Newton's Third Law: Equal Forces & Stationary Object?

In summary, Newton's Third Law states that for every action, there is an equal and opposite reaction. This means that when body A exerts a force on body B, body B will exert an equal force on body A. However, this law does not apply to the sum of forces on a single body, which is described by Newton's First Law. In this case, if there are no other forces acting on body A and B, the net force on the system will be zero, resulting in either no movement or constant velocity of the center of mass.
  • #1
Lim Y K
26
0
The Newton's third law states that the force exerted by body A on body B is equal to the force exerted by Body B on Body A . In this case, isn't the object supposed to be stationary because equal forces are acting on both sides?
Can someone please explain to me . Thanks
 
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  • #2
Which object?
 
  • #3
Lim Y K said:
The Newton's third law states that the force exerted by body A on body B is equal to the force exerted by Body B on Body A . In this case, isn't the object supposed to be stationary because equal forces are acting on both sides?
Can someone please explain to me . Thanks

The force exerted on body A causes body A to move.
The force exerted on body B causes body B to move.
These are two different forces acting on two different bodies; Newton's third law says that they will be of equal magnitude and opposite direction.

Search this forum and google for "cart-horse paradox" for more detail.
 
  • #4
Lim Y K said:
In this case, isn't the object supposed to be stationary because equal forces are acting on both sides?

If there are no other forces acting on A and B, then the net force on the system of A and B together is indeed zero. It has an important physical consequence: the center of mass of the system either remains at rest, or moves at constant velocity according to Newton's First Law.
 
  • #5
Lim Y K said:
The Newton's third law states that the force exerted by body A on body B is equal to the force exerted by Body B on Body A . In this case, isn't the object supposed to be stationary because equal forces are acting on both sides?
Can someone please explain to me . Thanks
Newton's Third Law applies to the interaction between one body and another and not the sum of Forces on a single Body, which says that you need a net unbalanced force for acceleration to take place. That's Newton 1. Each of the forces acting on a body (say the strings pulling it and the table it rests on) will have equal and opposite reaction forces - the mass pushes down on the table with the same force as the table keeping the mass up (N3). The tension in the string is the same in both directions (N3) - whether or not the string is causing the mass to accelerate (N1).
 

What is Newton's Third Law?

Newton's Third Law, also known as the Law of Action and Reaction, states that for every action, there is an equal and opposite reaction.

Can you give an example of Newton's Third Law in everyday life?

Yes, one example is when you push against a wall, the wall pushes back on you with an equal force in the opposite direction.

How does Newton's Third Law relate to equal forces and a stationary object?

Newton's Third Law states that when two objects interact, they exert equal and opposite forces on each other. In the case of a stationary object, the object exerts an equal and opposite force on the object pushing against it, resulting in no movement.

Does Newton's Third Law apply to all forces?

Yes, Newton's Third Law applies to all forces, whether they are contact forces (pushing, pulling) or non-contact forces (gravity, magnetism).

How does Newton's Third Law impact our understanding of motion?

Newton's Third Law helps us understand that motion is the result of forces acting on objects. It also explains why objects tend to stay at rest or in motion unless acted upon by an external force.

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