Astro 7n Exam 1 (Unit 1 & 2) Questions with Complete
Solutions 100% Verified
Newton's First Law 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
Ex) If the Sun suddenly disappeared, the Earth would ...
Astro 7n Exam 1 (Unit 1 & 2) Questions with Complete
Solutions 100% Verified
Newton's First Law 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
Ex) If the Sun suddenly disappeared, the Earth would continue in the direction that it was
traveling in its orbit at that time
Newton's Second Law 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 * Acceleration
-(A smaller mass will move faster, if the same force is applied to it.)
Newton's Third Law 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
The strength of gravity, g, on the surface of a planet is given by: Correct answer-g=M/R^2
where M is the mass of the planet and R is its radius
What does more mass mean? Correct answer--More gravity
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
, Astro 7n Exam 1 (Unit 1 & 2) Questions with Complete
Solutions 100% Verified
What does larger separation mean? Correct answer--Less gravity
If the radius of a planet were twice that of another, the gravity is 1/(2)^2 = 1/4 as strong
Figure out the surface gravity of Mars, relative to the Earth
Mars has 1/10 the mass of the Earth and 1/2 the radius of Earth. So for Mars, Correct
answer-g= (1/10)/(1/2)^2 = (1/10)/(1/4) = 4/10
-Mars has a surface gravity 4/10 that of Earth
Newton's Universal Law of Gravitation Correct answer-This law gives the force of gravity
between any two objects in the Universe. The force of gravity is proportional to (Mass of object
1) * (Mass of object 2) divided by the distance between the two objects squared:
F ∝ M1 x M2 / d^2
If the objects were moved 2 times closer (or, to half of their initial distance between) ...
Correct answer-F ∝ M1 x M2 / (1/2)^2 = M1 x M2 / (1/4) = 4 (M1 x M2) so the
gravitational attraction would because 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
, Astro 7n Exam 1 (Unit 1 & 2) Questions with Complete
Solutions 100% Verified
What happens to the Earth in one year? Correct answer-It orbits the Sun, once
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 (The 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 and what does that mean? Correct answer-On or about
December 21 = in the Northern hemisphere, the nights are longer than days
When does Spring begin and what does that mean? Correct answer-On or about March
21 = days and nights have equal length
When does Summer begin and what does that mean? Correct answer-On or about June
21 = days longer than nights in the North
When does Fall begin and what does that mean? Correct answer-On or about September
21 = days and nights have equal length
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