The third law of thermodynamics states as follows, regarding the properties of closed systems in thermodynamic equilibrium: The entropy of a system approaches a constant value as its temperature approaches absolute zero. This constant value cannot depend on any other parameters characterizing the closed system, such as pressure or applied magnetic field. At absolute zero (zero kelvins) the system must be in a state with the minimum possible energy. Entropy is related to the number of accessible microstates, and there is typically one unique state (called the ground state) with minimum energy. In such a case, the entropy at absolute zero will be exactly zero. If the system does not have a well-defined order (if its order is glassy, for example), then there may remain some finite entropy as the system is brought to very low temperatures, either because the system becomes locked into a configuration with non-minimal energy or because the minimum energy state is non-unique. The constant value is called the residual entropy of the system. The entropy is essentially a state-function meaning the inherent value of different atoms, molecules, and other configurations of particles including subatomic or atomic material is defined by entropy, which can be discovered near 0 K.
The Nernst–Simon statement of the third law of thermodynamics concerns thermodynamic processes at a fixed, low temperature: The entropy change associated with any condensed system undergoing a reversible isothermal process approaches zero as the temperature at which it is performed approaches 0 K. Here a condensed system refers to liquids and solids.
A classical formulation by Nernst (actually a consequence of the Third Law) is: It is impossible for any process, no matter how idealized, to reduce the entropy of a system to its absolute-zero value in a finite number of operations.
There also exists a formulation of the third law which approaches the subject by postulating a specific energy behavior: If the composite of two thermodynamic systems constitutes an isolated system, then any energy exchange in any form between those two systems is bounded.
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...
Homework Statement
An object is free to move on a table, ex-
cept that there is a constant friction force f
that opposes the motion of the object when
it moves. If a force of 10 N pulls the object
across the table, the acceleration is 2 m/s2. If
a force of 20 N pulls the object across the...
Homework Statement
An elevator containing 3 passengers(with a mass of 72kg 84 kg and 35 kg) has a mass combined of 1030 kg . The cable attached to the elevator exherts an upward force of 12000 N. But the friction opposing the motion of the elevator is 1400 N.
a) Draw a free body diagram...
Is Newton's third law valid in non-inertial frames? For example, in a rotating frame of reference, can Newton's third law still be applied? Or does the non-inertial character of the frame violate it?
why do paddles/oars have a large surface area? I thought that it does not really matter as i would just apply a force on the water so as to attain a action-reaction force on the boat thus pushing me forward. but if i look at the free body diagram of the paddle 1 force will be me pushing and the...
Whats more basic - Newtons third law or conservation of momentum
You can prove Newtons third law by conservation of momentum but you can also prove conservation of momentum by Newtons third law. What comes first?
When I exert a force, I will experience an equal and opposite force on two mutual bodies. However, when I break through a wall how do the free body diagrams of my hand and the wall? When the wall doesn't break, the forces on the hand is normal contact force on my hand from the wall and a force...
Homework Statement
Consider Atwood's machine with two masses, m1 and m2 with m1 less than m2. Now, according to application of Newton's third law, the system accelerates in the direction of the heavier mass (here, m2). This, however, seems to contradict Newton's third law, which implies that...
I'm kinda confused with Newton's Third Law.
Let me present my problem.
Say I kicked the floor with 50N, the floor pushes me back with 50N, there is a reaction pair.
But say if I kicked the air with 50N, why aren't I feeling the 50N? By right it should feel the same right?
Alright, so I have this sheet for homework and I'm not sure where to start.
Incase you are unable to see, the questions say:
a) What is the acceleration of the system and the tension in each rope if the girl lifts with a force of 100.0N?
b) What is the force that she pulls with if T3...
I'm just a humble human being here, so if my question comes across as stupid, please forgive me! :)
Newton's Third Law of Motion states that for every action there is an equal (in magnitude) but opposite (in direction) reaction. One of my A-level revision guidebooks state that the attraction...
Hello,
I have a question from a conceptual problem in my textbook as follows:
A car is moving north and speeding up to pass a truck on a level road. The combined contact force exerted on the road by all four tires has vertical component 11.0 kN downward and horizontal component 3.3 kN...
I was recently reading about artificial gravity and generating it in space, especially by centripetal force using Stanford Tori and Bernal sphere (only Wikipedia and these to articles, but if anyone has any more resources, I would be glad to read them, I couldn't find anything else in my...
Homework Statement
Kepler's third law of planetary motion relates P, the period of a planet's orbit, to R, the planet's mean distance from the sun, through the equation log P = \frac{1}{2} (log K + 3log R), where K is a constant.
Rewrite the formula as a single logarithm.
Homework...
Lets say that I have a cart on a track with silly putty on the end. This first cart is moving with an initial "x" velocity. There is another cart about a foot ahead of it with sillyputty on its bumper also. (Both carts have the same mass) This cart has an initial velocity of zero. Of course...
Hi friendz
I m new to this forum
I have a problem in a question which is as follows-
If a body of mass m collides with a body of mass 2m it changes its direction of motion buy when it collides with a body of same mass m it stops and when it collides with a body of mass m/2 it does not change...
Coloumbs law states that the force exerted by two charged particles on each other is given by f = kq1q2/d^2
Now say two charged particles (charge type irrelevant in question) x and y are d metres from each other then y exerts a force f on x. But since x is also exerting f on y then won't it...
Hi,
I am confused on a certain part of Newton's third law. I know that it states that for every action force there is an equal and opposite reaction force that act of different objects. So, let's say you have an elevator that is suspended by a cable. The elevator's mass is 1kg (I know this...
Homework Statement
Two packages at UPS star sliding down a 20° ramp. Package A has mass of 5.0 kg and coefficient of friction of 0.20. Package B has a mass of 10 kg and a coefficient of friction of 0.15. How long does it take package A to reach the bottom?
Homework Equations
N/A
The Attempt...
Hi,
I was in an elevator the other day and I began to think about the forces acting on me and the elevator during my ascent and I became very confused.
Let's say for example that my mass and the elevator's mass combined is 100kg so this weighs 98N. When the elevator is at rest I figured...
1. Tug Of War: Person A is bigger and stronger than Person B, and chooses to neither pull on the rope, or allows Person B to pull Person A forwards. Assume that Person A's force is in the positive direction, graph both forces on one set of axis.
Approach: For Person A to neither pull or...
I have read in several books and also in this site that the Newton's Third Law does not hold true for "Action at a distance". Specifically, in the case of Electrodynamics.
Can someone explain to me, what actually happens in the case of electromagnetism? I've read that the action-reaction...
Figure shows a block of mass resting on a slope. The block has coefficients of friction and with the surface. It is connected via a massless string over a massless, frictionless pulley to a hanging block of mass 2.0 kg.
i got this first one: What is the minimum mass that will stick and not...
Homework Statement
Block A and B are connected by a string passing over an essentially frictionless pulley. (Block A is on a horizontal plane, while block B is suspended in the air) When the blocks are moving block A experiences a force of kinetic friction of magnitude 5.7N. If mA= 2.7kg and...
If two objects are stacked in an accelerating elevator what is the force equal and opposite to the normal force on the top object?
I was thinking that it has to be either the force of gravity or contact force between the two objects could it be anything else?
If I push a box (mass of 20kg) with a force of 140N, is my acceleration 2m/s^2 in the positive direction? I cause it to accelerate in the same direction as I'm pushing in, and that accelerates at 7m/s^2, but it reacts with 140N also, so shouldn't it have some acceleration in my direction to...
Homework Statement
A man standing on the ground is subjected to 2 forces : weight and normal reaction force. Do they form an action-reaction pair of forces? (That's Newton's Third Law).
I put yes, but I was wrong. I don't get it. I'm new to Newton's Third Law.
Hello PF members,
I was wondering whether Newtons third law was exclusive to spacecraft thrust; space being empty and without enough particles for a force to push against. That in order to produce thrust in space, you would need to carry the fuel that you plan to eject with you...
Hi. Keppler's third law implicates that the velocity of an object orbiting around our sun is directly dependant on the object's average distance to the sun... Afterall, if the velocity of be more irregular, then no constant would exist.
I realize this probably has something to do with the...
Hi there,
Assume that I push a box with a force of say 50 Newtons and the box moves forward. At the same time, the box pushes me back with the same amount of force. One can argue that hence, the net force here is zero and the box shouldn't move, right?
Compare it to the situation where the...
Hello! My question is about Newton's 3rd law:
Which one of the following is true, according to Newton's laws of motion? Ignore friction.
a. an SUV hits a stationary motorcycle. Since it is stationary, the motorcycle sustains a greater force than the SUV does
b. a semitrailer truck crashes all...
I was just wondering if, according to Newton’s Third Law, every action force has an equal reaction force that acts in the opposite direction, why do these forces not just cancel each other out, resulting in no net force and therefore no motion?
Greetings everyone, I'm new here!
I tried searching the forums for my problem, but most deal more with the common misconceptions, not the question why - if there is such a question. Lately, I've been trying to gain an in-depth look into Newton's work, moreover the third law which has been...
Homework Statement
I just don't understand how to describe how, if a person pushes on a box and the box exerts an exactly equal but opposite force on the person that the person is still able to move the box...
Homework Equations
n/a
The Attempt at a Solution
n/a
I am trying to fully understand Newton's Third Law. I am getting there, but there are a few examples that sort of have me scratching my head for a bit.
Me and a cart are stationary, then I decide to push the cart. I exert a force on the cart and simultaneously, the cart exerts an equal and...
Hello everyone. I think I have almost understood the third one of Newton's motion laws but I have some doubts:
Let us think an inclined plane block located on a surface, there is a box on it and assume there is no friction neither between the surface and block nor between the block and the box...
Homework Statement
Suppose that a comet that was seen in 545 A.D. by Chinese astronomers was spotted again in year 1937. Assume the time between observations is the period of the comet and take its eccentricity as 0.11. What are (a) the semimajor axis of the comet's orbit and (b) its greatest...
Griffiths says "unlike the first two, Newton's third law does not, in general, extend to the relativistic domain."
I don't understand, what is wrong with the following derivation?
So we take it as an experimental fact that momentum is conserved in isolated systems (for clarity, the...
1. Homework Statement
TRIAL 1
A. )
Bag A + 6 stones
Mass (kg) - 0.037 kg
Mass of weight hanger + slotted weights - 210 g/ 0.21kg
Tension 1 (N) - ??
Acceleration (m/s2) - ??
B. )
Bag B + 4 stones
Mass (kg) - 0.08
Mass of weight hanger + slotted weights - 210 g/ 0.21kg
Tension 1 (N) - ...
I found an article on arxiv which basically says that Newton's third law is not verified in certain situations...can anyone please explain more about this in layman terms?? Here's the link:-
http://arxiv.org/abs/1104.5011v1
So, I'm a bit confused... As an example, let's use a box resting on the floor:
I understand the first pair of forces well: Earth pushes the box down with force W, box pulls the Earth up with a force of magnitude W.
Now, the other pair of forces are the normal forces, which my teacher told...
Homework Statement
Blocks X and Y are attached to each other by a light rope and can slide along a horizontal, frictionless surface. Block X has a mass of 10kg and block Y has a mass of 5.0kg. An applied force of 36 N [right] acts on block X.
a) Calculate the action-reaction forces the...
Hello hope you're doing well :smile:
Homework Statement
I'm having a great problem understanding Newton's third law
let's say that we have 2 bodies with masses m1 & m2 where m1>m2
the 2 bodies are connected with a rope body1________body2----->F
a force F is applied on body 2 as shown...
I was looking at a picture (attachment) in a physics website and the following doubt arose:
I previously thought that the weight of the block (gravitational pull of the Earth on the block) caused a reaction force of the table, but now, from what I understand and, please correct me if I am...
I'm a bit confused: Let's take a box standing on a table:
So there are two pairs of force acting on it?
Can anyone help me with the forces on the box?
Thanks,
Peter G.
Tidal effects in the Earth-Moon system are causing the Moon's orbital period to increase at a current rate of about 35 ms per century. Assuming the Moon's orbit around the Earth is circular, to what rate of change in the Earth-Moon distance does this correspond? Hint: differentiate Kepler's...
Homework Statement
After falling from a rest from a height of 30 m, a .50 kg ball rebounds upward, reaching a height of 20 m. If the contact between ball and ground lasted 2.0 ms, what average force was exerted on the ball?
Homework Equations
2.0ms=.002s
The Attempt at a Solution
A brick hits a glass window. The brick breaks the glass, so:
is the magnitude of the force of the brick, greater, less than, or equal to the magnitude of the force of the window?
Newton's third law of motion states that for every action, there is an equal an opposite reaction.
With this...
Homework Statement
three identical boxes, each of weight W, are to be stacked one on top of another against a vertical wall. The lowermost box is in contact with the wall, and the other two boxes are positioned as shown in the diagram. The middle box is pushed into position by the...