Law Definition and 999 Threads

Homework Statement Huge suspension bridges are build with the Earth's roundness in mind. The two towers are plumb line straight up and down and yet, because of their colossal size, they are a bit further apart at their tops than they are at their base. So, how can we calculate what this...

Simple Law of Cosines Question Huge suspension bridges are build with the Earth's roundness in mind. The two towers are plumb line straight up and down and yet, because of their colossal size, they are a bit further apart at their tops than they are at their base. So, how can we calculate...

Homework Statement A 2,300 kg truck pushes a 2,500 kg SUV, and they both move at 3.75 m/s2. I am to find the force that the SUV exerts on the truck. Homework Equations F=ma The Attempt at a Solution I solved this problem already, it was just taking the acceleration I had found (3.75) and...

Homework Statement A circular coil with radius a is connected with an equilateral triangle on the inside as shown in the figure below. The resistance for each section of the wire is labeled. A uniform magnetic field B(t) is pointing into the paper, perpendicular to the plane of the coil. B(t)...

Where can I find direct experimental evidence that Snell's law is correct for at least three of the typical spectral colours (say RGB). Thank you.

Homework Statement Matt Damon is stuck on Mars. He needs to get o the planet and into orbit to rendezvous with the rescue team, which will be orbiting the planet at the same radius as Phobos, one of Mars’s moons. His goal is to determine what his take-of speed should be so that he makes it into...

According to this pdf http://www.springer.com/cda/content/document/cda_downloaddocument/9783319011066-c2.pdf?SGWID=0-0-45-1429331-p175291974 Newton's second law is not invariant under Lorentz transformations. To find out the part that says so, use CTRL+F and type "Newton"; it's the first result...

I assigned a question: Explain the physics mechanism that results in the buoyancy force. Some students replied: The floating object is interacting with the water. Therefore it exerts a downward force on the water. The water then exerts an upward force on the object due to Newton's Third Law...

Homework Statement Suppose an infinitely long wire carrying current ##I=sin_0(\omega t)## is a distance ##a## away from a equilateral triangular circuit with resistance ##R## in the same plane as shown in the figure. Each side of the circuit is length ##b##. I need to find the induced voltage...

Homework Statement I just have a general question about Guass's Law and the cylinders above. I don't really understand what the difference is between the 2 cylinders? They are both charged, but one of them does not have an electric field inside the cylinder because it a conducting...

Do alternators obey Ohm’s law? The alternator output voltage is proportional to the rotor excitation current. When reducing rotor excitation, the output voltage drops and the load resistance stays constant. Can why still use ohm law to determine the output current. Example alternator 480 v / 4...

When fired, a slug's acceleration down a barrel produces an equal backward force. I get that. What I DON'T get, is why there is no rebounding force counter to a slug's impact by the material being struck? The material/molecules simply get impacted and pushed via the force generated. Why is there...

Homework Statement An infinitely long wire carries current I=I_0sin(wt). A distance a from this wire is an w by l loop with resistance R with induced voltage V and induced current i. Find the induced voltage and current in the loop. Homework Equations Faraday's law is given by \varepsilon =...

I have attached the problem and my attempt at solving it, there is a strange equation under the data analysis section that I do not understand. I'm and suppose to calculate a theoretical value for a slope and compare it to the one I have.

If I have a superball and a tomato of the same mass in my hand, and I let it go. The only force acting on my superball and tomato is gravitational force. F=ma, they have same mass so they will hit the bathroom scale with the same force. According to Newton's third law, the bathroom scale will...

Is there a mathematic model for the first law of dynamics? If no, do you think that this law can be modellized with maths?

Homework Statement Assume a uniform hollow cylindrical copper tube with the following parameters: Inner radius = R0 Outer Radius = R1 Length = L1 (Length > Outer Radius) Mass = M1 Now assume a cylindrical permanent magnet with the parameters: Length = L0 (L0 < L1) Mass = M0 Magnetic...

I am a little confused when I try to use Ampere's law to calculate the B field from a balanced three-phase system. Consider the following, shown in the picture below: Lets say I want to calculate the value of B at a distance r (radius of my Amperian loop), the value of r is big enough so that...

I have come up with a bit of a problem in my head regarding Newton's first law. If any of you could help me solve it that would be much appreciated. So if you throw a tennis ball (or any object really), and you throw it into an infinite expanse of nothing but void, it will travel forever, or...

Homework Statement "Fluid will leak out of a hole at the base of a cylindrical container at a rate proportional to the square root of the height of the fluid's surface from the base. If a cylindrical container is initially filled to a height of ##h(0)=12 in.##, and it takes one minute for the...

Homework Statement In one of the most common examples of Lenz's Law a magnet is dropped inside a copper tube and due the induced emf and the eddy currents generated in the copper tube the magnet falls through it with constant velocity. The external force that the eddy currents oppose is...

50 cm^3 of nitrogen combine with 150 cm^3 of hydrogen gas to form 100 cm^3 of ammonia. Does this agree with gay lussacs law of combing volumes?. Explain your answer. i feel the answer is yes but I can not give the reason why?

Hello, everyone, I was looking at this video () and I need to make a simulation for Stefan Boltzmann law calculating its constant. I didn't understand few things. In the video, it shows that Stefan Boltzmann law is R = e*sigma*T^4vand then says that rate of net heat transferred ΔQ/Δt =...

Imagine we have a box suspended to the ceiling by a rope of negligible mass, the net force looks like: ∑F=T-Fg=0 T=Fg where T and Fg are equal in magnitude but opposite in direction. If we cut the rope, the box is in free fall and ∑F=Fg, and this equation is similar to T=Fg but Fg and ∑F have...

I've learned that first thermodynamic law for some open system is in the form of: where total change of system energy ##\frac{\partial E}{\partial \tau }## is equal to the transferred heat and work. Total change of system energy ##\frac{\partial E}{\partial \tau }## is equal to the energy...

Hi everyone! I've just signed up as I thought it would be very useful to hear from other people who are currently studying or have graduated and are thinking about career options. I recently graduated in physics from a Russell Group university in London and I am looking forward to what is next...

Homework Statement Two small spheres of 15 g each are suspended from a common point by threads of length 35 cm. Each thread makes an angle with the vertical of 20 degrees. Each sphere carries the same charge. Find the magnitude of this charge. (The correct answer is: 0.58 μC)Homework Equations...

Hey I was just practicing Gauss's law outside a sphere of radius R with total charge q enclosed. So I know they easiest way to do this is: ∫E⋅da=Q/ε E*4π*r^2=q/ε E=q/(4*πε) in the r-hat direction But I am confusing about setting up the integral to get the same result I tried ∫ 0 to pi ∫0 to...

Homework Statement Show with an example whether Magnetic Force follows Newton's 3rd Law. Homework EquationsThe Attempt at a Solution Let's consider the following system at time t. ##\vec B ## due to moving q1 at q2 i.e. ## \vec B_1 ## is along ## \hat y ## direction. So, the force on the...

Homework Statement In Newtonian theory the gravitational potential Φ exerts a force F = dp/dt = −m∇Φ on a particle with mass m and momentum p. Before Einstein formulated general relativity, some physicists constructed relativistic theories of gravity in which a Newtonian-like scalar...

Homework Statement A.[/B] Suppose I have a block of mass 'M' that is attached to a wall via spring of coefficient 'k' , the spring has rest length Xo . Suppose I look at the problem at some time 't' such that the spring is being compressed and the block moves left ( moving towards x = 0 ) ...

http://www.nat.vu.nl/~tvisser/nonexponential.pdf I always thought that an unstable system will decay exponentially but I recently learned that it obeys the quadratic law in the short time and power law in the long time. Can somebody tell me the equation that governs the quadratic law and power law?

Homework Statement Two fully equal sphere's of lead are placed next to each other so that the gravitational force between sums up to 10N. Calculate mass and radius of the two sphere's. F=10N , ρlead=11300kg/m2 Homework Equations F=gm, F=GMm/r2 , V=4πr3/3 , ρ=m/VThe Attempt at a...

Can someone clarify this for me-- how is the motion of the center of mass unaffected by internal forces, as is stated towards the end of the paragraph in the picture I've provided. It seems to me that motion of the center of mass directly affected by these internal forces. Specifically, the...

Hi, I've got a question regarding application of the Biot-savart law along finite wire. There is a great explenation of this problem in the MIT paper but this does not cover one case. 1. Homework Statement My question is: does the equation defining magnetic field in point P(x,y) also applies...

Homework Statement A block of mass M is hung on a vertical spring. We have to find spring constant k, x (displacement from mean position) given. Homework Equations 1/2kx^2 = mgx mg=kx The Attempt at a Solution When i conserve energy, 1/2kx^2=mgx ⇒ k= 2mg/x But when i use mg=kx, I get k=mg/x...

Homework Statement After a mishap, a 76.0-kg circus performer clings to a trapeze, which is being pulled to the side by another circus artist, as shown here. Calculate the tension in the two ropes if the person is momentarily motionless. Include a free body diagram in your solution Homework...

Homework Statement "In an early attempt to understand atomic structure, Niels Bohr modeled the hydrogen atom as an electron in uniform circular motion about a proton with the centripetal force caused by Colomb attraction. He predicted the radius of the electron's orbit to be 5.29x10^(-11) m...

Homework Statement A small spring with a force constant of 72 N/m is held vertically and then stretched 16 cm. A 1.6kg mass is attached to it and then released. Calculate the acceleration of the mass at the moment of release. Homework Equations F = ma, Ee = 1/2kx^2 The Attempt at a Solution...

Hi guys, can you tell what is the fourier's law?

In a transformer, the primary coil has a current running through it which creates a magnetic field. Then this field induces a current in the secondary coil. That induced current creates a magnetic field exactly opposite the inducing magnetic field. This might be an obvious question, but that...

Homework Statement In the chapter about differentiation there is this question: Homework Equations Cosine rule: $$a^2=b^2+c^2-2bc\cos\alpha$$ $$\cos(\alpha-\beta)=\cos\alpha\cos\beta+\sin\alpha\sin\beta$$ The Attempt at a Solution $$a^2=b^2+c^2-2bc\cos\alpha$$ $$d^2=e^2+c^2-2ec\cos\beta$$...

New Florida law let's any resident challenge what’s taught in science classes. https://www.washingtonpost.com/news/speaking-of-science/wp/2017/07/01/new-florida-law-lets-any-resident-challenge-whats-taught-in-science-classes/?utm_term=.0104dd426ae7 I'm wondering if soon teaching actual science...

Hello, 1- IF we have an object has 200 kg and we also have a machine has 5 kg and pushes that object with force of 600 n , in Newton third law it must be another force =-600n then : the acceleration of the object must be 3 m\s^2 and the acceleration of the machine is 120 m\s^2 , Am I wrong...

(##c = 1##) So: ##v = \dfrac{u + w}{1 + uw}##. If the thing with speed ##u## happens to be light, then the equation still works: ##v = \dfrac{(1) + w}{1 + (1)(w)} = 1##. And the inverse formula still works, too: ##u = \dfrac{v - w}{1 - vw} = \dfrac{(1) - w}{1 - (1)w} = 1## But is this...

Homework Statement A charge of -30 μC is distributed uniformly throughout a spherical volume of radius 10.0 cm. Determine the electric field due to this charge at a distance of (a) 2.0 cm, (b) 5.0 cm, and (c) 20.0 cm from the center of the sphere. Homework Equations Eq. (1): E⋅A=qenc/ε Eq...

Does a system with zero entropy represent the thermal equilibrium at some temperature = 0K? Does the second law of thermodynamics entail that the system will eventually evolve to higher entropy? e.g. a system of 7 magnetic dipoles of paramagnetic spin-1/2 particles in an external magnetic...

Consider the first paragraph of this paper - https://arxiv.org/abs/gr-qc/0611004: A fundamental problem in thermodynamic and statistical physics is to study the response of a system in thermal equilibrium to an outside perturbation. In particular, one is typically interested in calculating the...

Hi, From the first law of thermodynamics it follows: Cp * (δT/δt) = (δQ/δt) where Cp = specific heat capacity, T = temperature, Q = heat, t = time From this formula, you would derive that temperature keeps on increasing as long as dQ/dt > 0. But if you, for example, look at the idealized...

Homework Statement An ideal gas with Cv = 5/2R, and γ = 1.4 starts at a volume of 1.5m3 , a pressure of 2.0×105Pa, and a temperature of 300K. It undergoes an isobaric expansion until the volume is V , then undergoes an adiabatic expansion until the volume is 6.0m3 , and finally undergoes an...