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Astro 7N Unit 1 Review Notes
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Astro 7N Unit 1 Review Notes
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Astro 7N Unit 1 Review Notes1st Law Of Newton's Laws Of Motion - correct answer-An object at rest, or in motion in a
straight line at a constant speed, will remain in
that state unless acted upon by a force
example:
If the Sun suddenly disappeared, the Earth would continue in the
direction that it was traveling in its orbit at that time.)
2nd law of newton's laws of motion - correct answer-The acceleration of a body due to a
force will be in the same direction as the force,
with a magnitude directly proportional to its mass.
Force = mass x acceleration
(A smaller mass will move faster, if the same force is applied to it.)
3rd law of newton's law of motion - correct answer-For every action, there is an equal and
opposite reaction.
(The Sun exerts force on planets, and they orbit it — the planets exert equal
force on Sun, but it only moves slightly because of its very large mass relative
to the planets.)
Strength of gravity on the surface of a planet - correct answer-g = m/r^2
m = mass
r = radius
more mass = more gravity - correct answer-If the mass of a planet were twice that of
another, but they had the same radius, the
gravity felt on the surface of the more-massive one would be twice as strong.
•
Larger separation = less gravity - correct answer-If the radius of a planet were twice that of
another, the gravity is 1/(2)^2
= 1/4 as strong.
Mars has 1/10 the mass of the Earth and 1/2 the radius of Earth. What is the surface gravity
of mars compared to earth? - correct answer-4/10
force of gravity - correct answer-f is proportional to m1 x m2 / d2
if objects are moved 2 times closer, gravitational attraction is 4 times as great
, What causes day and night? - correct answer-Rotation of the Earth on its axis.
How does the Sun appear to move in the sky in the course of a day? - correct answer-East
to West, because of Earth's rotation. The stars and planets move in the same
way from our point of view, also, because of Earth's rotation.
What happens to the Earth in one year? - correct answer-It orbits the Sun, once (also
referred to as one complete revolution about the Sun).
Why do we have seasons? - correct answer-The tilt of the Earth's axis of rotation, with
respect to the plane of its orbit around
the Sun (and not because of changing distance from Sun).
The Earth's tilt is about 23 degrees.
How is the Earth's axis tilted when we have summer in the Northern hemisphere? - correct
answer-With the North pole toward the Sun.
What season is it in the Southern hemisphere when it is summer in the
Northern hemisphere? - correct answer-Winter.
When does winter begin? - correct answer-Winter begins on or about Dec. 21
= in the Northern hemisphere, the
nights are longer than days
When does spring begin? - correct answer-Spring begins on or about March 21
= days and nights have equal length
When does summer begin? - correct answer-Summer begins on or about June 21
= days longer than nights in the North
When does fall begin? - correct answer-Fall begins on or about Sept. 21
= days and nights have equal length
Without ______ there would be no seasons - correct answer-Seasons would not happen if
the Earth's axis were not tilted.
The distance between the
Earth and the Sun does not change very much over the course of a year, so the tem-
perature does not change much for that reason.
Without the tilt of Earth's axis there would
be no seasons on Earth.
Mars has a similar tilt to its rotation axis as Earth does.
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