When regarding Newton's 3rd law, I have a question. It seems like while I study, there is no reaction, the actions act at the same time. Is this correct? And also, I really don't understand why something would "push" back at you. I understand that it happens because of real life examples, I just need clarification on how something can push back. I know this is really basic, I would just like some help. Thanks!
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I think you are just wondering how any body which is inanimate, i.e. material objects can provide reaction force opposed to the action by us humans.
These forces of action and reaction are generated in the material also and is visible when bodies are in equilibrium with each other i. e. no relative motion is being observed.
The reaction forces are always normal to the plane of contact in case of action in contact.
A body which is pulling another one ;say a box on earth -being pulled by gravitational force towards its center is pushed by the earths surface opposite to the action and equal in magnitude otherwise the box can not be at rest- at rest means net force acting on it is zero.
However if the earth's surface fails to provide equal reaction(in case of marshy land) then the body will move by the difference of these two forces and it will go down in the surface till the hard surface(equal reaction to the weight of the body) is reached. thats why you go down on a sandy surface- beach surface- as the particles of sand are not tied as atoms to each other and they slip.
The mechanism of force of reaction is that when you apply a force say on a block of wood, you are trying to deform the arrangement of its atoms which are in an equilibrium under inter atomic forces - if you disturb their arrangement their inter atomic interaction will push you - they do not like being disturbed- you are actually pushing the atoms closer then the inter atomic forces will push you back- why they do that ; imagine the atoms to be at d distance in equilibrium -if you push to reduce d the net force will push you back to go to equilibrium ; if you try to pull them apart they will again pull you to get to their minimum energy state i.e. equilibrium arrangement . every natural system wants to stay in minimum energy state called ground state.
You have a steel wire hung from a rigid support- you hang a weight W . now this weight w will be trying to change the atomic arrangement of the wire , which were in equilibrium- the tendency of the arrangement to come back to ground state gives a pull on the w -this is reaction- now you increase the weight W+ dw - perhaps you have pulled the atoms apart as when you measure the length -you get an increase in length -now you remove the weight dw - you will find the change in length goes to zero - i.e. you are in elastic limit of the wire . so things like to go to their minimum energy configuration. But if you cross the elastic limit to get an equal and opposite reaction the steel becomes plastic-i.e. its change in length does not return to original length and ultimately the wire breaks at certain Weight W(1) -that is breaking weight.
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