Conservation Definition and 999 Threads

I did a quick search through the forums and didn't find the answers I was looking for, so I thought I'd ask. Does charge conservation still apply for collisions between elementary particles? I'm taking a second year foundations of physics course, and we were given a fairly simple looking...

Homework Statement A 250 gram rock is thrown with a speed of 30.0 m/s. It has a speed of 22.5 m/s just before it strikes the ground. Determine the work done by air resistance. There is also a diagram which yields more information. The rocks path is horizontal and it strikes the corner of a...

In an explanation of a textbook's diagram it says : "Conservation of charge requires that whatever charge flows into the resistor at point A, an equal amount of charge emerges at point B. Charge or current does not get “used up” by a resistor. So the current is the same at A and B. " I can...

Homework Statement A frog sits on the end of a long board of length L=5m . The board rests on a frictionless horizontal table. The frog wants to jump to the opposite end of the board . What is the minimum take-off speed (in s.i. Units) i.e.,relative to ground 'v' that allows the frog to do the...

I know there has been a lot of threads on the forum about this topic, but my question is slightly different from the others. I have recently read this article by Sean Carroll (http://www.preposterousuniverse.com/blog/2010/02/22/energy-is-not-conserved/); now, I'm completely aware (& convinced)...

Homework Statement So I'm trying to prove to myself that energy is conserved in the case of magnetism. Here is the set up that I'm using to get that understanding (attached image). Just to be clear the arrows represent the current lines and I am calculating a gain in PE because if I release...

Homework Statement [/B] Three masses are positioned on a frictionless surface, as shown. Initially, mass m1 (1.0 kg) moves with a velocity of 2.0 m/s to the right, mass m2 (2.0 kg) is at rest, and mass m3 (3.0 kg) moves to the left with a velocity of 0.50 m/s. First, mass m1 collides...

Hello, I have found an issue in a simple classical electrodynamics problem that I have not been able to explain, so I’m writing this post hopping to find some answer to it. The problem is this: we have two charged particles with the same charge but different sign, one is massive and I will...

Everybody experiments fatigue holding a weight, and almost everybody knows that points of applications of the involved forces don't move. We also know that we cannot use the standard equation of the conservation of energy ( ΔK + ΔU = Wext ) because the system (Body+weight) is composed by...

Homework Statement A frog of mass m jumps from the edge of a plank of mass M of length L to the other edge. The plank is on water and is free to move, assume no friction whatsoever. What is the minimum value of the speed of the frog ? Homework Equations Conservation of momentum and energy Some...

Homework Statement A 4.60-kg ball, moving to the right at a velocity of +2.31 m/s on a frictionless table, collides head-on with a stationary 9.80-kg ball. Find the final velocities of (a) the 4.60-kg ball and of (b) the 9.80-kg ball if the collision is elastic. (c) Find the magnitude and...

If quantum foam particles can exist long enough to interact with other close particles before returning to the vacuum, doesn't this introduce kinetic energy to a system that previously didn't have it before? Does this perhaps imply that a system (such as the universe) cannot actually be isolated...

So, this is something I've never understood in detail. If an excited system decays and emits a photon, the lifetime of the decay will broaden the spectrum of the photon right? Basically just a Fourier transform of the "shape" of the emission in time to get the frequency components of the...

Suppose we take the three Newton’s Laws as axioms. Existence of inertial reference frames F = ma F(A on B) = -F(B on A) Also suppose also we are considering purely classical mechanical processes on point particles (no heat transfer, etc.). It is clear to me that the conservation of momentum...

Question: A streetcar is freely coasting (no friction) around a large circular track. It is then switched to a small circular track. When coasting on the smaller circle its speed is: a) greater b) less c) unchanged Relevant Formulas: w = v/r KE = 1/2mv2 My teacher said the normal force from...

Homework Statement Homework Equations Conservation of Energy (Potential + Kinetic = Potential + Kinetic) The Attempt at a Solution At the start of the ramp, potential energy is mgh (gravitational potential) and kinetic is 0, since it's not moving. At the bottom of the loop, potential...

I have been busy with rotating objects and I have a question which I don't understand. http://dev.physicslab.org/Document.aspx?doctype=3&filename=RotaryMotion_AngularMomentum.xml (last question of the page, about the clay on the rod) What I don't understand is that the clay has a kinetic energy...

Three High energy Photons spontaneously convert into electron positron pairs, The electron on the left marked A is created and and destroyed within a short interval, sending an electric field burst towards electron B shortly after it's created, just enough so that Electrons B's electric field...

Homework Statement I am studying the topics listed above and have been having great difficulty getting my problems going. To explain, I am having difficulty seeing where the problem should go and attacking in that direction. I can draw out free-body diagrams but I can't see how to solve the...

Homework Statement A uniform 4.00kg square solid wooden gate 2.00m on each side hangs vertically from a frictionless pivot at its upper edge. A 1.30kg raven flying horizontally at 4.50m/s flies into this door at its center and bounces back at 2.50m/s in the opposite direction. What is the...

Homework Statement A skier starts at the top of a friction less hill. You have 4 different runs, they have different difficulties. So I am assuming they are at different inclines. 1) longest route, not so steep 2) medium length, little steeper 3) shorter more steep 4) straight path, and very...

The question is for which of the ##1P## meson states - ##1^{1}P_{1}, 1^{3}P_{0},1^{3}P_{1}, 1^{3}P_{2} ## ##D_{s}## states decaying to a ##1S## state is the decay: ##D_{s}**^{+} -> D_{s}^{+}\pi^{0} ## possible? Solution So the strong interaction conserves parity. Parity of meson is given by...

Homework Statement http://imgur.com/cEqXb24 Homework Equations Ki = Kf Li = Lf The Attempt at a Solution So I tried to solve this using conservation of energy as well as conservation of momentum, but only conservation of momentum gave the correct answer. Why can't conservation of energy be...

Homework Statement A girl of mass m1=60 kilograms springs from a trampoline with an initial upward velocity of vi=8.0meters per second. At height h=2.0 meters above the trampoline, the girl grabs a box of mass m2=15 kilograms. What is the speed of the girl after she grabs the box? Homework...

Homework Statement A train is traveling in the x direction at a speed of v. On the train, a passenger is playing darts and fires a dart in the y direction with a speed of Uy. The dart hits the target and stops abruptly. What is the difference in the mass of the dart as observed by a person on...

Homework Statement Hello everyone, I was hoping I could get someone to help me out please. I am having great difficulty with my thermodynamics course and I have an assignment due tomorrow. I need to reduce the conservation of energy formula so that it applies to Earth so I can work on my...

Homework Statement A ball with mass 2kg is traveling 2m/s. It impacts and sticks to a hanging, stationary 4kg pendulum. How high will the pendulum + ball go? Homework Equations KE = 1/2mv2 PEg = mgh mava = m(a+b)v(a+b) The Attempt at a Solution I tried to solve this question assuming...

Homework Statement Homework Equations Conservation of linear momentum for fluids The Attempt at a Solution This seemingly simple problem has me confused. First of all, I want to set up the sum of the foces as: -Min + Mout -Fx = 0 So first of all, not only does my Fx term have the wrong...

Homework Statement A 1Kg rocket is fired off. The engine provides a thrust of 18 Newtons for 20 meters. What is the maximum height achieved by the rocket? Assume no loss of mass and no friction. Gravity=9.8m/s^2 Homework Equations Work=Force x distance Force=Mass x acceleration(or gravity)...

Reading "Atmospheric Thermodynamics" I'm stumped almost as soon as I've started. I've probably bitten off more than I can chew and this also might even be more of a math question than a physics one but where I'm stuck is where they "simplify" from: mv . dv/dt = -mgv . ez (where ez is a unit...

I have a conservation of energy question I’ve asked about elsewhere but I didn’t get a fully satisfying answer. I hoping someone here can help. TIAhttp://wedgecircles.com/images/384_newmpe01.gifSay you have two magnetically aligned magnets close to one another but some distance apart. There...

Homework Statement A mass is attached to a spring (on a wall) of constant 100 N/m. The mass is 1 kg. The mass has an initial position of 3 m from the equilibrium position and is given an initial velocity of 5 m/s. Find the period and amplitude of oscillations. Homework Equations [/B] Period...

Homework Statement Four weightless rods of length ##l## each are connected by hinged joints and form a rhomb (Fig. 48). A hinge A is fixed, and a load is suspended to a hinge C. Hinges D and B are connected by a weightless spring of length ##1.5l## in the undeformed state. In equilibrium, the...

Homework Statement Under some circumstances, a star can collapse into an extremely dense object made mostly of neutrons and called a neutron star. The density of a neutron star is roughly 10^14 times as great as that of ordinary solid matter. Suppose we represent the star as a uniform, solid...

We all know that momentum is conserved in a system. But I am confused of one thing. Suppose we have a system containing a wall with very large mass and a ball and use a classical x-y coordinate axis. If I swing the ball at an angle of 45 degrees from the horizontal, upwards to the huge wall...

Consider a parallel plate capacitor in vacuum, we hold a test charge below one plate and release it at some point in time, we observe that the charge is accelerating towards the other plate, that is the charge is gaining kinetic energy. My question is how does the loss of energy from the...

Hey, Say we have an object released at rest, separated by a certain distance..blah, blah, blah. When we use conservation of energy here, the kinetic energy would have a initial velocity right? So, K1+U1=K2+U2 assuming the object eventually comes to a rest...so U1 = 0, K2 = 0, so we would have...

Homework Statement In the pictures Homework Equations Fnet = dp/dt The Attempt at a Solution I know in part b there is a net external force (gravity) that does positive work, fnet > 0, thus dp/dt is positive. Does the spring in part c increase or decrease the momentum of the system? I am...

Hey guys, I need help with conserving momentum at these vertices (this is Bhabha scattering): So in Diagram (a), the first vertext to the left. The incoming momenta are p_{1}+p_{2}. The outgoing momentum I'll call it p. So...shouldnt I have p_{1}+p_{2}=p? Furthermore, is the propagator...

Homework Statement Figure 10.30 shows two disks: an engine flywheel (A) and a clutch plate (B) attached to a transmission shaft. Their moments of inertia are and initially IA and IB, they are rotating with constant angular speeds ωA and ωB, respectively. We push the disks together with forces...

Homework Statement if the distance between the Earth and the sun were to be cut in half, what would be the number of days in the year? Homework EquationsThe Attempt at a Solution I can solve this question using simple centripetal force = gravitational force of attraction and then halving the...

Homework Statement A diesel engine weighs 8 times as much as a freight car. This diesel engine, moving on a horizontal track at 3 km/h, crashes into the freight car (which was moving at 2 km/h in the same direction). What is the velocity, in km/h, of the now linked together engine/car...

Homework Statement A roller coaster at an amusement park is at rest on top of a 30 m hill (point A). The car starts to roll down the hill and reaches point B which is 10 m above the ground, and then rolls up the track to point C, which is 20 m above the ground. (A) A student assumes no energy...

Homework Statement A 2.0 kg ball moving with a speed of 3.0 m/s hits, elastically, an identical stationary ball as shown. If the first ball moves away with angle 30° to the original path, determine a. the speed of the first ball after the collision. b. the speed and direction of the second...

I have a question about conservation of energy... So, I have a question about conservation of energy. I just want a detailed example of the path of the energy in some regular scenarios and the reach of it. For example... When playing pool, the cue ball is shot at a stationary 8 ball. The cue...

If I had a block that I pushed with a force F along a horizontal path and then removed the force before an incline, would the angle of the incline matter on how far above the ground the block would travel? I am assuming a frictionless surface.

Homework Statement A 59.8kg person holding two 0.902kg bricks stands on a 2.14kg skateboard. Initially, the skateboard and the person are at rest. Calculate the final speed of the person and the skateboard relative to the ground if the person throws the bricks one at a time. Assume that each...

Hi Guys, I was wondering; if electronic charge is conserved by Kirchoff's Current Law, then does this mean that the total number of electrons traversing any given circuit at any time is constant?

I don't know much about the topic but if I'm correct charge should always be conserved. What happens when two protons collide in the LHC? Don't they split into quarks and then decay, lowering the amount of positive charge in the system?

Homework Statement I'm stuck on this problem, and I don't really know how to approach it. Homework Equations Pretty much just p=mv And the conservation of linear momentum: total initial mv = total final mv The Attempt at a Solution I tried just plugging in the variables into the...