Conservation Definition and 999 Threads

Homework Statement [/B] Two blocks are connected by a string that passes over a massless, frictionless pulley, as shown in the figure. Block A, with a mass mA = 4.00 kg, rests on a ramp measuring 3.0 m vertically and 4.0 m horizontally. Block B hangs vertically below the pulley. Note that you...

I have to design a track for a skate boarder that is 50% efficient (friction must be present) from the start of the skater's drop-in, to his furthest point along the track. My skater's mass will be 75kg efficiency=energy output/energy input x100% I am not really sure where to go next and how...

This problem assumes working in natural units where ##c=1##, and using the Minkowski metric where the time component is positive and the space ones negative (as I know the opposite convention is just as commonly used). EDIT: I had intended to display 4-vectors as bold and the 3-vectors with the...

Homework Statement A 4.0 kg block starts at rest and slides a distance d down a frictionless 35.0 incline, where it runs into a spring. The block slides an additional 16.0 cm before it is brought to rest momentarily by compressing the spring, whose spring constant is 429...

I have two balls spinning with v1, omega1 and v2, omega2. They collide elastically with no tangential slip, resulting in new values for v1, omega1 and v2, omega2. I have the two components v1 & v2 figured out in the plane of contact, where angular momentum does not come into play. But I am still...

< Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown >[/color] My question is from an exam in analytic mechanics. The question was about an object sliding on inclined plane, the plane's angle is constant, and the plane is free to move along X axis...

Homework Statement A particle of mass M and 4-moment P decays into two particles of masses m1 and m2 1) Find the total energy of each particle (lab frame). 2) Show that the kinetic energy T1 of the first particle in the same reference frame is given by $$T_1= \Delta M (1 - \frac{m_1}{M} -...

Why is "generation number" or "family number" conserved among leptons, but not among quarks? Why does a positive kaon decay into an antimuon and a muon neutrino? Why doesn't it decay into an antimuon and an electron neutrino? The anti-strange (generation 2) flavor then becomes anti-muon flavor...

Homework Statement [/B]Block 1 of mass 3.0 kg is sliding across a flooe with speed ##v_1=2.00 \frac m s## when it makes a head-on,one dimensional,elastic collision with initially stationary block 2 of mass 2.0 kg.The coefficient of kinetic friction between the blocks and the floor is...

Homework Statement http://tinypic.com/r/10f5ni8/9 http://[PLAIN]http://i66.tinypic.com/10f5ni8.png Homework Equations I have a problem understanding this problem. It asks for the velocity of block A when block B is moved 300mm/s to the right. The equation for the cord length is given as...

Homework Statement A ##10.0kg## block falls ##30.0m## onto a vertical spring whose lower end is fixed to a platform.When the spring reaches its maximum comprassion of ##0.200m##,it is locked in place.The block is then removed and spring apparatus is transported to the Moon,where the...

Homework Statement Theres a pic. Homework Equations ##W_{friction}=W_{fr}=Δ(ME)## ##U_{spring}=U_s=\frac 1 2kx^2## The Attempt at a Solution I found (a) using ##W_{fr}=Δ(ME)## which ##v=7,4 \frac m s## For (b) I wrote;##\frac 1...

We know lepton conservation law, that means multiple neutrinos can not be consolidate to big single neutrino. But photon is boson not lepton, no need of conservation, does that mean it is possible to combine or fuse a bunch of photons into ONE big photon, or say, more energetic photon, i.e...

Homework Statement I am happy to re-write the question, but I'm just leisurely working through a list of problems I found online, so here is the link (with picture). http://web.mit.edu/2.25/www/5_pdf/5_01.pdf Homework Equations Cons of Momentum Cons of Mass The Attempt at a Solution a) I...

I just recently learned about Leonard Susskind's work on conservation of information. From what I've read and from his lectures, conservation of information and the holographic principle are based on the reversibility of physical laws. Reversibility in turn implies determinism, so if...

Hello, I have 2 questions regarding similar issues : 1*) Why does one say that parallel transport preserves the value of dot product (scalar product) between the transported vector and the tangent vector ? Is it due to the fact that angle between the tangent vector and transported vector is...

1. In the figure shown , a ball of mass m collides perpendicularly on a smooth stationary wedge of mass M , kept on a smooth horizontal plane. If the coefficient of restitution is e , then determine the velocity of the wedge after collision. https://postimage.org/][/PLAIN] Given mass of ball...

Hello, This has been bugging me for some time now, so I would be interested to see what I have been missing so far. Imagine a single ray of light (made up of many photons) hitting a perfectly non-absorbing (for this wavelength of light) spherical dielectric object, which has finite mass. The...

I have a ball and the wind blows on it. Could I find the initial velocity of the ball from conservation of momentum? m_air * v_air = m_ball * v_ball v_ball = (m_air * v_air) / m_ball What would you put for m_air?

Homework Statement A uniform solid sphere of radius R, rolling without sliding on a horizontal surface with an angular velocity ωo, meets a rough inclined plane of inclination θ=60°. The sphere starts pure rolling up the plane with an angular velocity ω. Find the value of ω. Homework...

There are irreversible logic gates, are there not? Gates who's outputs don't preserve information about their inputs, no? Or take for example computer parts that crunch numbers. If you know the answer to a calculation is 12 but that's all you know, then you can't figure out whether the...

Conservation of energy Is the law of conservation of energy absolute? If so, doesn't it follow that all the energy of the big bang came from somewhere? That the energy of our universe must predate the big bang? Isn't that circumstantial evidence of the validity of string theory which...

Are exothermic reactions violation of law of conservation of mass , because energy and mass are equivalent? Please clarify!

Homework Statement (This is a problem I myself created, so it may sound a bit trivial/stupid.) A particle of mass m in the xy plane has velocity v and a radius vector r with respect to some origin. After some time Δt, the same particle has velocity v and a radius vector r' with respect to the...

I often hear that a superconductor can hold a current indefinitely, I have a thought experiment which relates to this claim. Consider a closed square loop of superconducting wire, this wire carries some current. Will the electrons in the circuit transfer momentum and energy to the metal lattice...

How can we prove the law of conservation of mass ? I said prove not the verification, how lavoiser decided that yes this law is followed by every chemical reaction, is there a proof

Homework Statement There are two elastic "superballs" of mass M and m placed on top of each other with a smal distance. The lighter ball of mass m is on top of the bigger ball of mass M. The balls are released from a height h and have velocity u when they hit the ground. Prove that the top ball...

I'm having promblem with b. I checked the solution, but I did'nt understand the logic. Kf+Ugf+Usf = Ki+Ugi+Usi Usf= 0, Ki=0, Ugf= 0 I understand the logic's why they are equal to 0. I don't understand why final potential of spring (Usf) is equal to zero? ------------------ Now, I got...

Homework Statement 2. Homework Equations [/B] Inital energy=Final energy K.Ei+P.Ei=K.Ef+P.Ef The Attempt at a Solution

Homework Statement An object of mass m starts from rest and slides a distance d down a frictionless incline of angle (theata). While sliding, it contacts an unstressed spring of negligible mass as shown in the Figure below. The object slides an additional distance x as it is brought momentarily...

Homework Statement A .01kg bullet is fired into a 1.2kg block hanging from a 1m wire. The bullet exits the block with a speed of 200m/s and the block swings to a height of .2 meters. What is the original velocity of the bullet? What percentage of the original energy of the bullet is no longer...

Homework Statement Imagine that you are standing on the edge of a cliff looking out over the vista… a sudden gust of wind nudges you off balance and you start tilting out over the edge of the cliff…. Yikes! You start wind milling your arms to regain your balance. A) do you rotate your arms...

Is the law of conservation of momentum valid in non isolated system . What is an isolated system? My teacher confuses me that the law is valid in an non isolated system . They even say that when we say about the isolated system (meaning they are present ) we do not consider the air resistance...

Consider two objects, "A" and "B", each having mass 1kg. Object "A" moves downward towards object "B" and collides with the extended arm of object "B". Let's say for the sake of argument that during this collision object "A" lost one unit of momentum and 0.5 joules to object "B" (This value does...

Question says" When a car comes to a normal stop its momentum is not conserved. Does this violate the principle of conservation of momentum? Explain. What happens to the car's kinetic energy?" My question is why momentum is not conserved when a car comes to a normal stop?

I am not a student. This is not a homework question. I am a 64 year old man who wants to understand a principle of physics. Suppose there is a large block of matter, designated as m2, which lies on a flat surface that initially is at rest. At some point in time a small block of matter...

Homework Statement A 45 kg steel ball is projected vertically with an initial speed of 280 m s . While the ball is rising, 8.5E5 J of heat energy are produced due to air friction. What is the maximum height reached by the ball? Homework Equations Ek = 1/2mv^2 Ep = mgh The Attempt at...

Homework Statement A 10 kg initially at rest is pulled 13m across a floor by a 50N force. if friction does 380J of work over this distance, what is the block's final velocity? http://imgur.com/a/zM1MX Homework Equations W=Fd, Ek=1/2mv^2 The Attempt at a Solution Since the block was at...

A particle of mass 3kg moving at 15ms^−1 collides with one of mass 2 kg moving at 5ms^−1 in the same direction. Calculate the velocities after the collision i. the collision is elastic. ii. Suppose that in the collision of part (i), the final velocities are not parallel to the initial...

I am pretty confused about how to write Navier-Stokes Equation into conservation form, it seems that from my notes, first, the density term with the pressure gradient dropped out. and second, du^2/dx seems to be equal to udu/dx. Why is it so? I attached my notes here for your reference.

Homework Statement THIS PROBLEM CONSISTS OF NOTHING MORE THAN WHAT IS BEING STATED (NO VALUES, NO EQUATIONS, NOTHING) THIS IS A WORD PROBLEM WHERE NO CALCULATIONS ARE TO BE MADE: A mass hangs from a vertical spring and is initially at rest. A person then pulls down on the mass, stretching the...

Homework Statement A firework is shot from the ground at a speed of 50 m/s and an angle of 45 degrees. At its highest point it blows up into two pieces due to internal forces. One piece (.25 mass) falls straight down to the ground below the explosion, where does the second piece land? Homework...

Homework Statement So during collisions between 2 point masses, I know that momentum is always conserved, but energy may or may not be conserved. Now, in this case, where we have a block colliding with a pivoted rod, I know that angular momentum is always conserved, but neither energy or...

Homework Statement Will momentum not be conserved in the case of a free fall because gravity is considered an external force? Is this because the system is not isolated? If this is the case, I understand the concept now, but could someone give me another example of an external force that will...

Homework Statement A 259 g textbook slides up a 22.1° incline that is 2.55 m long. Using conservation of energy and assuming the incline is frictionless, what minimum initial speed is needed to accomplish this? mass = 0.259 kg Θ = 22.1° length of incline = 2.55 m Homework Equations KE =...

Homework Statement Ball mass = 0.0027 kg PE (0.5 meters) = 0.01323 J height of ball after three trials = 0.19 meters KE before bounce = 0.01323 J PE at new max height = 0.00503 Total energy = KE + PE Ke after bounce = ? Homework Equations mgh The Attempt at a Solution I did a lab where I...

Homework Statement Homework Equations Conservation of liner and angular momentum H1=H2 r x M1V1= r x M2V2 G1=G2 M1V1=M2V2 The Attempt at a Solution I've gotten an equation for the velocity of the block and clay after the impact, and I also know that when the block reaches the highest point...

Homework Statement Block A (of mass MA) rests on a frictionless horizontal table. It is connected via a light string to block B (of mass MB) hanging over the edge of the table. The pulley itself, a solid disc, has non-negligible mass MC. The light string does not slip over the pulley. What is...

Homework Statement Two identical particles of mass m travel towards each other at speed v; they combine and form a single new particle. By employing conservation of momentum and conservation of energy, what is the mass of this new particle in Homework Equations Relativistic momentum and total...

ηϖ1. Homework Statement Homework Equations I=½MR2 PE=mgh The Attempt at a Solution The first thing that jumped out at me was "uniform cylinder" so I went ahead and calculated the moment of inertia for the cylinder and got I=½(4.4)(.4)2 = .352 and held onto that. Then, I calculated the...