Newton's Third Law
A force is a push or a pull upon an object that results from its interaction with another object. Forces result from interactions! According to Newton, whenever objects A and B interact with each other, they exert forces upon each other. When you sit in your chair, your body exerts a downward force on the chair and the chair exerts an upward force on your body. There are two forces resulting from this interaction a force on the chair and a force on your body. These two forces are called action and reaction forces and are the subject of Newton's third law of motion. Formally stated, Newton's third law is:
For every action, there is an equal and opposite reaction.
A variety of action-reaction force pairs are evident in nature. Consider the propulsion of a fish through the water. A fish uses its fins to push water backwards. But a push on the water will only serve to accelerate the water. Since forces result from mutual interactions, the water must also be pushing the fish forwards, propelling the fish through the water. The size of the force on the water equals the size of the force on the fish; the direction of the force on the water (backwards) is opposite the direction of the force on the fish (forwards). For every action, there is an equal (in size) and opposite (in direction) reaction force. Action-reaction force pairs make it possible for fish to swim.
Consider the motion of a car on the way to school. A car is equipped with wheels that spin in a clockwise direction. As the wheels spin clockwise, they grip the road and push the road backwards. Since forces result from mutual interactions, the road must also be pushing the wheels forward. The size of the force on the road equals the size of the force on the wheels (or car); the direction of the force on the road (backwards) is opposite the direction of the force on the wheels (forwards). For every action, there is an equal (in size) and opposite (in direction) reaction. Action-reaction force pairs make it possible for cars to move along a roadway surface.
The Physics Classroom
http://www.physicsclassroom.com/class/newtlaws/u2l4a.cfm
How does something such as a distribution of force occur for example a football player getting tackled? How is it that force is not distributed only to points of contact between two forces?
ReplyDeleteKyle Green
I have heard this quote (For every action, there is an equal and opposite reaction) many times before and now I fully understand what it means. It is easier to see Newton's third law in action when you push against a table for example, however it is hard for me to wrap my head around this law in action when you drop something onto the ground. The Earth actually exerts the same force to that object and moves towards the object. Since the Earth is so massive you cant see this with your own eyes but it happens.
ReplyDeleteThe examples in this article were really helpful to visualize how the 3rd law of motion works.
ReplyDeleteThanks for this!!! It really helped me understand the VERY IMPORTANT 3rd law of motion.
ReplyDeleteI think Newton's Third Law is my favorite of his laws :)
ReplyDeleteShandale McKay:
ReplyDeleteThe examples in this article really helped me to understand Newton's Third Law better.
These examples definitely helped one visualize Newtons 3rd law!
ReplyDeleteI love the visualization for the third law, very creative.
ReplyDeleteLori Waite
Kelsey Irvine:
ReplyDeleteI love both the bird cartoon and the bird example
I have always heard of Newtons 3rd Law but I never fully understood it until this class. At first I thought there was no way for Newtons 3rd Law to be true 100% of the time. This article also aided in my understanding. Thanks!
ReplyDeleteThe bird cartoon was awesome and it really helped me remember Newtons 3rd law with the visuals.
ReplyDeleteGreat post, the cartoon is very helpful.
ReplyDeleteJessica Lang
the examples really help understand Newtons 3rd law.
ReplyDelete- Tulsi Patel