The 9 planets
orbit the Sun because of the gravitational attraction between them.
Quick Check -
Which of these is
true about the Sun
The Sun ____
is a star and is not in the center of the solar system is not a star and is in the center of the solar system is a star and is in the center of the solar system
Which of these
revolves around a planet?
an asteroid a moon a star
2. What is Air Pressure?
pressure is the force put
on you by the weight of air molecules.
You know that air molecules are invisible,
but they still have weight and take up
The air molecules are
pushing against your body right now. Do you think the force (how
hard they are pressing) is
greater pressing down on
the top of your head greater pressing on the sides of
your body equal in all directions
3. What is the Atmosphere?
The atmosphere is
the air that surrounds the Earth. We live at the bottom of a
'sea of air'. The higher you go in the atmosphere, the less air
molecules there are in the 'sea of air'.
If there are less
air molecules, does that mean the air pressure increases or decreases as
you go higher?
increases (more) decreases (less)
4. Why don't I feel the
The reason you don't
get squished by the pressure of the atmosphere is because you have air
inside your body. The air inside your body is the same as the
pressure on the outside.
When you drive up
the mountains to Los Angeles, what happens to your ears?
Your ears pop
because the air pressure is different as you go higher through the
mountains. When the air inside your body changes so that it will
be the same as the new pressure outside your body, your ears pop.
Is the pressure in
the mountains higher or lower than here in the valley?
5. Try It!
balloon filled with air can't release the air inside as it goes higher,
like we can. What do you think would happen to a balloon as it
rises higher and higher in the air?
Remember - the air outside the balloon will have less pressure as it get