Identify Action-Reaction Force Pairs - Physics
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Identify the reaction force to: a book pushes down on a table.
Identify the reaction force to: a book pushes down on a table.
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The table pushes up on the book. The table responds with an equal upward normal force on the book.
The table pushes up on the book. The table responds with an equal upward normal force on the book.
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What must be true about the magnitudes of forces in an action-reaction pair?
What must be true about the magnitudes of forces in an action-reaction pair?
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They are equal in magnitude. Newton's third law requires forces in pairs to have identical magnitudes.
They are equal in magnitude. Newton's third law requires forces in pairs to have identical magnitudes.
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Identify the reaction force to: a hand pushes on a wall.
Identify the reaction force to: a hand pushes on a wall.
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The wall pushes on the hand. By Newton's third law, the wall exerts an equal force back on the hand.
The wall pushes on the hand. By Newton's third law, the wall exerts an equal force back on the hand.
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Identify the reaction force to: a rocket pushes exhaust gases backward.
Identify the reaction force to: a rocket pushes exhaust gases backward.
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The exhaust gases push the rocket forward. Rocket propulsion relies on action-reaction between rocket and gases.
The exhaust gases push the rocket forward. Rocket propulsion relies on action-reaction between rocket and gases.
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Identify the reaction force to: a person pulls upward on a rope in a tug system.
Identify the reaction force to: a person pulls upward on a rope in a tug system.
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The rope pulls downward on the person. Tension forces in rope create equal and opposite pulls on both ends.
The rope pulls downward on the person. Tension forces in rope create equal and opposite pulls on both ends.
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Identify the reaction force to: a swimmer pushes water backward with their hands.
Identify the reaction force to: a swimmer pushes water backward with their hands.
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The water pushes the swimmer forward. By Newton's third law, water exerts equal force forward on swimmer.
The water pushes the swimmer forward. By Newton's third law, water exerts equal force forward on swimmer.
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Which option is the action-reaction pair for tension: rope pulls on a crate to the right?
Which option is the action-reaction pair for tension: rope pulls on a crate to the right?
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Crate pulls on the rope to the left. Tension creates equal and opposite forces at each end of the rope.
Crate pulls on the rope to the left. Tension creates equal and opposite forces at each end of the rope.
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Find the action-reaction pair: air pushes upward on a parachute (drag force).
Find the action-reaction pair: air pushes upward on a parachute (drag force).
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The parachute pushes downward on the air. Air resistance pairs: air pushes parachute up, parachute pushes air down.
The parachute pushes downward on the air. Air resistance pairs: air pushes parachute up, parachute pushes air down.
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Identify the reaction force to: a hammer exerts a force on a nail.
Identify the reaction force to: a hammer exerts a force on a nail.
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The nail exerts a force on the hammer. Impact forces are mutual - the nail pushes back on the hammer.
The nail exerts a force on the hammer. Impact forces are mutual - the nail pushes back on the hammer.
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Identify whether these two forces are a third-law pair: weight on a book and normal on the book.
Identify whether these two forces are a third-law pair: weight on a book and normal on the book.
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No; both forces act on the book, so they are not a third-law pair. Third law requires different objects; weight and normal both act on book.
No; both forces act on the book, so they are not a third-law pair. Third law requires different objects; weight and normal both act on book.
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Identify the reaction force to: a bat exerts a force on a baseball during impact.
Identify the reaction force to: a bat exerts a force on a baseball during impact.
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The baseball exerts a force on the bat. Contact forces during collision are always mutual between objects.
The baseball exerts a force on the bat. Contact forces during collision are always mutual between objects.
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Identify the reaction force to: the road exerts friction backward on a skidding tire.
Identify the reaction force to: the road exerts friction backward on a skidding tire.
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The tire exerts friction forward on the road. During skidding, friction forces form an action-reaction pair.
The tire exerts friction forward on the road. During skidding, friction forces form an action-reaction pair.
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Identify the reaction force to: a tire pushes backward on the road during acceleration.
Identify the reaction force to: a tire pushes backward on the road during acceleration.
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The road pushes forward on the tire. Friction pairs: tire pushes road backward, road pushes tire forward.
The road pushes forward on the tire. Friction pairs: tire pushes road backward, road pushes tire forward.
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Which statement is correct: action-reaction forces cancel on one object, or act on different objects?
Which statement is correct: action-reaction forces cancel on one object, or act on different objects?
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They act on different objects, so they do not cancel on one object. Third law pairs can't cancel because they act on separate objects.
They act on different objects, so they do not cancel on one object. Third law pairs can't cancel because they act on separate objects.
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What is Newton's third law statement used to identify action-reaction force pairs?
What is Newton's third law statement used to identify action-reaction force pairs?
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Forces occur in equal-magnitude, opposite-direction pairs on different objects. Newton's third law states every action has an equal and opposite reaction.
Forces occur in equal-magnitude, opposite-direction pairs on different objects. Newton's third law states every action has an equal and opposite reaction.
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Identify the reaction force to: the ground pushes up on a standing person (normal force).
Identify the reaction force to: the ground pushes up on a standing person (normal force).
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The person pushes down on the ground. The normal force from ground has its reaction as person pushing down.
The person pushes down on the ground. The normal force from ground has its reaction as person pushing down.
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Identify the reaction force to: a magnet pulls a paperclip toward the magnet.
Identify the reaction force to: a magnet pulls a paperclip toward the magnet.
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The paperclip pulls the magnet toward the paperclip. Magnetic forces are mutual - both objects pull on each other equally.
The paperclip pulls the magnet toward the paperclip. Magnetic forces are mutual - both objects pull on each other equally.
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Which requirement must be true for two forces to be an action-reaction pair: same object or different objects?
Which requirement must be true for two forces to be an action-reaction pair: same object or different objects?
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Different objects. Third law pairs always act on two separate objects, never the same one.
Different objects. Third law pairs always act on two separate objects, never the same one.
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What must be true about the directions of forces in an action-reaction pair?
What must be true about the directions of forces in an action-reaction pair?
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They are opposite in direction. Action-reaction pairs point in opposite directions along the same line.
They are opposite in direction. Action-reaction pairs point in opposite directions along the same line.
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Identify the reaction force to: Earth pulls a falling apple downward (gravity).
Identify the reaction force to: Earth pulls a falling apple downward (gravity).
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The apple pulls Earth upward (gravity). By Newton's third law, gravitational forces are mutual between objects.
The apple pulls Earth upward (gravity). By Newton's third law, gravitational forces are mutual between objects.
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Identify the reaction force to: A person pushes the ground backward while walking.
Identify the reaction force to: A person pushes the ground backward while walking.
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The ground pushes the person forward. Walking involves pushing ground backward; ground pushes person forward.
The ground pushes the person forward. Walking involves pushing ground backward; ground pushes person forward.
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Identify the reaction force to: The ground exerts friction on a shoe forward.
Identify the reaction force to: The ground exerts friction on a shoe forward.
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The shoe exerts friction on the ground backward. Friction forces form action-reaction pairs between surfaces.
The shoe exerts friction on the ground backward. Friction forces form action-reaction pairs between surfaces.
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Identify the reaction force to: A car tire pushes the road backward.
Identify the reaction force to: A car tire pushes the road backward.
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The road pushes the tire forward. Cars move forward because tires push road backward, road pushes tire forward.
The road pushes the tire forward. Cars move forward because tires push road backward, road pushes tire forward.
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Identify the reaction force to: Air exerts drag backward on a moving cyclist.
Identify the reaction force to: Air exerts drag backward on a moving cyclist.
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The cyclist exerts a forward force on the air. Air resistance has a reaction: the object pushes air in opposite direction.
The cyclist exerts a forward force on the air. Air resistance has a reaction: the object pushes air in opposite direction.
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If object $A$ exerts force $\vec{F}_{A\to B}$ on $B$, what is the reaction force notation?
If object $A$ exerts force $\vec{F}_{A\to B}$ on $B$, what is the reaction force notation?
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$\vec{F}_{B\to A}$. Subscripts reverse for reaction force: $A$ on $B$ becomes $B$ on $A$.
$\vec{F}_{B\to A}$. Subscripts reverse for reaction force: $A$ on $B$ becomes $B$ on $A$.
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Which pair is an action-reaction pair: weight and normal on a book, or book-on-table and table-on-book?
Which pair is an action-reaction pair: weight and normal on a book, or book-on-table and table-on-book?
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Book-on-table and table-on-book. Weight involves Earth; normal involves table. Book-table forces are paired.
Book-on-table and table-on-book. Weight involves Earth; normal involves table. Book-table forces are paired.
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Which statement is correct about action-reaction forces: do they cancel in a free-body diagram?
Which statement is correct about action-reaction forces: do they cancel in a free-body diagram?
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No; they act on different objects, so they are not on one free-body diagram. Action-reaction pairs act on different objects, never appear together in FBD.
No; they act on different objects, so they are not on one free-body diagram. Action-reaction pairs act on different objects, never appear together in FBD.
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Identify the reaction force to: A charged rod exerts an electric force on a charged ball.
Identify the reaction force to: A charged rod exerts an electric force on a charged ball.
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The charged ball exerts an electric force on the rod. Electric forces obey Newton's third law; both charges exert equal forces.
The charged ball exerts an electric force on the rod. Electric forces obey Newton's third law; both charges exert equal forces.
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Identify the reaction force to: A magnet pulls a paperclip toward it.
Identify the reaction force to: A magnet pulls a paperclip toward it.
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The paperclip pulls the magnet toward it. Magnetic forces are mutual; both objects attract each other equally.
The paperclip pulls the magnet toward it. Magnetic forces are mutual; both objects attract each other equally.
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Identify the reaction force to: A rocket pushes exhaust gases downward.
Identify the reaction force to: A rocket pushes exhaust gases downward.
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The exhaust gases push the rocket upward. Rocket propulsion: gases push rocket up as rocket pushes gases down.
The exhaust gases push the rocket upward. Rocket propulsion: gases push rocket up as rocket pushes gases down.
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