Question

question #1
what is the relationship between the force you apply to a heavy box and the force the box applies back to you?
a. the forces are equal in strength but act in the same direction.
b. the force you apply is stronger than the force the box applies back.
c. the forces are equal in strength but act in opposite directions.
d. the force the box applies back is stronger than the force you apply.
question #2
according to the text, what is a good example of force pairs in action?
a. a bird flying in the air.
b. a car driving down a road.
c. a person sitting on a chair.
d. a book lying on a table.
question #3
what is the main idea of newton’s third law of motion as explained in the text?
a. every action has an equal and opposite reaction.
b. objects at rest stay at rest, and objects in motion stay in motion.
c. force equals mass times acceleration.
d. the force of gravity pulls all objects towards the center of the earth.

Explanation:

Question #1

To solve this, we recall Newton's Third Law of Motion, which states that for every action, there is an equal and opposite reaction. When you apply a force to a box, the box applies a force back on you. These forces (action - reaction pair) should be equal in magnitude (strength) and opposite in direction.

• Option A is incorrect because the forces act in opposite, not the same, direction.
• Option B is incorrect as the forces are equal in strength (Newton's Third Law).
• Option D is incorrect as the forces are equal in strength.

We need to identify a situation that shows a force pair (action - reaction) in action. Let's analyze each option:

• Option A: A bird flying - The bird pushes air down (action), and the air pushes the bird up (reaction). But let's check other options too.
• Option B: A car driving down a road - The car's tires push the road backward (action), and the road pushes the tires forward (reaction). But let's see the best fit.
• Option C: A person sitting on a chair - The person exerts a downward force on the chair (action), and the chair exerts an upward normal force on the person (reaction). This is a direct example of a force pair (action - reaction) as the two forces (person on chair and chair on person) are equal and opposite.
• Option D: A book lying on a table - The book exerts a downward force on the table, and the table exerts an upward force on the book. But compared to option C, a person sitting is a more direct action - reaction in terms of "in action" (the action of sitting involves the force pair). Wait, actually, all have force pairs, but let's re - evaluate. Wait, the key is "force pairs in action". When a person sits, the action (person's weight on chair) and reaction (chair's normal force on person) are a force pair. But let's check the options again. Wait, maybe a better way: A bird flying: the bird's wings push air (action), air pushes wings (reaction). But the question is about "force pairs in action" (maybe a more static or direct). Wait, actually, the correct answer is C? Wait, no, let's think again. Wait, a person sitting on a chair: the person applies a force on the chair (action), and the chair applies a force on the person (reaction). But let's check the options. Wait, maybe the best answer is C? Wait, no, let's re - check. Wait, the options:

Wait, let's recall Newton's Third Law. The force pair consists of two forces, one on each object. For a person sitting on a chair: Object 1 (person) exerts force on Object 2 (chair), and Object 2 (chair) exerts force on Object 1 (person). So this is a force pair. Let's check other options:

• Option D: A book lying on a table - similar to the chair example, but the question is about "in action" (maybe a more dynamic? No, the question says "good example of force pairs in action" which can be static too. Wait, but let's see the options again. Wait, maybe I made a mistake. Wait, the correct answer is C? Wait, no, let's think again. Wait, a bird flying: the bird's wings push air down (action), air pushes bird up (reaction) - that's a force pair. A car driving: tires push road back, road pushes tires forward - force pair. A person sitting: person pushes chair down, chair pushes person up - force pair. A book on table: book pushes table down, table pushes book up - force pair. But which is the "good example"? Wait, maybe the question is looking for the most direct. Wait, the answer is C? Wait, no, let's check the options again. Wait, the correct answer is C? Wait, maybe. Let's confirm: when a person sits on a chair, the action is the person's weight (force on chair), reaction is the normal force (chair on person). So this is a force pair. So option C is correct.

We need to find the main idea of Newton's Third Law of Motion. Let's recall the laws of motion:

• Newton's First Law: Objects at rest stay at rest, and objects in motion stay in motion (Option B) - so B is First Law.
• Newton's Second Law: Force equals mass times acceleration ($F = ma$) (Option C) - so C is Second Law.
• Newton's Third Law: Every action has an equal and opposite reaction (Option A).
• Option D is about gravity, not Newton's Third Law.

Answer:

C. The forces are equal in strength but act in opposite directions.

Question #2