Third law Definition and 371 Threads

For some reason I couldn't answer this, and I hope you can help me: a) Two people pull on a rope, one with 200 N , the other 100 N. Why is the tension on the rope the shared magnitude of both forces? b) If two people pull on a rope with equal force (say, 100 N), each person pulling feels...

I have seen a discussion of what would happen for an ideal gas expands irreversibly and adiabatically until absolute zero degree K. The entropy change is like that: Δs=Cv ln(T2/T1)+R ln(V2/V1) It is impossible for T2 to be zero K in the equation and so it becomes one justification of the...

Homework Statement The planet Jupiter has at least 14 satellites. One of them, Callisto, has a period of 16.75 days and a mean orbital radius of 1.883 x 109 m. From this information, calculate the mass of Jupiter. Homework Equations T2 = (4∏2/ GM)r3 ∏ = pi The Attempt at a...

dear sir, we know that third law of motion says that every action has a equal and opposite reaction. quantum mechanics tells us that it is possible not predict the position as well as the speed of electron. i like to know if electrons ,protons and neutrons form a system called atom...

For two two bodies of mass M1 and M2 in circular orbits of radius a1, a2 about their common centre of mass, the Newtonian modification of Kepler's third law is a3/P2=G(M1+M2)/4π2. Where a=a1+a2. The problem is that I have been told that when using the units of years, solar masses and...

Please look at picture. Here are my equations: For 10kg: -uk m2 g cosθ -T -m2 g sinθ=m2 a For 20kg: T-m1 g =m1 a Add them: -uk m2 g cosθ -m2 g sinθ -m1 g =(m2+m1) a a= 5 m/s^2 (kinematics equations) Isolating uk gives 3.66! The real answer is 0.16. Where am I going wrong?

I have always been under the impression that Newton's third law and the law of conservation of linear momentum are really the same thing; synonymous, so to speak. But then I was wondering if Newton's Third Law holds for a non-isolated system. I mean, I know for sure that momentum conservation is...

Newton's third law confusion? If A exerts some force on B then it experiences a force of same magnitude and in opposite direction. This didn't seem intuitive to me so I thought of it this way, Let A and B be a single system. Now there is no net external force acting on the system so the...

Newton's Third Law states that for every action force, there is a reaction force. So take a classical problem with a basketball player. The Earth has a gravitational force on the player, and thus player exerts an equal and opposite force on the earth. The player is stationary. My first...

Homework Statement Find the period of a satellite that is in orbit 6.7×10^6 meters from the center of the earth? Homework Equations P^2=R^3 P=period and R=average distance The Attempt at a Solution so far I have tried P^2=(6.7×10^6)^3 then sqrt of (P^2)=sqrt of (3.00763×10^20)...

Homework Statement A chain of three links, each with a mass 0.2 kg, is being pulled up by a person lifting the top link with 8.88 N of force and the chain accelerates upward. Calculate three forces that are acting on the middle link while the chain is accelerating. Homework Equations ƩF = ma...

Homework Statement Two hockey players are standing stationary on the ice facing one another. Player A has a mass of 85kg and Player B is 110kg. They shove each other and player A ends up with a velocity of 1.5m/s [W]. Find the final velocity of Player B. Solution Fa=Maaa Fa=(85)(1.5-0/t)...

"For every action there is an equal and opposite reaction." I'm having a difficult time wrapping my head around this. I'm having a hard time applying it to certain situations. For example, a hammer hitting a nail, but more presently a problem in my homework. A building is being torn down...

Homework Statement A diver with a weight of 833 N dives from a boat with a mass of 375kg. If he leaves the boat with a velocity of 2.25m/s [W] after accelerating for 0.50s, what will be the final velocity of the boat? The attempt at a solution ad=Vfd-Vid/t =2.25-0/0.5 ad=4.5m/s^2 [W]...

Homework Statement A paintball with a mass of 0.15 kg is fired from a paintball gun that has a mass of 5.5kg. The paintball leaves the gun with a velocity of 45 m/s [N] having accelerated for 0.10s. Calculate the acceleration and the final velocity of the paintball gun.

I have a question for which I am intensely confused. Lets say a car was pushing a big truck from behind. And the car (and truck) are accelerating, then there is a breakdown because the car applies all the force it has to the truck, which pushes back with equal force. So the car shouldn't be...

Hello, I have seen several explanations on the Internet about how to resolve Newton's Third Law and Unbalanced Forces, but none made sense to me in a way that I really understood it. Scenario 1: There is a block on the ground, the ground has friction with say static friction force 10 N...

Homework Statement A 2000kg car pushes a 1000kg garbage can at constant speed . The car exerts a force of magnitude CB on the garbage can, and the garbage can exerts a force BC on the car. Which force has greater magnitude, or are they equal? explain Homework Equations Fcb=-Fbc The...

If Newtons third law says there is an equal and opposite reaction how can there be energy transfer. For example if I push a box and give it 1000 joules of energy wouldn't it "give back" the energy. Also does an object have to be moved for it to gain energy, if I were to punch a book many times...

According to Coulomb's third law of friction, the sliding friction if independent of the sliding speed. But if the sliding speed is very slow, wouldn't the sliding friction be more? The object's surface will get more time to interact with the surface of the floor and static friction can...

Sorry guys not a physicist!Only wish to know if there is agreement between Newton laws of motion and SR/GR in particular?I know these two don't match in some cases? What are they in simple words please!? Cheers

Hello! When studying the law I noticed that the change in magnetic field (i.e the magnet's motion) is = to the EMF induced. That proofs to me how the principle of the conservation of energy is applied to the world of electromagnetism as well! The energy applied to move the magnet is...

Hi does the Third law of motion have any thing to do with the magnetic force like in a electric motor ?

There seems to be a problem with radiation reaction force. Let's look at charged sphere, attached on a rod to an object with larger mass, and rotating around its centre together with it. The rotating charged sphere emits radiation with power P. The sphere's speed is V. Assuming energy is...

Homework Statement two hockey players are standing on ice. Player A is 100kg and player B is 112kg, Player A pushes B with 40N and player B pushes A with 50N. what are the action/reaction forces? what are the accelerations?Homework Equations F = maThe Attempt at a Solution player A has a...

I have a quick question on Newton's third law. When a 100kg astronaut in space is holding a 100 kg rock and then pushes it away from him with 50 joules of energy (the kinetic energy put into the system) and a second astronaut (observer) is watching, sitting still relatively to the location...

1. A 0.0048kg pullet traveling with a speed of 200m/s penetrates a large wooden fence post. If the average resisting force exerted on the bullet was 4500N how far did the bullet penetrate. 2. F=ma? 3. F = ma F/m = a 4500/0.0048 = 937500? So there's a reverse acceleration of...

question is 29./ about bob and throwing his rock, I have found a./ (225N) easily enough it is b./ which i cannot figure out. I am assuming that it is a Newtonian action-reaction pair and that the rock pushes back on bob at 225N as well, which would mean Bob's acceleration would be 3.0ms/s^2. But...

Assuming $$\vec{r_{a}}$$ and $$\vec{r_{b}}$$ is calculated from an inertial frame of reference. then for any two objects (named a and b) in a system of more than two objects, Is this the Newton's third law, $$\frac{d^{2}}{dt^{2}}m_{a}\vec{r_{a}}=-\frac{d^{2}}{dt^{2}}m_{b}\vec{r_{b}}$$...

Hello 1- work done to push body forward is greater than to pull body backward what is the explanation for this?can you draw the two FBD in both cases ? 2- why is nail driven in wooden wall but not in the concrete wall ؟ I guess this is somehow related to Newton's third law Thanks

For every force exerted by object A on object B, an equal and opposing force is exerted by object B on object A. I need help understanding the principle. I understand it when dealing with a completely stationary object: pushing on a solid wall, it exerts an equal force back to your hand...

Homework Statement Suppose you have a cantaloupe (C) on a table (T). Let FTC be the force on the table by the cantaloupe, and let FCT be the force on the cantaloupe by the table. Do the magnitudes of these forces increase, decrease, or stay the same if they are placed in an elevator which...

Homework Statement Two Blocks, A (10kg) and B (12kg) are placed next to each other on a rough surface. An applied force acting on block A causes both blocks to accelerate at 1.2m/s^2 to the right. If the magnitude of the force of friction on Block B is 18.3N, calculate the force (magnitude and...

hey people,greetings to everyone i'm an freshman in physics so i have some problems understanding Newton's third law. for example how can a motor accelerate an elevator upward,or downward?i know Newton's third law acts on different objects,i understood the house and the cart problem. horse is...

Two wrestlers are pushing each other. Initially the wrestlers are at rest, however the small wrestler starts to move. Now in either cases, which wrestler exerts more force? My professor said that both exert the same amount of force on each other. This is really confusing as if they are applying...

This is going to be a stupid question, for which I apologize. I am probably over-thinking things but my reasoning is flawed somewhere because when I think about Newton's Third Law and it's application to real-world examples, I can't understand how objects move at all, whether accelerating or...

Homework Statement Pluto is 40 times further from the Sun than we are. How long is a year on Pluto? (Use Kepler's third law.) Homework Equations 4∏^2/Gm=T^2/r^3 The Attempt at a Solution Te^2(Earth period)=x*r^3 Tp^2(Pluto period)=x*(40r)^3 I don't know what to do...

1) Does anyone have a general idea of how to experimentally validate or falsify the Third Law of Thermodynamics in its strong form? In another thread, I suggested a procedure for validating the third law of thermodynamics in its weak form. Basically, one determines the specific heat...

Sometimes I wonder if it actually possible to prove the action-reaction principle. I do know that Newtons laws are empirical but then if you think about the third law it says that in interaction between two bodies they exert equal and opposite forces on each other. Now what happens in the...

Homework Statement A satellite is to be placed in orbit about the Earth at an altitude of 1.6 x 10 6m. What will be its period of motion? The answer is 7.2x 103s 2. The attempt at a solution Using kelper's third law. R3 / T2 = R3 / T2 Radius of satellite: 6.38 x 106 + 1.6 x 106...

When we push a body say for example,a crate on ground.Then in response to our force the crate also exerts a force on our hands.Then my question is why does the crate move forward and not we that move backward?

Hi all, I have a general question about board breaking. This is not homework. Can anyone explain why it hurts more not breaking the board, compared to breaking the board. I know that there are already threads about this topic. However, I am confused about the different explanations: 1...

Please anybody explain me ... if i punch a soft cushion hardly say "F" force will thw cusion hurt me with the same ... every body says "NO" ok all right everybody says "you, in this case have not applied the "F" force because most part of it is wasted in changing the shape of cusion " so here...

I push on a wall and the wall pushes me back (according to Newton's third law), but what i don't understand is that no acceleration is produced hence is it not that i have not applied any force? If i jump then i return to the ground (obviously) then doesn't the Earth accelerate towards me...

Newton's Third Law states that every action has an equal and opposite reaction. I'm wondering if and how this applies to magnetism. I would assume that it would mean if a moving charge is creating a magnetic field that causes a magnetic force on another charge, then it can be said that the...

Homework Statement When I push my belly forward, a force is exerted on my belly by my muscles. So there will be a reaction force acting on the muscles right? But eventually it has a net forward force. So if we treat the belly as one object (muscle fat everything in the belly) then where is the...

Hw can we relate conervation of momentum with Newton's third law?? Hw can we relate conervation of momentum with Newton's third law??.. Quantitavely and qualitatevely i want a clarification for the realation between these.. Assume an apple falling towards earth.. Thanks in advance

Action and reaction do not balance each other.But then why a book lying on a table lies at rest?The reaction force and the gravitational force cannot balance each other.Then how is it?

Newton third law! Hi fellow members! I would like to ask a silly question because my basic concepts are quit weak. Since according to Newton third law, with every action, an opposite and Equal force react to resist motion.Since both ACTion and Reaction forces are equal, they will cancel each...

So, I was studying coupled oscillations and came across a statement that I couldn't figure out. It was that a particular matrix was symmetrical by Newton's Third Law. I know what Newton's Third Law is, I know what symmetric matrix is. But, for example, a matrix like this: -2k/m...