What is Conservation: Definition and 999 Discussions

Conservation biology is the study of the conservation of nature and of Earth's biodiversity with the aim of protecting species, their habitats, and ecosystems from excessive rates of extinction and the erosion of biotic interactions. It is an interdisciplinary subject drawing on natural and social sciences, and the practice of natural resource management.The conservation ethic is based on the findings of conservation biology.

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  1. facenian

    Conceptual problem with angular momentum conservation

    Let ##L(\vec{r},\dot{\vec{r}})## be the lagrangian function, usually to get angular momentum conservation one impose ##\delta L=0## and form there we get ##\sum \vec{r}\wedge m\vec{v}=const##. There is however a conceptual problem with this procedure related to the fact that invariance under...
  2. arpon

    Applying law of momentum conservation

    Homework Statement Suppose, a rod of negligible mass has two balls(A & B) at its two ends. Both the balls have same mass m. The rod is rotating around its center C with a uniform angular velocity ##\omega##. Another ball D (mass M) has a velocity v. At some time, A and D collide with each...
  3. terryds

    Conservation of momentum for accelerating object

    I always see that a ball moving in a constant speed collide with another ball is common conservation of momentum problems. Obviously, I know that the momentum is mass*velocity But, what if the ball accelerates and collides with another ball ? I think I can't use mass*velocity for the momentum...
  4. H

    Conservation of energy with springs

    Homework Statement A spring of negligible mass has force constant k = 1800N/m . You place the spring vertically with one end on the floor. You then drop a book of mass 1.20kg onto it from a height of 0.500m above the top of the spring. Find the maximum distance the spring will be compressed...
  5. Neil Graham

    Conservation of Energy in Space

    Imagine bringing a toaster and a slice of bread into space. After doing so, we were to toast the slice, measure the temperature after toasted, then chuck the piece of toast out into space quickly before too much heat transfers. After a week goes by, we find the piece of toast and bring it back...
  6. terryds

    Conservation of Energy in circular motion

    Homework Statement http://www.sumoware.com/images/temp/xzmomoeqpspoqxcq.png A block with mass m is static at first at the height of 2R (see picture above) and then slides without friction. a) Determine where the block leaves the track b) Determine the maximum height which the block reaches...
  7. Spinnor

    Vac fluct e+/e- field correlated because charge conservation

    Are fluctuations of the electron/positron field correlated in space and time because of charge conservation? We can't just have some positive charge just pop into existence, even if only for a moment? Thanks for any help!
  8. S

    Conservation of relavistic energy

    Problem statement, equations, and work done: A particle called a Kaon is moving at 0.8c through a detector when it decays into two pions. Kaon particle: mass = 493.7 MeV/c^2 Pion+: mass = 139.6 MeV/c^2 Pion0: mass = 135.0 MeV/c^2 1) Apply conservation of momentum/energy to determine the...
  9. Clear Mind

    Is Charge Conserved in Electromagnetic Interactions Between Particles?

    Suppose you have two charged particles that interact by e.m. potential ##V(\vec{r_1},\vec{r_2})##, the total charge is conserved. Since there's a conserved quantity, it must exist a transformation for which the hamiltonian is invariant (Noether theorem). Let's be the operator ##U##...
  10. D

    Tire stuck in mud - energy conservation

    Rg. Without air resistance, show the maximum height snow can reach is h_max=R+v^2/(2g)+gR^2/(2v^2) Solve using conservation of energy How do I start this problem? I assume all the initial kinetic energy ((mv^2)/2) from the spinning of the tire is translated to the gravitational potential energy...
  11. S

    2D conservation of Energy and Momentum with *Three* unknowns

    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...
  12. S

    Conservation of Momentum - Inelastic Collisions

    Hello, I recently posted a few conceptual questions regarding conservation of momentum. I'm processing the information more easily now, but I've hit yet another bump in the road. I've learned that in an inelastic collision in which "velocity is the same before and after the collision" the...
  13. Amaterasu21

    Momentum conservation, the double slit and Heisenberg

    One thing that's been troubling me lately is the idea that a quantum experiment can start with the same initial conditions, but the outcome is probabilistic, not deterministic, and how this fits in with the conservation of momentum. I was thinking about the classic double-slit experiment, in...
  14. Y

    Fluids: Conservation of Momentum

    Ok, so for the derivation of the Navier Stokes, the conservation of momentum through a control volume (CV) is Time rate of Momentum Change in CV = Time rate of Momentum Change into CV - Time rate of Momentum Change Out of CV + Sum of External Forces Why is Sum of External forces in there? I...
  15. Y

    Conservation of Energy Confusion

    Question: A person wants to jump in the air. To do so, he has to crouch a distance C. He then has a push-off phase, where the he accelerates upwards by a distance C. At the end of push-off, he then achieves takeoff (airborne). The end of his takeoff distance is H, and H is the difference between...
  16. S

    Conservation of Angular Momentum vs. Conservation of Energy

    Homework Statement Hi all! I have a very simple problem, which seems to get two different answers depending on whether you use conservation of angular momentum, or energy. Both quantities seem to be conserved: Initially we have a disk of radius a spinning about its center of mass at known...
  17. M

    Conservation of momentum when two objects collide

    when two objects collide some kinetic energy can be lost to heat, so some of the kinetic energy of the two colliding objects transfers to the individual particles of these objects. Does the same thing happen for momentum?
  18. Fosheimdet

    Compton scattering; conservation of momentum violated?

    While reading the derivation of the formula \lambda' - \lambda = \frac{h}{ m_ec}(1-cos(\theta)) on Wikipedia, they point out that the momentum gained by the electron is larger than the momentum lost by the photon: $$ p_e=\frac{\sqrt{h^2(\nu-\nu')^2 +2h(\nu-\nu')m_ec^2}}{c} >...
  19. A

    Conservation of momentum of two boats

    Say you had two boats (a and b) moving past each other without colliding and a man moved from boat a to boat b. Is it correct that boat b would decelerate and boat a would accelerate due to the conservation of momentum
  20. K

    Conservation of momentum and conservation of mechanical energy

    What are the conditions necessary for applying the conservation of mechanical energy or the conservation of momentum? Can we apply these anywhere or do we require specific conditions which have to be fulfilled for applying them?
  21. H

    Angular momentum conservation

    Homework Statement A person stands on a platform, initially at rest, that can rotate freely without friction. The moment of inertia of the person plus the platform is IP. The person holds a spinning bicycle wheel with its axis horizontal. The wheel has a moment of inertia Iw and angular...
  22. S

    Conservation of energy and time-varying forces

    Are there elementary mechanics problems that illustrate the phenomena of time varying force fields and energies associated with such fields? Problems in elementary mechanics are often solved by using the principle of conservation of energy even though "the system" (of masses, pulleys, inclined...
  23. binbagsss

    GR: Quick Q, conservation energy, stuck on algebra

    I'm stuck on deriving the follow. Context: FRW Metric, dust dominated universe, use of conservation of energy-momentum tensor. I'll now state all the equations I can see are relevant. (But just in case the source is http://arxiv.org/pdf/gr-qc/9712019.pdf and it's eq 8.43). ## \frac{d}{dt}(\rho...
  24. D

    Max Extension of Spring: Conservation of Energy w/ Masses M & m

    Hi. I'd like to find the maximal extension of a spring. The spring has a spring constant k. There's a mass m connected on the spring. From a height h above the initial location of mass m another mass M falls. When the two masses make contact they move as one. I found two methods to calculate...
  25. mukul

    Adiabatic effusion and violation of energy conservation

    when the gas effuse out of an insulated container, its velocity is given by \sqrt{\frac{2\gamma RT}{(\gamma-1)M}} (irodov's problem 2.42) This leads to the result that every mole of leaking gas has an energy of \frac{\gamma RT}{(\gamma-1)} whereas we know the energy contained in 1 mole of gas...
  26. binbagsss

    Decays possible? Parity conservation, bosons, fermions

    1. Homework Statement The question is to determine which decays are possible for: i) ##P^0 ->\prod^+ \prod^-## ii)##P^0 ->\prod^0 \prod^0## Homework Equations where ##J^p = 0^-, 1^- ## respectively for ##\prod^+, \prod^- , \prod^0## and ##P^0## respectively. The Attempt at a Solution For...
  27. S

    Conservation of linear Momentum Theory

    Homework Statement You are standing on your skateboard, which is at rest. Your friend throws a heavy ball at you. What should you do to minimize your velocity? A. Catch the ball B. Hit the ball back with the same velocity C. Neither, they both have the same effect. I would say (A). Because...
  28. A

    Deriviation for law of conservation of energy

    I'm a bit confused about how the work-energy theorem for a single particle can be extended into the general law of conservation of energy for the macroscopic system, particularly the point where we divide the kinetic energy of the system into macroscopic kinetic energy and internal kinetic...
  29. J

    Projectile Motion Using Conservation of Energy

    Homework Statement Exam review question concerning 2 dimensional motion, the professor did not hand out an answer key and I am just looking for an answer check. A car launches at an angle of 30 degrees above the horizontal, off a cliff (50m), moving at an initial speed of 10m/s. Find the...
  30. R

    Thermodynamics and conservation of energy

    I have a question about conservation of energy in my system A heat pump allows you to move a quantity of heat with a smaller energy input. It is most efficient for small temperature differences. A heat engine allows you to convert a temperature difference into mechanical work. It is most...
  31. S

    Conservation of Angular Momentum Help

    Homework Statement Below is the question: I only have an issue with the last step of the problem. Why wouldn't you factor in the translational AND rotational energy of the ball and then solve for maximum height?
  32. G

    Conservation of Energy with non-allowed states

    (This though came up while learning about band structure, so that is how I am going to explain it, but I think it applies equally well to a square well, for example). Say you have an electron at the Fermi level of an insulator. Then, you apply an electric field. No current flows, because all...
  33. avito009

    Law of conservation of Angular Momentum

    Keplers second law: An imaginary line joining a planet and the sun sweeps out an equal area of space in equal amounts of time. So this shows that the Earth would move faster if it was near the sun. Why? I have read that an abject will move faster if the mass has become smaller. If mass has...
  34. J

    Momentum, Force and Conservation

    Homework Statement Three smooth stones, A, B and C are initially at rest, in contact with each other on the smooth surface of a frozen lake (Figure 1). The masses of the stones are, to 3 significant figures, mA = 8.00 × 10^2 g, mB = 6.00 × 10^2 g and mC =2.50 × 10^2 g and the coefficient of...
  35. S

    Conservation of energy and momentum

    this would be considered as an inelastic collision where (m1v1) + (m2v2) = (m1+m2)vf also the conservation of energy being (∆K +∆U)=0 i tried using the conservation of energy to find v2 as the variable we are looking for is Vf, the speed the bullet leaves the block, and v2 (velocity of the...
  36. P

    Conservation of Linear momentum - confusing question?

    Homework Statement Homework Equations Momentum = mass x velocity The Attempt at a Solution Answer is A. when mass decreases, speed should increase for momentum to be constant. and when mass increases, velocity decreases. i could understand the graph up the before t2 with this. but at t2...
  37. D

    Conservation of Energy falling rod

    Homework Statement A uniform ladder having mass 14kg and length 3m is released from rest when it is in the vertical position. If it is allowed to fall freely, determine the angle Theta at which the bottom end A starts to lift off the ground. For calculation assume the ladder is a slender rod...
  38. L

    D’Alembert’s principle and conservation of energy principles

    Homework Statement A load of 10 kg is pulled up a lubricated slideway, set at an angle of 30° to the horizontal, such that the load is accelerated from rest to a velocity of 1 m/s whilst traveling up the plane through a distance of 1 m. The frictional resistance to this motion is 10 N and g =...
  39. gcombina

    Conservation of Momentum - BOMB EXPLOSION question

    Homework Statement QUESTION 1 :A stationary bomb explodes in space breaking into a number of small fragments. At the location of the explosion, the net force do to gravity is 0 Newtons. Which one of the following statements concerning the event is true? a) Kinetic energy is conserved in the...
  40. ximsooriginalx

    Conservation of Momentum of a ball

    Homework Statement A ball is thrown against a fixed wall where it bounces elastically. The mass of the ball is M and the velocity just before it hits the wall is U. Ignore the force of gravity in this question. a) Does the Principle of Conservation of Momentum apply to this situation? b) Obtain...
  41. C

    Conservation of Energy of a System

    Homework Statement :[/B] There is a system, beginning from rest, with two masses, m1 and m2. M1 is on a table and attached to a rope that goes over a pulley (that is NOT massless)and attaches to hanging mass m1. Between m2 and the table there is a friction(kinetic) of 0.1 M1=10kg M2=30kg Mass of...
  42. Q

    Conservation of momentum and mass of a ball

    Homework Statement A 0.160 kg ball makes an elastic head-on collision with a second ball initially at rest. The second ball moves off with half the original speed of the first ball. a) what is the mass of the ball b) what fraction of the original kinetic energy gets transferred to the second...
  43. A

    Conservation of energy and quantum weirdness

    Where, when, and why did the notion of conservation of energy become a law? I know that we are able to "invent" new means of "fixing" any apparent violations of this and further I understand that the new inventions of other energy forces have led us to new ways of seeing the world but I still...
  44. Q

    Conservation of Momentum law problem

    Homework Statement m1= 3kg m2= 6kg v1 = 5m/s v2= 2m/s d = 3m DIAGRAM : http://gyazo.com/17b3126726b109256a35f65b86708bb0 Homework Equations Conservation of momentum: m1+v1 = m1v1'+m2v2' Conservation of elastic: m1v1^2+m2v2^2 = m1v1'^2+m2v2'^2 The Attempt at a Solution Now my attempt...
  45. E

    How Fast Must a Car Go to Clear a 12m Loop and What Are the Max G-Forces?

    1. So the loop is known to be 12m in diameter (6m radius). Assume the car weighs 1250kg - how fast must the car go to clear the loop, and what will be its max G-forces endured? This was the question, which I have broken into 3 sections: a) Velocity at top of loop (done) b) Velocity at start of...
  46. S

    Conservation of Momentum/KE

    Homework Statement Two pieces of clay collide and stick together. During the collision, which of these statements are true? (a) Only the momentum of the clay is conserved, (b) only the mechanical energy of the clay is conserved, (c) both the momentum and the mechanical energy of the clay are...
  47. J

    Can we use conservation of energy law to find final velocity

    Homework Statement It's a simple problem, you kick a ball with an initial velocity of 5.4 m/s, the angle is 30 degrees. So the question is when does it land on the ground? So I thought that I could find final velocity so that I can use V = V(initial) + acceleration * time. My question is, can...
  48. binbagsss

    Conservation of four-momentum concepts, frames

    I've read that they must be calculated in the same frame , and so to calculate them in the easiest frame.. * So for a collision when I compute the momentum before and after I should do this in the easiest frame. Considering a specific collision where we are computing the minimum energy to...
  49. Q

    I have a question about a problem of conservation of momentu

    Momentum in rigid bodies; In this problem when I draw all the forces acting on the disc A, would the reactions: Ax, Ay; W, Friction, normal force; I do not understand is how to check that Ay = W, that's what I understand from the solution. Anyone have any tips on how to treat reactions in such...
  50. J

    Explaining depths reached by swimmer by conservation of energy/momentum

    Homework Statement If you dive into water, you reach greater depths than if you do a belly flop. Explain this difference in depth using the concept of conservation of energy. Explain this difference in depth using what you have learned in this chapter**. ** It is referring to the chapter of...
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