Second law Definition and 479 Threads

Homework Statement Influenced by certain force, cart moved from place and driven 0.5 meters distance. When 200grams weight was placed on cart it moved 0.3 meters during the same period of time. Calculate the mass of the cart.

Homework Statement Newton’s second law says F->net=ma->. So is ma-> a force? Explain. -> is a top bar arrow. Homework Equations F=ma or Fnet=ma The Attempt at a Solution (F) is a force and (m) is mass and (a) is acceleration. I don't really know what else this question is asking...

if second law of thermodynamics is emergent and not fundamental, in the same way color is emergent but atoms themselves are colorless, then perhaps black holes do not carry entropy or can violate the second law? second law of thermodynamics is shown to exist in the macroscopic world but how do...

Mod note: The link in the original post contained a link to a crackpot, anti-evolution website (against our rules) that discusses a rejected paper (also against our rules). This link has been removed. Here's a link to Retraction Watch that covers the same (retracted) paper...

I've searched a little bit and found that I can derive kepler's third law from Newton's law of gravitation. That's okay. But I want to deduce kepler's second law too: "An imaginary line joining a planet and the sun sweeps out an equal area of space in equal amounts of time". I know it's possible...

I have been working on modeling the orbit of a satellite using Kepler's second law of planetary motion, and I have gotten to a point that is really quite bothersome to me. Essentially, my problem boils down to solving this equation for θ (angular position of the planet from the focus of the...

Does QM uncertainty cause/explain the Second Law of Thermodynamics? If so is entropy the contribution of hidden variables, to our classical world? How about negentropy? http://arxiv.org/abs/quant-ph/0605031 Irreversibility in Collapse-Free Quantum Dynamics and the Second Law of Thermodynamics...

Hello, I am confused by the momentum version of Newtons second law... So we know \bar{F}=m\bar{a}=m\left(\frac{d\hat{v}}{dt}\right) and that \bar{\rho}=m\bar{v}=m\left(\frac{d\bar{x}}{dt}\right) so is \frac{d\bar{p}}{dt}=m\frac{d\left(\frac{d\bar{x}}{dt}\right)}{dt} What I mean is this...

Homework Statement In a laboratory frame of reference, an observer notes that Newton's 2nd Law is valid. Show that Newton's 2nd Law is also valid for an observer moving at a constant speed, small compared with the speed of light, relative to the laboratory frame. Homework Equations dx'/dt =...

We all know that f = m*a. But why can't we write this as f = m * s/t^2 ? I know this is wrong. But what is the reason?? Need opinion on this. Thankyou.

Homework Statement If I have shot an arrow, would that arrow speed slow down due to air resistance? If so, would that mean that the the acceleration would be de-accelerating? Homework Equations f = ma The Attempt at a Solution This isn't a a homework problem, this is just something I was...

is there any derivation of Newton second law?

Homework Statement While moving in, a new homeowner is pushing a box across the floor at a constant velocity. The coefficient of kinetic friction between the box and the floor is 0.41. The pushing force is directed downward and an angle θ below the horizontal. When θ is greater than a...

Homework Statement Homework Equations F=ma, Fr = μN The Attempt at a Solution 1kg(1m/s^2) = 1N Fnet = (x) - 1.18 1N = x - 1.18 x = 2.18N 2.18N/9.81m/s^2 = 0.223kg I know this is not right because I was told that in my calculations Fnet and Fr go in the same direction. Also I didn't use...

Homework Statement An airplane goes into a turn 3.6km in radius. If the banking angle required is 28 degrees from the horizontal, what is the plane's speed? Homework Equations Newton's Second. The only forces acting on the plane are gravity and the normal force. This isn't given in the...

1. A 92 kg water skier floating in a lake is pulled from rest to a speed of 12 meters/second in a distance of 25 meters. What is the net force exerted on the skier, with the assumption that his acceleration is constant?2. Force = Mass x Acceleration3. As far as I know, from using the equation...

What does the P-V diagram for a cycle that violates the Kelvin Planck statement of the second law of thermodynamics look like? Would you say we cannot draw such a diagram BECAUSE of the second law?

Homework Statement A 2.60 kg block is initially at rest on a horizontal surface. A horizontal force F→ of magnitude 7.39 N and a vertical force P→ are then applied to the block (see the figure). The coefficients of friction for the block and surface are μs = 0.4 and μk = 0.25. Determine the...

Homework Statement Given that: theta_dot = 6 rad/sec m_A = 0.8kg u_k = 0.40 The problem also mentions that movement is at a constant angular rate so I think that means: r_doubleDot = 0 theta_doubleDot = 0 Lastly, at an instant: r_dot = 800mm/sec = 0.8m/sec 2. Homework Equations...

THIS THREAD HAS BEEN MOVED FROM ANOTHER FORUM BECAUSE IT IS HOMEWORK. BUT THERE IS NO TEMPLATE. Hi everyone, The problem gives that a particle moves in a circle with angular velocity ω. I know that r×ω=v, which is the velocity of the particle. However, I am told to differentiate and find τ=Iα...

So I was wondering how did Newton himself state his second law. One account I've read says that he first expressed it in the form that we refer to as impulse and momentum i.e. FΔt=mΔv. Today I was told that Newton never even wrote F=ma, and that the expression a=F/m is a much "Better" way of...

Homework Statement So I am stuck on this homework problem. I understand the general direction I have to take, but my algebra and physics aren't good. Here's the problem: A simple Atwood's machine uses two masses, m1 and m2. Starting from rest, the speed of the two masses is 10.0 m/s at the end...

Homework Statement Hello the text is in swedish but ill try my best to translate, What it says is: Determine the resultant force on the moon with regard to thr gravitation force from the sun and the Earth when it's in this position shown in the figure [ picture http://m.imgur.com/AfJOVZo ] J...

Homework Statement Here's the problem: A particular racecarcan cover a quartermile track (402m) in 6.40s starting from standstill. Assuming that the acceleration is constant, how many "g's"(all i know is that it means accleration due to gravity) does the driver experience? If the combined mass...

hi , will change first law efficiency proportional to second law efficiency? for example in gas turbine cycle, how change? other equation: hi , will change first law efficiency proportional to second law efficiency? for example in gas turbine cycle, how change? other equation: How is the...

In the derivation on Wikipedia, it says the following ## \frac{dv}{dt}=\frac{dv}{dx}\frac{dx}{dt}=\frac{dv}{dx}v = \frac{d}{dx}[\frac{v^2}{2}] ## How do they go from the second to last to last equation? I've been trying to understand, but I think I'm just looking over something incredibly simple.

I'm reading Halliday's chapter or rigid body rotation. In the derivation of Newton's second law for rotation, it is assumed that the object is hinged about some axis ( the connection would be a frictionless pin). The law is derived for such a connection, but is later applied to objects that...

Hi all I hope you can help me with the statistical origins of the Second Law. I cannot find anything that mathematically proves that order from disorder is impossible only improbable. Leading me to think that a system (Kelvin engine) that allows order to be created from disorder (work from...

Homework Statement (This is a problem I made up, so if the problem is with the problem, let me know.) A 500N ball is being pushed down a carpeted decline of 24° to the horizontal. It starts from 1 m/s and ends the 20 foot (6.1 m) decline at 32 m/s. What is the coefficient and force of kinetic...

Very stupid question, but I am writing out my problem and need this formula; in typed symbols, so I can copy and paste it into my document. Like √ Hope that makes sense... Thanks!

Hello, I am a second year undergrad student majoring in Astronomy and Computer Science. I am having a hard time with my physics courses for the following reasons: 1) SmartPhysics is the text we use (if you can call it a text...). Basically it is an online HW and "pre-lecture" system that...

Renee is on Spring Break and pulling her 21-kg suitcase through the airport at a constant speed of 0.47 m/s. She pulls on the strap with 120 N of force at an angle of 38° above the horizontal. What is the normal force and the total resistance force (friction and air resistance) experienced by...

Homework Statement A 9 kg object is subjected to two forces, http://www.webassign.net/images/Farrowbolditalic.gif1 = 7 N i - 4 N j and [PLAIN][PLAIN]http://www.webassign.net/images/Farrowbolditalic.gif2 = 7 N i - 9 N j. The object is at rest at the origin at time t = 0. (a) What is the...

Homework Statement Homework EquationsThe Attempt at a Solution I'm not sure if their are frictional forces on the cart and the mass m. Also do I have to somehow get the length of the bar involved ?, not sure how to do that. Also is their a tension acting on the bar ?

With my understanding of Newton's second -- if I am going to use it to solve a problem, I would need to write ALL velocities in the system with respect to the lab frame (inertial rest frame) -- correct? Thanks, Chris

Homework Statement A 4 kg book sinks a distance of 5m in the ocean starting from rest. The volume of the book is 0.00266666666666667 m^3. We assume the velocity of the Earth is zero during the whole process, and gravity and the bouyance force are the only interactions of the book. (Note...

Homework Statement I am to prove that a solution to the differential equation Fick's second law is valid by substitution. Homework Equations Fick's second law: \frac{\partial C}{\partial t} = \frac{\partial}{\partial x} \left( D \frac{C}{\partial x} \right) Solution to Fick's second...

Two vectors acting on a moving object that has a mass of 27kg.One force has a magnitude of 12 N and points due south, while the other force has a magnitude of 17N and points due west,find acceleration of the object? Calculate the resultant force acting on the object: RF² = 12² + 17² RF² =...

Does this solution mean anything ?

[SIZE="4"]Definition/Summary The second law has various forms. I shall give these here then show how they are logically connected. Entropic Statement of the Second Law: There exists an additive function of thermodynamic state called entropy which never decreases for a thermally...

[SIZE="4"]Definition/Summary Net force = rate of change of momentum (= mass times acceleration of the centre of mass, if the mass is constant) Net impulse = change of momentum These are vector equations, so they apply to each direction individually The rotational versions are: net...

I know a high school student who has this question. My first thought was that it does not hold if the mass is changing with time. I was thinking of the situation of a snowball rolling down a mountain picking up more snow as it rolls to the bottom. There is obviously mass gained so does Newton's...

We know that a steam power plant is basically a heat engine with steam as the working fluid. According to the second law of thermodynamics a heat engine must operate between two thermal energy reservoirs one at a higher temperature(source) than the other(sink) to produce net work in a...

In Heaviside's Electromagnetic Theory (1895) he says that "The second law of thermodynamics itself needs to be established from electromagnetic principles, assisted by the law of averages..." I attempted to Google whether or not anyone has derived the second law via electricity and magnetism...

Hello there. New here. I have read and tried to understand the Kelvin Plank statement of the second law. Essentially, it would imply, it is impossible to convert a given quantity of heat completely to work. Why is it so? I mean, what is the justification for this? I am ready to...

Homework Statement A 6.7-kg box is being lifted by means of a light rope that is threaded through a single, light, frictionless pulley that is attached to the ceiling. (a) If the box is being lifted at a constant speed of 2.0 m/s, what is the power delivered by the person pulling on the rope...

Homework Statement I'm trying to bridge F =ma to m/2(dv2/dx). It was shown in the course book I have but there's a huge disconnection in the steps. The Attempt at a SolutionF =ma = m.(dv/dt) = m(dv/dx . dx/dt) = mv(dv/dx). Where do I take it from here?

Homeopaths assert that dilution of a medicinal substance in a water -alcohol mixture, followed by forceful shaking (called "succussion") would create a memory of that substance in the solution. Critics argue that shaking of liquid water is unable to create macroscopic order, as this would...

Homework Statement A cable is being used to lift a 350 kg piano into a helicopter. The cable can exert a maximum force of 5000 N without breaking. What is the maximum acceleration that the cable can give to the piano? Homework Equations w=mg The Attempt at a Solution w=? a=...

For those who read carefully the paper by Esther Hänggi and Stephanie Wehner: "A violation of the uncertainty principle implies a violation of the second law of thermodynamics": 1. Can you elaborate how extra work can be extracted if the UP is violated? 2. Does the paper implies that...