Word
Pronunciation
Translation
attract, v.
/əˈtrækt/
привлекать, притягивать, syn.
pull
average, adj.
/ˈævərɪdʒ/
средний, syn. medium
blade, n.
/bleɪd/
лезвие, клинок
brake, n.
/breɪk/
тормоз
bump, v.
/bʌmp/
столкнуться, врезаться, syn.
collide
dashboard, n.
/ˈdæʃbɔːd/
приборная доска, приборный
щиток, щиток управления
direction, n.
/dɪˈrekʃən/
направление
drop, v.
/drɒp/
ронять
float, v.
/fləʊt/
держаться на поверхности
воды, плавать
force, n.
/fɔːs/
сила, мощь
friction, n.
/ˈfrɪkʃən/
трение
govern, v.
/ˈɡʌvən/
управлять, править,
6
регулировать, syn. rule
gravity, n.
/ˈɡrævəti/
сила тяжести, тяготение, syn.
gravitation, pull
inertia, n.
/ɪˈnɜːʃə/
инерция
invisible, adj.
/ɪnˈvɪzəbl/
невидимый, незаметный
iron, n/adj.
/aɪən/
железо, железный
law, n.
/lɔː/
закон
lump, n.
/lʌmp/
бугор, выступ
marble, n/adj. /ˈmɑːbl/
мрамор, мраморный
mass, n.
/mæs/
масса
molecule, n.
/ˈmɒlɪkjuːl/
молекула
motion, n.
/ˈməʊʃən/
движение, ход, syn. movement
naked, adj.
/ˈneɪkɪd/
обнаженный, голый, syn. bare
obstacle, n.
/ˈɒbstəkl/
препятствие, преграда, syn.
hindrance, obstruction
orbit, n.
/ˈɔːbɪt/
орбита
paw, n.
/pɔː/
лапа
pole, n.
/pəʊl/
полюс
pull, v.
/pʊl/
притягивать(ся)
push, v.
/pʊʃ/
отталкивать(ся)
resistance, n.
/rɪˈzɪstəns/
сопротивление
rink, n.
/rɪŋk/
каток
roll, v.
/rəʊl/
катить(ся), откатывать(ся),
скатывать(ся)
rub, v.
/rʌb/
тереть, втирать, натирать
rug, n.
/rʌɡ/
коврик, ковер
seatbelt, n.
/siːt belt/
ремень безопасности
shaggy, adj.
/ˈʃæɡ.i/
шероховатый
slide, v.
/slaɪd/
скользить, двигаться плавно
smooth, adj.
/smuːð/
гладкий, ровный, syn. even
speed, n.
/spiːd/
скорость (скалярная)
spin, v.
/spɪn/
крутить(ся), вертеть(ся)
7
surface, n.
/ˈsɜːfɪs/
поверхность
terminal, adj.
/ˈtɜːmɪnəl/
конечный
tide, n.
/taɪd/
морской прилив и отлив
universe, n.
/ˈjuːnɪvɜːs/
вселенная
velocity, n.
/vɪˈlɒsəti/
скорость (векторная)
weight, n.
/weɪt/
вес
windshield, n. /ˈwɪndʃɪːld/
ветровое стекло, переднее
стекло
READING
Read and translate the text using a dictionary if necessary:
Motion is the most fundamental observation in nature. Everyday
motion is predictable and deterministic. Predictability is reflected in six
aspects of motion: continuity, conservation, reversibility, mirror-invariance,
relativity and minimization. Some of these aspects are valid for all motion,
and some are valid only for everyday motion.
The world and the Universe are action-packed. People and animals are
always on the move. The planets are constantly circling the Sun. Are there
any rules to all this activity? Our world and the whole Universe are
governed by the laws of nature. Scientists who try to understand and learn
about these laws are called physicists. Here are some questions that
physicists across history have wondered about: When you drop a ball, why
does it fall on the ground? Why does not it float up? If you spin a top, why
does not it spin forever? Why does it eventually stop? Maybe you have
wondered about these things, too.
To answer those questions, physicists needed to discover the laws of
motion. What is motion? Motion is movement in any direction. You can
move up, down, forwards, backwards, and sideways. You can move in
circles. You can wiggle, wave, twist, turn, roll, flip, sway, bend, pivot,
shake, and spin.
A force is a push or a pull. Here is a simple example: A cat hits a ball
with its paw and makes the ball roll across the floor. The cat uses force to
make the ball move. When you kick a ball or pull open a door, you are also
using force. The more force you use, the faster the object will move.
Speed measures how far an object moves in a certain amount of time.
However, things do not always move at the same speed. Forces can cause
8
moving objects to speed up or slow down. «Average speed» equals
«distance divided by time».
So why do things in motion slow down and a stop after a while? The
answer is «friction». Friction is another kind of force. Friction is two things
rubbing or sliding against each other. Skis on snow. A car on a road. A ball
rolling across a carpet. Friction is a force that slows down moving objects.
If you roll a ball across a shaggy rug, you can see that there are lumps and
bumps in the rug that make the ball slow down. The rubbing, or friction,
between the ball and the rug is what makes the ball stop rolling. But what
would happen if you rolled the ball across a very smooth surface and there
was no wall or obstacle in the way? Would the ball keep rolling forever?
Unfortunately, no. There is no such thing as a «frictionless surfacе». There
is friction between all objects and materials when they are touching.
To the naked eye, an object or surface may look perfectly smooth. If
you looked at it under a microscope, you could see the tiny lumps and
bumps that create friction when any two objects slide against each other.
There is even friction when an object moves through the air. The less
friction there is, the longer objects in motion can keep moving. For
example, if you pushed off and tried to slide across the sidewalk in
sneakers, you would not get very far. There is too much friction between the
rubber soles of your sneakers and the rough concrete sidewalk. However, if
you wore ice skates and used the same amount of force to push off and slide
across an ice rink, you would glide for a long way. There is not much
friction between the thin metal blade of an ice skate and the slick ice of the
rink.
Some forces are invisible and can make objects move without touching
them. You have probably played around with magnets before and know that
magnets have an invisible pull—a force that can attract iron and steel
objects. A magnet has a «north pole» and a «south pole». If you take two
magnets, the north pole of one magnet and the south pole of the other will
pull toward each other. If you try to join the north poles of the two magnets,
however, the magnets will push each other away. The same is true if you try
to put the two south poles together—the magnets will repel each other.
Magnets may seem mysterious because they can pull on other objects
and make them move without touching them. It would be wise to mention
that there is another invisible force that you interact with every second of
every day and you probably take it for granted. That force is gravity.
Gravity is the invisible force that holds us to the surface of the Earth.
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Earth’s gravity pulls objects toward the center of the Earth. So when you
drop a book, it falls to the ground instead of floating away. When you jump
up, gravity pulls you back down.
Every object actually has gravity, whether it is the Earth, the Sun, a
person, or just a marble. The more «mass» an object has, the stronger its
force of gravity. Mass just means how much «stuff» is in an object. Some
materials are packed with more stuff than others. For example, steel has
more stuff in it than Styrofoam. If two balls are the same size, and one is
made of foam and one is made of steel, the steel ball will have greater mass.
The Earth and moon both have gravity that is strong enough to pull
them toward each other. Although the moon’s gravity is not as strong as
Earth’s, it pulls on the water in our oceans and creates the tides. So, if the
Earth and moon are pulled toward each other, why don’t they crash into
each other? The moon is held in orbit by the force of Earth’s gravity. The
speed of the moon’s orbit is what prevents the moon from falling down to
Earth. If the moon went slower, it would fall to Earth. If it went faster, it
would escape the Earth’s gravity and fly off into space.
Isaac Newton was a famous scientist who was interested in all sorts of
things, from gravity and the orbits of planets to the rules about how objects
move. One of his most important discoveries is called Newton’s First Law
of Motion. Using experiment and observation, Newton showed that objects
have a tendency to keep doing what they are doing. Objects that are still,
stay still. Objects that are moving, keep moving. A still object stays still and
a moving object keeps moving in the same straight line, unless a force
pushes or pulls it. Whether they are moving of not moving, objects resist
changing their «state of motion». This is called inertia.
Inertia is the reason seatbelts are important. If you are in a fast-moving
car and the driver slams on the brakes, the car will stop, but you will keep
moving forward. The seatbelt stops you, so you do not hit the dashboard or
windshield.
Mass vs. weight. The mass of an object stays the same no matter where
you are in the Universe. That is because the amount of stuff in the object
does not change. Weight is actually the pull of gravity on an object. You
feel your weight because the ground is pushing against the pull of gravity.
So the weight of an object can change depending on where it is in the
Universe. An object that weighs 60 pounds on Earth would weigh only
about 10 pounds on the moon because the force of gravity on the moon is
only one-sixth as strong as it is on Earth. Although your mass would stay
10
the same, you would feel much lighter on the moon or you would if you did
not have to wear that heavy spacesuit.
Air resistance is a kind of friction. Molecules in the air push up against
falling bodies while gravity down. The force of air resistance pulls them
opposes the force of gravity. The friction created by air resistance is not
strong enough to stop falling objects, but it can stop them from speeding up.
Thanks to air resistance, falling objects reach a top speed, also called
«terminal velocity», that is based on their size and mass.
The concepts of force, motion, gravity, mass, and inertia and more
govern the world and our Universe. They are complex ideas but once you
understand them, you will see everything a little more clearly.
(Adopted from
www.kidsdiscover.com
)
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