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.

View More On Wikipedia.org
Recent contents Top users
  1. M

    I Conservation of energy in quantum measurement

    A measurement of an observable that does not commute with energy will generally cause a change in the expectation value of the energy. Is there a clear formalism to describe how energy is conserved overall?
  2. RoboNerd

    Implementing angular momentum approach in problem

    Homework Statement An object is in uniform circular horizontal motion at the end of a chord of length L. Its tangential speed is v. The chord is pulled into length 0.5L in such a way that the tension in the chord remains constant. As a result, the tangential speed: a) remains constant b)...
  3. RoboNerd

    Ratio of angular speed with conservation of energy

    Homework Statement A ball rolls down an incline plane without slipping. What is the ratio of its angular velocity at h/3 to its angular velocity at 2h/3? 1) 1:2 2) 1:sqrt(2) 3) 1:1 4) sqrt(2):1 5) 2:1 Homework Equations Conservation of energy with provisions for rotational and...
  4. E

    Conservation of momentum and SHM

    Homework Statement Two point masses m1 and m2 are coupled by a spring of spring constant k and uncompressed length L0. The spring is fully compressed and a thread ties the masses together with negligible separation between them. The tied assembly is moving in the +x direction with uniform speed...
  5. Xico Sim

    I Isospin conservation - an application

    Hi guys! I'm trying to understand how to use the fact that the total isospin is conserved in all strong processes in the particular case (vide Griffiths, pages 118 and 119): $$ p+p \rightarrow d+\pi^+ $$ Griffiths first argues that the deuteron d has isospin I=0, because of experimental...
  6. Michele Zappano

    Fractal Symmetry & Noether's Theorem: Chaos & Conservation

    I was reading a Steven Strogatz book and he said that the self similarity of fractals is a symmetry. Has any conservation law been linked to this type of symmetry using Noether's Theorem?
  7. R

    Conservation of linear & angular momentum head on collision

    Homework Statement Two cars collide head on but offset from each others center of gravity. After the impact the two cars are locked together as one body. Due to the location of the collision point, the impact causes the two locked cars to spin clockwise. Car A- traveling west going 10 mph...
  8. B

    Calculating Combined Mass of Archer & Bow w/ Conservation of Momentum

    Homework Statement After shooting a 28g arrow with an initial velocity of 92m/s[forward], an archer standing on a frictionless surface travels in the opposite direction at a speed of 0.039m/s. Calculate the combined mass of the archer and the bow. Given: **Subscript of 1 indicates values for...
  9. E

    I Spacetime expansion and conservation of energy

    I came across this issue a while ago, when spacetime expands, then energy doesn' seem to be conserved? But does not that violate the law of conservation of energy? I don't get it, how can spacetime expansion happen without energy issues? Thanks in advance
  10. R

    I Energy conservation and information conservation

    How is information conserved when one form of energy is converted to other? Like how a black hole's gravitational energy is used to create photon pairs near the event horizon, what happens to the information in the gravitational wavepackets (gravitons?) and how is it not lost?
  11. RoboNerd

    Question on energy conservation with centripetal acceleratio

    Homework Statement The right answer is E, and I have no idea how to solve this problem. Please advise on how to proceed. Thanks in advance. Homework Equations conservation of mechanical energy?? The Attempt at a Solution Many attempts were done, but I am lacking on theory with this. How...
  12. A

    How is conservation of momentum present in an airbag?

    How is conservation of momentum present in an airbag?
  13. RoboNerd

    Question about conservation of linear momentum

    Homework Statement [pardon my crude drawing] Say I have a ball that hits the a rod at rest pivoted around hinge A. The ball in the diagram is the solid black, and the rod is the thin line in the diagram and is rotating around the square-shaped hinge at the bottom. I am not an artist but...
  14. MullaTheMech

    Conservation of charge vs force

    So I was posting questions in someones homework help and I thought I'd create my own thread instead. https://www.physicsforums.com/index.php?threads/868492/ Now in coulombs equation you multiply the coulombs (Q1×Q2) Ujjwal (OP in other thread) was using 2 balls charged at 2 and 3 coulombs in...
  15. B

    B 2 events in a planck time not violate conservation of energy

    This thread is about a topic that unexpectedly came up in my thread titled "Contradiction between Cosmos and what someone here told me?". I will subsequently call that thread "Contradiction" for brevity. I am not sure if this thread belongs on the Quantum Physics forum or the chemistry forum...
  16. S

    Angular momentum conservation and constant velocity as expla

    I'm confused about situations involving rotating frames in which the angular momentum is conserved and the initial velocity does not change. I'll make an example. Take a rotating carousel (constant angular velocity) with no friction on it and a ball. At the initial time instant the ball has the...
  17. V

    Is this a simple energy conservation problem?

    Homework Statement Homework EquationsThe Attempt at a Solution The answer to this problem can be obtained by equating ##\frac{1}{2}mv^2 = ΔU## . But I am not sure why this is to be done . In fact I think this is not quite right . 1) The Kinetic energy ##\frac{1}{2}mv^2## is the energy due...
  18. i_hate_math

    Conservation of Angular momentum problem

    Homework Statement In the figure, a small 0.235 kg block slides down a frictionless surface through height h = 0.471 m and then sticks to a uniform vertical rod of mass M = 0.470 kg and length d = 2.36 m. The rod pivots about point Othrough angle θ before momentarily stopping. Find θ. Homework...
  19. O

    A Conservation of Information: Neutron Formation and Decay

    Has anyone analyzed the process of Neutron formation and decay from the perspective of "information conservation"? Does anyone have any thoughts on what the results of such an analysis would be? What is the status of the observed evidence of reality in respect of whether one should conclude...
  20. S

    Smooth rolling motion - conservation of energy?

    This isn't about a specific physics problem, but rather a question: Given I have a ball or cylinder rolling smoothly along some path, is it generally true that mechanical energy is conserved? I.e. if ##E_mech = K+U = K_{trans} + K_{rot} + U##, then ##\Delta E_mech = 0##? I have been able to...
  21. S

    Coriolis force and conservation of angular momentum

    I'm trying to understand the relations between the existence of Coriolis force and the conservation of angular momentum. I found this explanation on Morin. I do not understand the two highlighted parts. In particular it seems that Coriolis force is there to change the angular momentum of the...
  22. F

    I Conservation of matter energy momentum tensor beyond GR

    Hello, Is the covariant conservation of the matter energy momentum tensor Tμν ; μ = 0 also valid in a theory of gravity having an action for the gravitational field different from the Einstein Hilbert action ? I'm asking because in GR the einstein field equations require Tμν= Gμν where Gμν;μ=0...
  23. RoboNerd

    Linear Momentum of system of two blocks

    1. Homework Statement The problem is shown in the photo above. I would like to discuss part B. Homework Equations conservation of linear momentum The Attempt at a Solutionthe solutions say that we should have the following approach: Mb*vb = [Mb + Ms] * vFinal. Plug in the numbers and get vF...
  24. D

    Applying Conservation of Momentum to Car Collision

    Homework Statement Homework Equations conservation of momentum 3. The Attempt at a Solution initially car_1 has not y momentum so \begin{equation} m_1v_1x=(m_1+m_2)v cos(θ) \end{equation} and car_2 has no x momentum \begin{equation} m_2v_2y=(m_1+m_2)v sin(θ) \end{equation} using...
  25. S

    Forces that cause acceleration due to conservation laws

    I find difficulties in identify the forces acting behind the acceleration of objects that are considered consequence of conservation principles (for istance of KE and angular momentum). I'll make an example to explain. The same string-mass system is linked to a rod. In case (a) a force pull the...
  26. S

    Acceleration only due to conservation of angular momentum

    I don't understand why the conservation of angular momentum can imply an acceleration, in absence of a force. Consider for istance planetary motion. The angular momentum \vec{L} of the planets is conserved and that means \mid \vec{L} \mid=mr^2 \dot{\theta}=mrv_{\theta} is conserved too...
  27. Aarron Anderson

    Angular Momentum and Conservation of Angular Motion

    Homework Statement How much torque is needed to change the speed of spinning rate of a 3.50 kg sphere with a radius of 7.50 m from 900. rpm to 200. rpm in 3.0 s? [-1924  -1.92 x 103 Nm] Homework Equations t = I * α I = (2/5)mr^2 t = F * r The Attempt at a Solution just can't get a crack at...
  28. S

    Conservation of Energy: Finding the Speed of a Falling Ball

    Homework Statement [/B] The coefficient of friction between the block of mass m1 = 3.00kg and the surface in Figure P7.22 is μk = 0.400. The system starts from rest. What is the speed of the ball of mass m2 = 5.00 kg when it has fallen a distance of h = 1.50m? Homework Equations This is in...
  29. U

    A basic conservation of energy question

    The question asks: Uranium nuclei are unstable and decay by emitting a helium nucleus, which contains two protons and two neutrons. Suppose the original nucleus has 92 protons and 146 neutrons before it emits the helium nucleus, and that the helium nucleus has an knknown speed as it departs from...
  30. Bigger than smaller

    Conservation of Charge in Series Capacitors.

    Hi. I have a question about conservation of charge when two differently charged capacitors are connected in series. I know this is like a homework problem of introductory level of physics, but since this is not my homework, I decided to post it here. So, here is the story. There are two...
  31. S

    Relative motion and conservation of momentum

    Homework Statement A 52kg man is on a ladder hanging from a balloon that has a total mass of 450kg (including the basket passenger). The balloon is initially stationary relative to the ground. If the man on the ladder begins to climb at 1.2m/s relative to the ladder, (a) in what direction does...
  32. D

    Violation of conservation of momentum?

    According to amperes force law two parallel wires with current flowing in the same direction will experience a magnetic force attracting them together. consider two 1cm long wires parallel to each other, separated by a distance of 1cm. Pass a current through both of the wires for the time it...
  33. D

    Recoil on mirrors and conservation of momentum

    I wanted to know whether or not a perfect mirror would experience recoil when light reflects off it, and I also wanted to know whether or not light can cause a recoil during total internal reflection. I suspect that the recoil is negligible (Even with a normal mirror) and that you could easily...
  34. S

    Double ball drop and conservation of momentum

    Homework Statement The classic double ball drop question: a ball of mass m is placed directly above another ball of mass M, and assume that m is not negligible. Both balls are dropped simultaneously. Find the mass m such that, upon the second collision (m with M), M has a final velocity of...
  35. G

    Bernoulli vs Energy Conservation?

    In the example, is it possible to have same velocities at the two ends of the tube? How would you construct energy conversation equation?
  36. RoboNerd

    Quick Question on Kepler & angular momentum conservation

    Homework Statement Homework Equations I guess kepler's law but most importantly conservation of angular momentum are key here. The Attempt at a Solution [/B] I put down E as the answer, but the solutions have D as the correct answer. Why is this the case? Thanks in advance for the help!
  37. J

    Collision conservation of energy

    Homework Statement Jack (mass 59.0 kg ) is sliding due east with speed 8.00 m/s on the surface of a frozen pond. He collides with Jill (mass 46.0 kg ), who is initially at rest. After the collision, Jack is traveling at 5.00 m/s in a direction 34.0∘ north of east. Ignore friction. Homework...
  38. 2

    Conservation of angular momentum of a stick

    Homework Statement A uniform stick 1.00 m long with a total mass of 270 g is pivoted at its center and is initially stationary. A 30 g piece of clay is thrown at the stick midway between the midpoint of the stick (pivot) and one end. The clay piece is going at 50 m/s and sticks to the stick...
  39. J

    Why is the elastic potential energy when extension is (a+l/20) included?

    1. Homework Statement I'm working on the second part of this question and I want to find the initial speed before P strikes the barrier. So I used principle of conservation of energy, K.E at Equilibrium position + elastic p.e. at Equilibrium positon = K.E just before it strikes the barrier +...
  40. F

    Conceptual question regarding the conservation of energy

    Hi PF, I've got a very trivial conceptual question regarding the conservation of energy with respect to thermodynamics and heat transfer that I can't seem to figure out. Suppose I have an electric heating element with a 240 volt, 30 amp supply, in contact with a solid volume of an arbitrary...
  41. JulienB

    Conservation of angular momentum

    Hi everybody! I'm preparing myself for upcoming exams, and I struggle a little with conservation of angular momentum. Can anybody help me understand how to solve such problems? 1. Homework Statement (for a better comprehension, see the attached image) We have a wooden cylinder of mass mZ =...
  42. J

    Conservation of energy - elastic potential energy and k.e.

    1. Homework Statement For part (iii) , I used the principle of conservation of energy, K.E of the 2 kg particle after collision + E.P.E = K.E of the 2 kg particle at the furthest distance away from A + E.PE, But the solution for this question did not include the E.P.E of the string...
  43. Ameer Bux

    Violation of conservation of energy?

    By squeezing a spring until it coils up, it then has more potential energy. So it will then have more mass, because mass is energy. So doesn't that violate the law of conservation of energy. The spring has more energy and mass after its squeezed than when it wasn't squeezed?
  44. M

    Atomic Conservation in Ionized Hydrogen Gas

    Dear all, So I have a question concerning atomic conservation in an ionized hydrogen gas. So imagine we have ## H_2 ## initially. Later the gas is taken to an appreciable temperature such that at equilibrium the following species are present, ## e^-, \ H, \ H^+, \ H_2, \ H^-, \ \text{and} \...
  45. F

    Conservation of Mechanical Energy Requirement

    Hello Forum, Conservation of mechanical energy ME= KE+PE happens when the net work done by the non conservative forces is zero. Conservation of total momentum, instead, happens when the external net force is zero (or close to zero). In the case of mechanical energy, the non-conservative forces...
  46. N

    B Neutrino change of flavour and conservation of energy

    Hello, I have a simple question. Has the discovery that some neutrinos change their flavor posed any issues with conservation of energy?! How has this been solved?! Thank you.
  47. A

    Confusion regarding application of Conservation of Momentum

    Homework Statement Actually, my confusion originated from solving two different problems... 1) A point object of mass 'm' moving horizontally hits the lower end of the uniform thin rod of length 'l' and mass 'm' and sticks to it. The rod is resting on a horizontal, frictionless surface and...
  48. R

    Potential energy and conservation of energy

    When a particle (or any objects) accelerates when acted upon by fundamental forces, what is happening to the amount of energy in that particle? A large example would be an asteroid in space caught by Earth's gravity and accelerates toward Earth as a result. The fundamental forces here can be...
  49. J

    Collision Conservation of Energy

    Homework Statement a 5.0 x 10^5kg railroad car moving at 8.0m/s. collides with a stationary railroad car of equal mass. after the collision the two cars lock together and slide forward. What is the final velocity of the wrecked cars? using conservation of energy M1 = 5.0 x 10^5 kg M2 = 5.0 x...
  50. P

    I Understanding Hamiltonian Conservation Laws

    I'm a little confused about the hamiltonian. Once you have the hamiltonian how can you find conserved quantities. I understand that if it has no explicit dependence on time then the hamiltonian itself is conserved, but how would you get specific conservation laws from this? Many thanks
Back
Top