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Newton’s Third Law Of Motion. Statement: To every action, there is an equal and opposite reaction. It means that if body A exerts a force F 1 on body B, and the body B exerts a force F 2 on body A, then: F 1 =F 2. That is, they are equal in magnitude but opposite in direction.
- 108 min
- Overview
- What is Newton's third law?
- What are other examples of Newton's third law?
- Example 1: Fridge push
- Example 2: Third-law-force pairs
Learn about the fact that forces come in pairs.
What is Newton's third law?
You probably know that the Earth pulls down on you. What you might not realize is that you are also pulling up on the Earth. For example, if the Earth is pulling down on you with a gravitational force of 500 N, you are also pulling up on the Earth with a gravitational force of 500 N. This remarkable fact is a consequence of Newton's third law.
Newton's third law: If an object A exerts a force on object B, then object B must exert a force of equal magnitude and opposite direction back on object A.
This law represents a certain symmetry in nature: forces always occur in pairs, and one body cannot exert a force on another without experiencing a force itself. We sometimes refer to this law loosely as action-reaction, where the force exerted is the action and the force experienced as a consequence is the reaction.
We can readily see Newton’s third law at work by taking a look at how people move about. Consider a swimmer pushing off from the side of a pool, as illustrated below.
You probably know that the Earth pulls down on you. What you might not realize is that you are also pulling up on the Earth. For example, if the Earth is pulling down on you with a gravitational force of 500 N, you are also pulling up on the Earth with a gravitational force of 500 N. This remarkable fact is a consequence of Newton's third law.
Newton's third law: If an object A exerts a force on object B, then object B must exert a force of equal magnitude and opposite direction back on object A.
This law represents a certain symmetry in nature: forces always occur in pairs, and one body cannot exert a force on another without experiencing a force itself. We sometimes refer to this law loosely as action-reaction, where the force exerted is the action and the force experienced as a consequence is the reaction.
We can readily see Newton’s third law at work by taking a look at how people move about. Consider a swimmer pushing off from the side of a pool, as illustrated below.
Other examples of Newton’s third law are easy to find. As a professor paces in front of a whiteboard, she exerts a force backward on the floor. The floor exerts a reaction force forward on the professor that causes her to accelerate forward.
Similarly, a car accelerates because the ground pushes forward on the drive wheels in reaction to the drive wheels pushing backward on the ground. You can see evidence of the wheels pushing backward when tires spin on a gravel road and throw rocks backward.
In another example, rockets move forward by expelling gas backward at high velocity. This means the rocket exerts a large backward force on the gas in the rocket combustion chamber, and the gas therefore exerts a large reaction force forward on the rocket. This reaction force is called thrust. It is a common misconception that rockets propel themselves by pushing on the ground or on the air behind them. They actually work better in a vacuum, where they can more readily expel the exhaust gases.
Helicopters similarly create lift by pushing air down, thereby experiencing an upward reaction force. Birds and airplanes also fly by exerting force on air in a direction opposite to that of whatever force they need. For example, the wings of a bird force air downward and backward in order to get lift and forward motion.
A person drives a cart, Cart 1, to the right while pushing another cart, Cart 2, that has a massive refrigerator on it. The total mass of Cart 2, cart plus fridge, is three times the total mass of Cart 1, cart plus person. If the person is driving with enough force that the two carts accelerate to the right, what can be said for sure about the magnitudes of the forces on the carts?
Choose 1 answer:
Choose 1 answer:
•(Choice A)
The force on Cart 2 exerted by Cart 1 is larger in magnitude than the force on Cart 1 exerted by Cart 2.
•(Choice B)
A box sits at rest on a table as seen in the image below. Various forces are listed in the table below the image.
Drag the forces in the right column so that they're lined up with their Newton's third law partner force in the left column.
1
[How do I figure out the solution for this table?]
The strength of the force that the box exerts on you depends on the mass of the box and the amount of force that you apply to it. This is because of something called 'action and reaction'. When you push the object, it is the action, and the object pushing back is the reaction.
- I’m doing this for the “good answer badge” even though I’m just answering a rickroll that’s not even a question xd
- Yes! If the person lets go of the rope, it will go shooting your way.
- yes because fish has four letters
- the hill will be pushing back at you (search up newtons third law)
- The ground pushes on the object being affected by the gravitational force.
- *What do you mean?*
- 730 Million jars of peanut butter to equal the weight of the empire state building.
- Yes! The ball bounces back because scientifically, it “reflects” off of the surface. Some other examples would be looking at yourself in a mirror o...
- since roughly 7.5 gallons of water is in a square foot 16 cups are in a gallon and there is roughly 600,000 square feet of vacant space in the Empi...
The law of action-reaction (Newton's third law) explains the nature of the forces between the two interacting objects. According to the law, the force exerted by object 1 upon object 2 is equal in magnitude and opposite in direction to the force exerted by object 2 upon object 1.
Newton's third law states that for every action there is an equal and opposite reaction. The "action" and "reaction" refer to forces; if Object A exerts a force on Object B, then Object B exerts an equal amount of force on Object A in the opposite direction.
- 8 min
- Sal Khan
Sep 12, 2022 · We sometimes refer to this law loosely as “action-reaction,” where the force exerted is the action and the force experienced as a consequence is the reaction. Newton’s third law has practical uses in analyzing the origin of forces and understanding which forces are external to a system.
Jul 20, 2022 · The Third Law, commonly known as the “action-reaction” law, is the most surprising of the three laws. Newton’s great discovery was that when two objects interact, they each exert the same magnitude of force on each other but in opposite directions.
