Do action force and reaction force lie on same line?

In summary, the conversation discusses the relationship between action and reaction forces in Newton's third law and how it relates to the conservation of angular momentum. It also mentions how cats are able to rotate themselves in mid-air before landing on their feet. The conclusion is that conservation of angular momentum does not prevent changes in angular orientation due to internal torques.
  • #1
fxdung
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Do action force and reaction force(Newton's third law) lie on same line?If not then the angular momentum will be violated.I don't know why a cat falling can rotate itself before contact land if the conservative law of angular momentum not be violated?
 
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  • #2
I know that the conservative law of angular momentum is deduced from the symmetry of rotation of space.So the torque of internal force must be zero,then the action and reaction forces must be lie in same axis.But how to prove action and reaction forces lie in same axis(it seem to me sometime the action and reaction forces not lie on same axis)?
 
  • #3
fxdung said:
Do action force and reaction force(Newton's third law) lie on same line?If not then the angular momentum will be violated.I don't know why a cat falling can rotate itself before contact land if the conservative law of angular momentum not be violated?
The short answer is the cat is not a rigid body. Newtons Laws are inviolate and there are no external torques on the cat but by clever counterotation the cat can get her feet downward without offending Sir isaac.

https://www.huffpost.com/entry/why-cats-always-land-on-their-feet_n_1828748
 
  • #4
Conservation of angular momentum doesn't mean that angular orientation can't be changed due to internal torques. If you were standing on a frictionless surface, you could whirl your arms overhead to change the direction you face. A cat flexes at the middle and whirls it's front half and back half in order to change orientation to face paws down.
 
  • #5
fxdung said:
I don't know why a cat falling can rotate itself before contact land if the conservative law of angular momentum not be violated?
 

1. What is Newton's third law of motion?

Newton's third law of motion states that for every action, there is an equal and opposite reaction. This means that when an object exerts a force on another object, the second object will exert an equal force in the opposite direction on the first object.

2. How does Newton's third law relate to action and reaction forces lying on the same line?

Newton's third law states that the action and reaction forces are equal and opposite. This means that the two forces will have the same magnitude and opposite direction, causing them to lie on the same line.

3. Can the action and reaction forces be on different objects?

Yes, according to Newton's third law, the action and reaction forces can be on different objects. This is because the forces are always equal and opposite, regardless of which objects they are acting on.

4. Do the action and reaction forces always have the same effect on the objects?

No, the effects of the action and reaction forces can be different depending on the mass and acceleration of the objects. For example, if a small object exerts a force on a larger object, the larger object will experience a smaller acceleration compared to the smaller object.

5. Is it possible for the action and reaction forces to cancel each other out?

No, the action and reaction forces cannot cancel each other out because they are acting on different objects. However, they can result in a state of equilibrium where the two forces are balanced and there is no overall acceleration.

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