Third law Definition and 377 Threads

Is it true that entropy of mixture of twodifferent ideal quantum gases at 0K temperature is equal 0 that is the entropy of mixing is 0 at 0K (two pure gases would have also 0 entropy).

In Newton's third law, do you consider there to be one force or two forces involved? My thinking is that there is only one force which acts equally in magnitude (conservation of momentum) and opposite in direction for each object. However, many sources that I find on the internet claim that...

Homework Statement a truck driver loads two identical untethered crates stacked one upon the other. no sliding takes place. make separate sketches to show the forces acting on each crate when the truck is traveled on a horizontal straight road while accelerating. Homework Equations...

When a car is moving, the engine is transferring Chemical Energy to Kinetic Energy. He is doing work against the force of friction. If the force of friction is 210 N and the engine exerts a pull force for 10 M it transferred 2100J of Chemical Energy from its fuel to Kinetic Energy, considering...

Homework Statement Assuming that the orbits of the Earth, and of Jupiter, around the Sun are circular and given that Jupiter orbits with a radius 5.2 times that of the Earth, calculate the orbital period of Jupiter around the Sun. Homework Equations T2=(4(pi)2/(G*M))*r3 The Attempt...

Homework Statement a sack is in contact with both the base and the vertical back of an excavator scoop. the excavator is moving forward at constant speed in a straight line. make separate sketches showing the forces acting on the sack and the scoop. Homework Equations The Attempt...

Homework Statement A particle of mass 4kg is being towed at a constant speed up a rough plane inclined at 30 degrees to the horizontal by a force 4g N acting parallel to the slope. At the top of the slope the particle moves onto a rough horizontal slope with the same coefficient of friction...

Homework Statement I'm having trouble thinking about Newton's third law pairs and have been trying to find some help searching the Physics Forums archives. Homework Equations I have found alternative explanations for 3rd law pairs involving thrust in an escaped balloon or in a rocket -...

Ah hi there, I would just like to know the environmental applications of Newton's third law? Also fnet= 0; how does an object have constant velocity, is it 0? that's why its constant since its acceleration is 0?? please, I am new.. to physics.. and this forumz.

Hi. I'm having trouble understanding Newton's third law. It states that: To every action there is an equal and opposite reaction. Then howcome if you hit a pool ball with the cue ball, at a straight angle, it'll stop dead. Isn't it supposed to go backwards the same distance as the second ball...

I apologize in advance if this belongs in the Homework section, but my question is not all about one problem and doesn't fit the template. I have some trouble understanding Newton's Third Law. I tried understanding it myself (my teacher is an imbecile who accomplishes almost nothing in every...

Homework Statement A spy satellite is located one Earth radius above the surface of the Earth. What is its period of revolution? ans. 1.5 x 10^4 s Homework Equations I'm trying to use the kepler's constant: k = T^2/R^3 The Attempt at a Solution

Homework Statement In a tug-of-war between two physics types, each pulls on the rope with force of 250N. If both remain motionless, what horizontal force does each exert against the ground? The Attempt at a Solution I can find the tension of the rope, but I am not to sure how to find out...

Homework Statement If a man pulls forward on a sled, and the sled pulls backward on the man with an equal amount of force, how can the man and sled move at all? Homework Equations The Attempt at a Solution

Homework Statement Newton's 3rd law says that a ball exerts as much force on a kid as the kid exerts force on the ball. Is it correct to say the ball does work on the kid? Homework Equations I don't think the ball does work because the kid is not moved by the ball. The Attempt at a...

My teacher just explained to us Newton's Third Law, and one example she used was her pushing against a wall. She stated that the net force would equal zero because the wall was pushing back, but that doesn't make sense to me... What I was thinking was that the force of her pushing was weaker...

Highschool physics student here with a thought experiment I would like some input on. While learning about Newton's Third Law (are reactions are immediate and there is no delay) I had a thought about the speed of light and relativity. Imagine You have a stick with a length of one light-year...

Homework Statement A horizontal force(with respect to the ground) is exerted on a 2 kg box on an incline. theta is 60 degrees above the horizontal. what force Fa is needed to keep the box stationary on the incline? what force does the incline exert on the box?Homework Equations F=maThe Attempt...

Homework Statement Newtons third law tells that if you push a box with 15N force, it pushes back on you with 15N force. How can you ever accelerate this box if it always pushes back with the same force you exert on it? explain briefly

Homework Statement A lead block is suspended from your hand by a string. The reaction to the force of gravity on the block is the force exerted by: (a) the string on the block (b) the block on the string (c) the string on the hand (d) the hand on the string (e) the block on Earth...

Let's say there are two bodies with equivalent mass. The first one orbits the second, and the second one orbits the first. What kind of orbital pattern would result? Assume that the only force considered here is gravity. I know that the centripetal and centrifugal forces are the result of action...

This is not really a homework question, just a question I came up with. If the Earth is pulling, for example, a book with a force of 5 N, that means, due to Newton's 3rd law, that the book is also pulling the Earth with a force of 5 N. Does this mean the total force between them is actually...

Homework Statement A 66.0 kg tightrope walker stands at the center of a rope. The rope supports are 10 m apart and the rope sags 9.00* at each end. The tightrope walker crouches down, then leaps straight up with an acceleration of 8.40 m/s2 to catch a passing trapeze. What is the tension...

I read somewhere that the mass of the sun can be determined using Keplers third law. How is this possible without indulging Newton's law(gravitation) in ?:confused:

I have been thinking about a bar magnet and an infinite wire in free space. The wire is positioned below the north pole of magnet and carries a current. 1) The force from the magent on the wire: Due to the magnetic field, the Lorentz force on the electrons in the wire creates a force on the...

Homework Statement All of the force pairs described below are equal in magnitude and opposite in direction. Which of the pairs are Newton's third-law pairs, which are second-law pairs, and which are neither? 1. A baseball pushes on a window breaking it; the window pushes back on the baseball...

Newtons third law states: "If object A acts on object B with force X, then object B will apply force X on object A" in other words "for every action there is an equal and opposite reaction". Here are my few questions 1) If I apply pull a truck with force X and the truck pulls me with force...

I'm not getting very far with these problems. Don't know what my problem is. Given a circular orbit, the centripetal acceleration is given by the gravitational force between the two stars. I chose the center to be halfway between the stars d/2...

Dear all, A very simple (almost embarrassingly so) question here, but I just want to double-double check what is going on. Kepler's Third Law states for a planet of mass Mp orbitting star of mass M* at a semi-major axis $a$ with a period P, that: [P/(2pi)]^2 = a^3/G (Mp+M*) Now what I want...

hi am new here ... and sorry for my weak English i have a question and a problem in physics that i need to know it's solution i will give you the main idea without numbers and you can assume any numbers that you find it suitable for the problem... the problem say: if a small ball is...

The are at least two different formulation of third law of thermodynamics: (1) it's impossible to cool a body to absolute zero by any finite process, (2) as a system approaches absolute zero, all processes cease and the entropy of the system approaches a minimum value. I don't know why they...

Hello everyone, Ok I'm no longer worried about why Newton's third law is occurring. Doc Al advised me in the last thread to look at some action reaction pairs instead, and I think that is what I needed to do. Ok I'm having difficulty understanding Newton's third law when two objects are...

in Newtons third law of motion every action has equal and opposite reaction so my question is that when block hits another block the blocks exert equal force on another so why they move they had to stop immediately.

Could you please also tell me where (else) the third law fails?

Hello; I am a little confused here. A friend asked me that, due to Newton's Third Law of Motion, for every force there is an equal and opposite force. Therefore, why is it, for example, that when we throw a ball up into the air, it moves upwards at all, if the force exerted on the ball...

Homework Statement My teacher puzzled me in the beginning of the year by saying that one cannot possible hit a falling feather with 200 Newtons because a falling feather doesn't have 200 Newtons to hit you back with. (Newton's Third Law) Homework Equations None The Attempt at a...

Homework Statement If the forces in Newton's third law are equal and opposite, they cancel, and thus nothing can ever accelerate, so the law is absurd. Homework Equations Argue why this isn't true. This is from my textbook, a very strong argument. The Attempt at a Solution Hey...

Homework Statement A train consisting of two cars pulled by a locomotive experiences an acceleration of 0.33m/s^2 [fwd]. Friction is negligible. Each car has a mass of 3.1 * 10^4 KG. a. ) Determine the force exerted by the first car on the second car. b. ) Determine the force exerted by...

Hi, I´m doing a school project about the history of physics and I think I could use your help. When we study Newton´s laws in school there´s often no justification as to why they are the way they are. Particularly, the third law just seems Newton´s wild guess. There seem to be no good...

Right now I am taking a classical physics course and find myself struggling with Newton's Third Law, which states that for every action there is an equal and opposite reaction. I am struggling to interpret this in a way such that I can still accept movement of objects. If I attempt to slide...

Homework Statement This is more of a concept problem than one of number manipulation. I was wondering, if when a horse pulls forward on a cart with a force of 500 N and the cart pulls back with a force of 500 N by Newton's 3rd Law, how does the cart move if the net force is 0? Homework...

I can't understand the significance of Newton's third law. What would happen if there were no reaction forces?

Hello! Here is an equation that i sometimes use in calculating enthalpy of reaction aA+bB=cC+dD. a,b,c and d are stoechiometric coefficients, A,B,C and D are chemical compounds in reaction. They say that is an other form of the third law of thermodynamic, can one guide me please to derive it...

Homework Statement A box of mass m2=3.5 kg rests on a frictionless horizontal shelf and is attached by strings to bodes of masses m1 = 1.5 kg and m3 = 2.5kg. Both pulleys are frictionless and massless. The system is released from rest. After it is released, find (A) the acceleration of each...

Homework Statement An orbiting satellite stays over a certain spot on the equator of (rotating) Pluto. What is the altitude (in km) of the orbit (called a "synchronous orbit")? Homework Equations r = [(G*M*T^2)/4pi^2]^(1/3) h= r-radius of pluto The Attempt at a Solution I have...

1. 2. On a horizontal road, a small sedan is pulling a large station wagon that has run out of gas. While the sedan is speeding up to high way speeds. A. The sedan pulls harder on the station wagon than the station wagon pulls on the sedan; otherwise there would be no acceleration. B...

i don't quite get Newton's third law... :( It sounds simple enough, F12 = -F21. However, I'm getting that mixed up with the second law now (ie. if there is a net F on the system, there will be acceleration). For instance, say that there's a box, and the "F" vector is pointing to the right...

Homework Statement A 1.0 kg physics book is on a 20 degree slope. It is connected by a string to a 500 g coffee cup dangling at the bottom side of the incline. The book is given a push up the slope and released with a speed of 3.0 m/s. The coefficients of friction are us = .50 and uk = .20...

Homework Statement This isn't a homework question, but I thought this would be the appropriate place for the thread. I am having trouble explaining Newton's Laws to my friend. His confusion lies in the fact that the second Law F=ma does not equate to the sum of Forces in The third Law. Ex. A...

I can't prove the Newton's third law. Please tell me how to prove the Newton's third law. Thanks.