1 / 7

Newton’s 3 rd Law

Newton’s 3 rd Law. Newton’s 2 nd Law : A quantitative description of how forces affect motion BUT : Where do forces come from? EXPERIMENTS show that Forces applied to an object are ALWAYS applied by another object  Newton’s 3 rd Law

akristie
Download Presentation

Newton’s 3 rd Law

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Newton’s 3rd Law Newton’s 2nd Law: A quantitative description of how forces affect motion • BUT:Where do forces come from? EXPERIMENTSshow that Forces applied to an object are ALWAYS applied byanotherobject  Newton’s 3rd Law “Whenever one object exerts a forceF on a second object, the second object exerts an equal & opposite force -F on the first object.” • The “Law of Action-Reaction” “Every action has an equal & opposite reaction”. (Note that action-reaction forces act onDIFFERENTobjects!)

  2. “If two objects interact, the force F12 exerted by object 1 on object 2 is equal in magnitude & opposite in direction to the force F21 exerted by object 2 on object 1.” As in the figure Another Statement of Newton’s 3rd Law

  3. Example: Newton’s 3rd Law When a force is exerted on an object, that force is caused by another object. Newton’s 3rd Law: “Whenever one object exerts a force on a second object, the second exerts an equal force in the opposite direction on the first.” If your hand pushes against the edge of a desk (the force vector shown in red), the desk pushes back against your hand (this force vector is shown in purple, to remind us that this force acts on a DIFFERENT object).

  4. Newton’s 3rd Law: Alternative Statements 1.Forcesalwaysoccur in pairs 2.A single isolated forcecannotexist 3.The “action force” is equal in magnitude to the “reaction force” & opposite in direction a. One of the forces is the “action force”, the other is the “reaction force” b. It doesn’t matter which is considered the “action” & which the “reaction” c. The action & reaction forces must act on different objects & be of the same type

  5. Action-Reaction Pairs: Act on Different Objects The key to correct the application ofNewton’s 3rd Lawis: The forces are exerted on different objects.Make sure you don’t use them as if they were acting on the same object. Example: When an ice skater pushes against the railing, the railing pushes back & this reaction force causes her to move away.

  6. Rocket propulsion can be explained using Newton’s Third Law:Hot gases from combustion spew out of the tail of the rocket at high speeds. The reaction force is what propels the rocket. Note:The rocket doesn’t need anything to “push” against.

More Related