ASTRO 7N EXAM 1
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📋 DOCUMENT OVERVIEW 98 Qs
This document, "Astro 7N Exam 1," covers astronomy topics such as the force of gravity, Newton's laws
of motion, surface gravity, blackbody spectrum, electromagnetic radiation, and the formation of the
Solar System. It provides 98 questions with correct answers and detailed explanations, including
diagrams and images, making it a valuable resource for studying and reviewing these concepts.
Students can use this document to deepen their understanding of astronomy concepts, review key
ideas, and prepare for exams.
✓ Verified Answers ✓ Exam Ready ✓ Study Guide
Trusted by thousands of students and professionals worldwide
EXAM QUESTIONS
QUESTION 1
The force of gravity by the Sun keeps the planet in orbit around it, but how do the planets affect the
sun?
CORRECT ANSWER
They exert an equally strong pull on the sun, causing it move slightly
RATIONALE: The planets exert a gravitational force on the sun, but this force is much weaker than the sun's
gravitational force on the planets due to the significant mass difference between the sun and the planets. However, in
accordance with Newton's third law of motion, the gravitational force exerted by the planets on the sun is equal in
magnitude to the force exerted by the sun on the planets, resulting in a slight pull on the sun.
QUESTION 2
Newton's First Law
CORRECT ANSWER
An object at rest stays at rest and an object in motion stays in motion with the same speed and in the
same direction unless acted upon by an unbalanced force.
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, ex: if the sun suddenly disappeared, the Earth would continue in the direction that it was traveling in its
orbit at that time
RATIONALE: This is correct because Newton's First Law, also known as the Law of Inertia, describes the relationship
between an object's motion and the forces acting upon it, explaining that an object will maintain its state unless an
external force alters it. The example of the Earth continuing in its orbit after the sun disappears illustrates this concept
by showing that the Earth's motion is self-sustaining and only changes when an external force, in this case the sun's
gravitational pull, is removed or altered.
QUESTION 3
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 magnitude
directly proportional to its mass
Force = mass x acceleration
A smaller mas will move faster, if the same force is applied to it
RATIONALE: Newton's Second Law is correct because it accurately describes the relationship between force, mass, and
acceleration, which is a fundamental principle of physics where a change in motion is proportional to the force applied.
The law captures the concept that for a given force, a smaller mass will experience a greater acceleration due to the
reduced resistance to change its motion.
QUESTION 4
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 - he planets exert equal force on Sun, but it only moves
slightly because of its very large mass relative to the planets
RATIONALE: Newton's Third Law is based on the idea that forces always come in pairs, where the force exerted by one
object on another is equal in magnitude to the force exerted by that second object on the first. The key concept here is
that the force exerted by the Sun on a planet is not a solo action, but rather part of a reciprocal relationship where the
planet's force on the Sun is equal in magnitude, although the effect on the Sun is minimal due to its greater mass.
QUESTION 5
Surface Gravity on a Planet
CORRECT ANSWER
the strength of gravity: g = m/r^2
where M is the mass of the planet and R is its radius. Note the radius is squared but the mass is not.
More mass = 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.
Larger separation = less gravity.
- If the radius of a planet were twice that of another, the gravity is 1 / (2) 2 = 1/4 as strong.
Putting the effects of mass and radius together, you should be able to figure out the surface gravity of
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, Mars, relative to the Earth.
- Mars has 1/10 the mass of the Earth and 1/2 the radius of Earth. So for Mars,
g = (1/10) / (1/2) 2 = (1/10) / (1/4) = 4/10
Mars has a surface gravity 4/10 that of Earth. You will need to be able to do this type of estimate for the
test, given the numbers for mass and radius.
RATIONALE: The strength of gravity on a planet is determined by the inverse square relationship between the mass of
the planet and the radius of the planet, resulting in a formula where the mass is directly proportional to the gravity, but
the radius is inversely proportional to the square of the gravity. This means that doubling the mass of a planet doubles
its gravity, but doubling its radius decreases its gravity by a quarter, which allows for estimates of surface gravity based
on mass and radius ratios.
QUESTION 6
If I apply exactly the same amount of force to a pebble and a boulder, what will happen
CORRECT ANSWER
the pebble will move faster
RATIONALE: The pebble will move faster because it has less mass, so the same amount of force applied to it results in
a greater acceleration according to Newton's second law of motion, which states that force is equal to mass times
acceleration (F = ma). This means that with less mass, the pebble requires less force to achieve the same acceleration
as the boulder, causing it to move faster when the same amount of force is applied.
QUESTION 7
If the Earth were moved to half its current distance from the sun, how would the force of gravity by
the sun on the earth change?
CORRECT ANSWER
it would become 4 times weaker
RATIONALE: The force of gravity between two objects is determined by the inverse square law, which states that the
force is inversely proportional to the square of the distance between them. When the Earth is moved to half its current
distance from the sun, the gravitational force would increase, but because the force is inversely proportional to the
square of the distance, it would only be 4 times stronger, not weaker.
QUESTION 8
Mass
CORRECT ANSWER
As the mass of the planet increases, the jump height does decreases by the same factor
As the mass of the planet decreases, the jump height does increases by the same factor
RATIONALE: The relationship between mass and jump height is determined by the acceleration due to gravity, which is
inversely proportional to the square root of the planet's mass. This means that as the mass of the planet increases, the
acceleration due to gravity decreases, resulting in a decrease in jump height, and vice versa.
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, QUESTION 9
According to Newton's Second law of motion, if the net force acting on the object increases while the
mass of the object remains constant, what happens to acceleration
CORRECT ANSWER
acceleration increases
RATIONALE: Newton's Second law of motion, F = ma, shows a direct relationship between force and acceleration,
where acceleration is the result of dividing the net force by the object's mass. If the net force acting on the object
increases while the mass remains constant, the acceleration will increase because the denominator (mass) remains the
same, but the numerator (force) increases, resulting in a greater overall ratio.
QUESTION 10
If the earth were moves to half its current distance from the Sun, how would the force of gravity by
the Sun on the Earth change
CORRECT ANSWER
it would become four times weaker
RATIONALE: The force of gravity between two objects is determined by their masses and the square of the distance
between them, as described by Newton's law of universal gravitation. Since the distance between the Earth and the Sun
would be halved, the force of gravity would decrease by a factor of 2 squared, or four, resulting in the force becoming
four times weaker.
QUESTION 11
What did newton's law of universal gravitation tell us about how gravity works
CORRECT ANSWER
the force of gravity from the sun will be stronger on object with more mass
RATIONALE: Newton's Law of Universal Gravitation states that every point mass attracts every other point mass by a
force acting along the line intersecting both points. This force is proportional to the product of the two masses and
inversely proportional to the square of the distance between them, meaning objects with more mass will experience a
stronger gravitational pull from other masses.
QUESTION 12
If you were to sit on the ground, there would be a force due to gravity pulling you toward the earth.
which of the following is true according to newton's third law
CORRECT ANSWER
you are pushing the earth away from yourself with the same force
Trusted by thousands of students and professionals worldwide Page 4 of 41
95+ (Latest 2026) Complete Exam Prep Kit | Verified Q&A with Detailed
Rationales
100% Guarantee Pass
📋 DOCUMENT OVERVIEW 98 Qs
This document, "Astro 7N Exam 1," covers astronomy topics such as the force of gravity, Newton's laws
of motion, surface gravity, blackbody spectrum, electromagnetic radiation, and the formation of the
Solar System. It provides 98 questions with correct answers and detailed explanations, including
diagrams and images, making it a valuable resource for studying and reviewing these concepts.
Students can use this document to deepen their understanding of astronomy concepts, review key
ideas, and prepare for exams.
✓ Verified Answers ✓ Exam Ready ✓ Study Guide
Trusted by thousands of students and professionals worldwide
EXAM QUESTIONS
QUESTION 1
The force of gravity by the Sun keeps the planet in orbit around it, but how do the planets affect the
sun?
CORRECT ANSWER
They exert an equally strong pull on the sun, causing it move slightly
RATIONALE: The planets exert a gravitational force on the sun, but this force is much weaker than the sun's
gravitational force on the planets due to the significant mass difference between the sun and the planets. However, in
accordance with Newton's third law of motion, the gravitational force exerted by the planets on the sun is equal in
magnitude to the force exerted by the sun on the planets, resulting in a slight pull on the sun.
QUESTION 2
Newton's First Law
CORRECT ANSWER
An object at rest stays at rest and an object in motion stays in motion with the same speed and in the
same direction unless acted upon by an unbalanced force.
Trusted by thousands of students and professionals worldwide Page 1 of 41
, ex: if the sun suddenly disappeared, the Earth would continue in the direction that it was traveling in its
orbit at that time
RATIONALE: This is correct because Newton's First Law, also known as the Law of Inertia, describes the relationship
between an object's motion and the forces acting upon it, explaining that an object will maintain its state unless an
external force alters it. The example of the Earth continuing in its orbit after the sun disappears illustrates this concept
by showing that the Earth's motion is self-sustaining and only changes when an external force, in this case the sun's
gravitational pull, is removed or altered.
QUESTION 3
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 magnitude
directly proportional to its mass
Force = mass x acceleration
A smaller mas will move faster, if the same force is applied to it
RATIONALE: Newton's Second Law is correct because it accurately describes the relationship between force, mass, and
acceleration, which is a fundamental principle of physics where a change in motion is proportional to the force applied.
The law captures the concept that for a given force, a smaller mass will experience a greater acceleration due to the
reduced resistance to change its motion.
QUESTION 4
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 - he planets exert equal force on Sun, but it only moves
slightly because of its very large mass relative to the planets
RATIONALE: Newton's Third Law is based on the idea that forces always come in pairs, where the force exerted by one
object on another is equal in magnitude to the force exerted by that second object on the first. The key concept here is
that the force exerted by the Sun on a planet is not a solo action, but rather part of a reciprocal relationship where the
planet's force on the Sun is equal in magnitude, although the effect on the Sun is minimal due to its greater mass.
QUESTION 5
Surface Gravity on a Planet
CORRECT ANSWER
the strength of gravity: g = m/r^2
where M is the mass of the planet and R is its radius. Note the radius is squared but the mass is not.
More mass = 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.
Larger separation = less gravity.
- If the radius of a planet were twice that of another, the gravity is 1 / (2) 2 = 1/4 as strong.
Putting the effects of mass and radius together, you should be able to figure out the surface gravity of
Trusted by thousands of students and professionals worldwide Page 2 of 41
, Mars, relative to the Earth.
- Mars has 1/10 the mass of the Earth and 1/2 the radius of Earth. So for Mars,
g = (1/10) / (1/2) 2 = (1/10) / (1/4) = 4/10
Mars has a surface gravity 4/10 that of Earth. You will need to be able to do this type of estimate for the
test, given the numbers for mass and radius.
RATIONALE: The strength of gravity on a planet is determined by the inverse square relationship between the mass of
the planet and the radius of the planet, resulting in a formula where the mass is directly proportional to the gravity, but
the radius is inversely proportional to the square of the gravity. This means that doubling the mass of a planet doubles
its gravity, but doubling its radius decreases its gravity by a quarter, which allows for estimates of surface gravity based
on mass and radius ratios.
QUESTION 6
If I apply exactly the same amount of force to a pebble and a boulder, what will happen
CORRECT ANSWER
the pebble will move faster
RATIONALE: The pebble will move faster because it has less mass, so the same amount of force applied to it results in
a greater acceleration according to Newton's second law of motion, which states that force is equal to mass times
acceleration (F = ma). This means that with less mass, the pebble requires less force to achieve the same acceleration
as the boulder, causing it to move faster when the same amount of force is applied.
QUESTION 7
If the Earth were moved to half its current distance from the sun, how would the force of gravity by
the sun on the earth change?
CORRECT ANSWER
it would become 4 times weaker
RATIONALE: The force of gravity between two objects is determined by the inverse square law, which states that the
force is inversely proportional to the square of the distance between them. When the Earth is moved to half its current
distance from the sun, the gravitational force would increase, but because the force is inversely proportional to the
square of the distance, it would only be 4 times stronger, not weaker.
QUESTION 8
Mass
CORRECT ANSWER
As the mass of the planet increases, the jump height does decreases by the same factor
As the mass of the planet decreases, the jump height does increases by the same factor
RATIONALE: The relationship between mass and jump height is determined by the acceleration due to gravity, which is
inversely proportional to the square root of the planet's mass. This means that as the mass of the planet increases, the
acceleration due to gravity decreases, resulting in a decrease in jump height, and vice versa.
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, QUESTION 9
According to Newton's Second law of motion, if the net force acting on the object increases while the
mass of the object remains constant, what happens to acceleration
CORRECT ANSWER
acceleration increases
RATIONALE: Newton's Second law of motion, F = ma, shows a direct relationship between force and acceleration,
where acceleration is the result of dividing the net force by the object's mass. If the net force acting on the object
increases while the mass remains constant, the acceleration will increase because the denominator (mass) remains the
same, but the numerator (force) increases, resulting in a greater overall ratio.
QUESTION 10
If the earth were moves to half its current distance from the Sun, how would the force of gravity by
the Sun on the Earth change
CORRECT ANSWER
it would become four times weaker
RATIONALE: The force of gravity between two objects is determined by their masses and the square of the distance
between them, as described by Newton's law of universal gravitation. Since the distance between the Earth and the Sun
would be halved, the force of gravity would decrease by a factor of 2 squared, or four, resulting in the force becoming
four times weaker.
QUESTION 11
What did newton's law of universal gravitation tell us about how gravity works
CORRECT ANSWER
the force of gravity from the sun will be stronger on object with more mass
RATIONALE: Newton's Law of Universal Gravitation states that every point mass attracts every other point mass by a
force acting along the line intersecting both points. This force is proportional to the product of the two masses and
inversely proportional to the square of the distance between them, meaning objects with more mass will experience a
stronger gravitational pull from other masses.
QUESTION 12
If you were to sit on the ground, there would be a force due to gravity pulling you toward the earth.
which of the following is true according to newton's third law
CORRECT ANSWER
you are pushing the earth away from yourself with the same force
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