17k views

If Newton's third law is true, why can we sink in sand? [duplicate]

Newton's third law of motion states that every action has an equal and opposite reaction. That is the reason we do not sink into the earth, because when our weight exerts a force on the earth it also ...
7k views

Why does the cart move? [duplicate]

A while ago someone proposed the following thought experiment to me: A horse attached to a cart is resting on a horizontal road. If the horse attempts to move by pulling the cart, according to the ...
2k views

Action Reaction when I pushing a trolley? [duplicate]

I tried to explain how those force work but I can hardly figure it out. I exerted a force on the trolley and there will be a force on trolley on me as well. This is the newton's third law. But why the ...
2k views

Why am I not accelerated by the reaction force applied by Earth on me? [duplicate]

Newton's third law says that "to every action, there is always an equal but opposite reaction". And Newton's second law of motion says that, $F=ma$ $=>$ $a=\frac{F}{m}$. People says that If I stand ...
1k views

Why do objects move when you apply a force that's equal in magnitude to the friction? [duplicate]

If the friction on an object is 200 N and you apply 200 N, it seems, the forces should immediately cancel each other out since the friction and your applied force go in opposite directions, leaving ...
936 views

Newton's third law confusions [duplicate]

According to Newton's third law of motion, if body A exerts a force on body B, then body B exerts a force on body A that is equal in size but opposite in direction, then how do things move?
3k views

How are unbalanced forces even possible, given Newton's 3rd law? [duplicate]

The notion of an unbalanced force seems to contradict Newton's third law, entirely. For instance, apparently, if you push a rock, then an unequal force is being applied in the opposite direction with ...
1k views

Newtons Third Law [duplicate]

In Newtons Third Law, it states that for every action, there is an equal but opposite reaction. So that means tat for every action, there will be a reaction to cancel it out. So if that is the case ...
1k views

Tension and Newton's Third Law [duplicate]

I have heard many people tell me that the tensional force is bi-directional. Consider the following case where a (mass-less) rope is used to transmit tension. The rope is being pulled (by hand) with ...
2k views

Clarification regarding Newton's Third Law of Motion and why movement is possible [duplicate]

Newton's third law states that to every action, there is an equal and opposite reaction. If that's the case, then how do things move at all? Shouldn't all applied forces be canceled by the equal and ...
677 views

Action is equal to reaction. Then how is a horse able to pull a cart? [duplicate]

Please answer the question in detail. I have tried other websites for answers but was not able to understand properly.
720 views

two block problem in friction [duplicate]

This is a seemingly basic mechanics problem but I'm having a dilemma in understanding what happens. You start with two blocks, one on top of the other (the bottom block has a larger mass than the top ...
525 views

If I push my hands against each other, why does the stronger one move the weaker one if the forces should be equal and opposite [duplicate]

If I were pushing my hands against each other, the stronger arm will move the weaker arm, but if all forces have an equal and opposite reaction, why does the weaker one move?
511 views

Why doesn't the normal force make things move? [duplicate]

Why won't two blocks kept in contact on a horizontal frictionless surface move, due to the normal force? No exterior force is applied to them from any direction (except for gravity). Ok here's more ...
618 views

According to Newton's third law, why don't Action and Reaction make equilibrium? [duplicate]

According to Newton's third law, Action and Reaction are equal and in opposite direction. If both forces are equal and in opposite direction then why they don't make equilibrium and void the effect of ...
317 views

Why body starts moving when force is applied? [duplicate]

The recent question by m.buettner regarding self-inductance and its resistance to EMF Faraday's law - does the induced current's magnetic field affect the change in flux?, recalled me the ...
526 views

How is the horse able to pull the cart? [duplicate]

To me, the horse's role is merely to transmit the force it is being pushed forward with by the ground over to the cart. So, let's say, the ground pushes horse with 20 N, the horse pulls cart with 20 N,...
185 views

Force balancing - Newtonian mechanics [duplicate]

If a horse pulls the carriage, the carriage should pull the horse with equal force (Newton's third law), then how does the whole system move? I drew the free body diagram but not yet figured what ...
84 views

How is acceleration in cars possible? [duplicate]

Based on the understanding that Newtons third law states for every action there is an equal and opposite reaction, when a car moves forward under driving force, air resistance and friction act equally ...
209 views

Why does Newton's Third Law not preclude any motion at all? [duplicate]

When walking, if I apply a force of 2N on the earth, the earth applies a force of 2N back on my feet due to Newtons 3rd Law of Motion. These 2 forces are equal in magnitude but opposite in direction, ...
435 views

Newton's third law. how things can move? [duplicate]

I am beginner in physics and i have some questions about Newton's third law The law says : When one body exerts a force on a second body, the second body simultaneously exerts a force equal in ...
420 views

Why don't the two forces balance each other In Newton 3rd law? [duplicate]

Why don't the two forces of action and reaction balance each other ? I imagine that although they are opposite forces, they have different points of application. Is this true?
238 views

Action and reaction forces during collision [duplicate]

How can the action and reaction force be same.? And if so then how the colliding objects could further move as there net force is Zero. Since F1 = - F2, that means that the force act on both sides ...
289 views

Newton's third law, why does this body move? [duplicate]

while i have tried reading explanations for why newtons third law doesn't mean objects can't move such as this one: With Newton's third law, why are things capable of moving? I still do not ...
173 views

Surface friction and Newton's third law [duplicate]

My question is regarding a specific case displaying Newton's third law. In the diagram below, a man is shown exerting a force on the wall, which in turn causes an equal and opposite reaction force ...
214 views

Elastic behaviour of objects [duplicate]

If I strike my car with a wrench with enough force to make a dent in it, then it's obvious that I won't be able to produce any acceleration in the car. But I am applying an external deforming force. ...
149 views

How does Newton's 3rd Law apply to arm wrestling? [duplicate]

I understand that when we refer to Newton's third law, forces do not cancel out because action-reaction pair forces are acting on different objects. I tried to apply this to arm wrestling, but I am a ...
80 views

Why is only one end at rest when a rope is attached to a cube? [duplicate]

I know there is something wrong in the way I think about physics generally, but I don't know what it is. Suppose there is a cube with a hook on one face and a rope attached to that hook (see diagram)....
108 views

Newton's 2nd and 3rd Law clarification [duplicate]

Hi I have a quick question. I know this may be a common question. If N3L states that there's an equal and opposite force, why do things still move? I have read up a lot and this is my understanding. ...
59 views

Clarify Torque and static friction [duplicate]

I came to this problem and solved it but I don't fully understand how this works. The problem is: A 200lb man climbs to the top of a 20ft ladder that is leaning against a smooth wall at an angle ...
115 views

Why doesn't air below a falling object balance its weight? [duplicate]

Consider the following scenario: a body is dropped and it hits the air molecules below it with a force equal to it's weight. By Newton's third law, the air molecules below should exert the same force ...
86 views

Boy , Table and the Newton [duplicate]

Suppose a boy is trying to stand on a table. If the table can hold upto a particular force, the boy would fall on to earth. If he stands on the table and providing greater force than the table can ...
64 views

Why is an object pushed when you push it? [duplicate]

According to Newton's third law, if I push an object the object should push me back with the same and opposite force. So there should be no net force, which means that it shouldn't be displaced (...
81 views

Newton's third law confusion [duplicate]

If A exerts a force of 200N on B, then by newton's third law, 200N would be exerted on it. Similarly, if B exerts 100N on A, by newton's third law, 100N would be exerted on it. Therefore the net ...
61 views

How are objects able to move even after newton's third law of motion [duplicate]

I can't understand at all why objects move even though after newton's third law.I also have a doubt in following example If we apply a force on an object the object applies a backward push on us ...
45 views

How can any object move? [duplicate]

If an object A exerts a force on another object B, an equal and opposite force will be applied on object A by object B, so that means for a force to be applied on object B by object A, a force must ...
68 views

Newtons third law explanation on a push of table [duplicate]

I read this example of pushing a table with your hands. So the force is applied on the table to push and the table exerts the same amount of force on our hands. My question is, if the forces are ...
37 views

If every object could give an equal and opposite force to what we apply then why do the objects exhibit translatory and rotational motion? [duplicate]

If I push a block on a frictionless surface with enough force, it begins to move. Shouldn't it be standing still if it exerts an equal force on me as per 3rd law?
43 views

Doubt on Newton's third law of motion [duplicate]

Okay, so if I have 2 blocks of different masses 4kg and 2kg placed side by side with possibly a distance of 1 molecule between them (sorry if the diagram doesn't show that). There is negligible ...
41 views

How Newton's third law is involved in a tug of war? [duplicate]

Using Newton's third law, we can say that each team applies the same force on the opposite team. Then how one wins? Is it due to ground friction?
35 views

How does Force translate a body if each molecule if pulled with a force,pulls the next molecule and still the body moves? [duplicate]

In diagram 1,F pulls the body. The molecule in contact with F gives an equal normal reaction opposite to F,the same happens with each molecule,how does the body move then? In diagram 2, is the logic ...
17 views

Newton's Third Law? [duplicate]

I've recently met with this new law and the way my teacher worded is so off for me. Shouldn't the equal and opposite reaction cancel out the action because they are equal? Apparently not? Why?
30k views

Is Newton's third law always correct?

Newton's third law states that every force has an equal and opposite reaction. But this doesn't seem like the case in the following scenario: For example, a person punches a wall and the wall breaks. ...
11k views

How does the force of tension really work?

I am currently studying high school physics (I'm in the first year of high school). The force of tension initially seemed to be a simple concept, but unfortunately has proved rather challenging to ...
63k views

If something that is moving at constant velocity has no net force acting on it, how come it is able to move other objects?

Let's say 10 kg block is sliding on a frictionless surface at a constant velocity, thus its acceleration is 0. According to Newton's second law of motion, the force acting on the block is 0: $a = 0$...
5k views

How can a car's engine move the car?

Newton's First Law of Motion states that an object at rest or uniform motion tends to stay in that state of motion unless an unbalanced, external force acts on it. Say if I were in a car and I push ...
2k views

Newton's Third Law of Motion

I want to start off by saying that I've looked around for other explanations, but I've not really found any satisfying ones. My question is basically the whole "Why can anything move at all?" question,...
8k views

What force enables us to walk?

When we walk, we apply a force $F$ on the earth at an angle $\theta$ . Thus, by Newton's third law, $$F_{\text{me, earth}}=-F_{\text{earth,me}}$$ Therefore, the earth exerts a reaction force on us, ...