 1500 N/m2
28
More about moments.
We sometimes need to work out what happens when two turning forces act on a body. To do this, we need to know exactly how big the moment of each force is.
You can work out the moment of a force like this:
Moment of force = size of force * distance if force from the pivot/
Look at the diagram of the see-saw.
Copy and complete the table.
|
Weight (N)
|
Distance from pivot (m)
|
Moment (N*m)
|
Clockwise or anti-clockwise
|
Bog sister
|
|
|
|
|
Young old
|
|
|
|
|
Why does the see-saw balance?
Calculating moments
This diagram shows a girl weighing herself using 10 kilograms of potatoes.
What is the clockwise moment caused by the weight of the potatoes?
What must the anti - clockwise moment of the girl’s weight be?
?What is the weight of the girl (in newtons)?
What is the mass of the girl (in kilograms)?
To undo a nut, you must overcome the moment of the friction force. How big is this moment for the nut shown in the diagram?
Copy and complete using the key words.
More about moments
Moment of a force = of force * of force from the pivot.
29
Қорытынды
Факультатив курсының жинағында 7-сыныптың физика пәні бойынша кіріктіру тапсырмаларының үлгілері, қазақ және ағылшын тілдерінде физикалық терминдер мен шамалар берілген. Бұл факультатив курс бағдарламасы жалпы орта білім беретін мектептердің физика пәні мұғалімдеріне көмекші құрал болары сөзсіз. Ағылшын тіліндегі қосымша мәліметтер оқушылардың өз бетімен жұмыстануына, ынтымақтасуына, жағдайлар жасайтын, кері байланыс орнататын немесе топтық жұмыстарды ұйымдастыруға идея туындататын тапсырмалар жиыны берілген. Физика пәні бойынша ағылшын тілінде материалдар түрлері оқушының ойлау қабілеттерін дамытуға, қызығушылығын арттыруға, теориялық білімін практикамен ұштастыруға, шығармашылық қабілетін, білімін жетілдіру мақсатын көздейді. Бұл жинақта қосымша тапсырмалар және терминдердің ағылшын тілдегі нұсқасын қатар беру мақсаттары көзделген. Бұл оқушының ойлау қабілетін шыңдауға, сыни ойлауға, оқушының дербес мүмкіндіктерін ескеруге, топпен жұмыстануға, уақытты тиімді пайдалануға, сабақты қызықты өткізуге көмектеседі. Мұндай ағылшын тіліндегі терминдер және ағылшын тіліндегі сабақтар мұғалімнің күнделікті іс-тәжірибесінде қолданылатын әдіс-тәсілдерін түрлендіруге, оқушының пәнге деген қызығушылығы мен белсенділігін арттыруға септігін тигізеді, өзіндік мақсатын айқындайды. Бұл жоспар 7 сыныптан оқушының жеке қабілетін және физика пәніне қабілетті балаларды дамытуға және оларды зерттеуге тиімді, әрі осы пәнге байланысты көптеген кедергілерді айқындалады. Әр сабақта тапсырмалардың түрлендіріп берілу оқушының дамуына үлкен үлес қосады. Бұл факультатив курс бағдарламасында берілген қосымша тапсырмалардың ағылшын тіліндегі нұсқасы әр түрлі деңгейде тиянақты және тақырыптары мен мақсаттары сыныпқа айқындалып берілген. Сондықтан бұл жинақ физика пәнінің мұғалімдеріне пайдалы көмекші құрал ретінде ұсынылды.
30
Пайдаланған әдебиеттер
Physics & Astronomy, Grade 7. Авторы: A.Tussyubzhanov, Y.Duiseyev. Астана кітап Алматы 2016 жыл.
Core Physics, Авторы: Bryan Milner, Combridge University Press 1999 жыл. 3.Ағылшынша-қазақша сөздік, авторы: С.Г.Ахметова, Ж.Б.Тұрсынбаева, Ж.Ы.Ысқақова, Е.Ф.Яровая , Алматы, 2006 жыл
Англо-русский словарь, авторы: В.К.Мюллер, 2007 жыл
Oxford Essential Dictionary.Oxford university press, 2015 жыл
Ғаламтор беттерінен bilimland.kz сайты
Физика 7- сынып оқулығы, Алматы: Атамұра, 2017.-208 бет
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