Conservation Definition and 999 Threads

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. TheQuestionGuy14

    Conservation of Energy and a billiard ball

    The conservation of energy states energy can never be created nor destroyed, and the amount of energy in a system is always constant. I'm just curious, say if a billiard ball just suddenly started moving without any other object making it do so, (kinetic energy was created), if it also suddenly...
  2. P

    Conservation of momentum - trampoline

    English isn't my main language, so I apologize in advance if something is unclear. We are leaving air resistance out of this problem! 1. Homework Statement We are going to describe the force F from the trampoline on the Joe as F = kx, k is a spring constant. This is a model. 1. Joe drops...
  3. S

    Percent error in conservation of momentum lab confusion

    Okay, so I did an elastic collision with Vernier carts and magnets. The results seem pretty good. Cart one started with -0.1205 kg*m/s ended with +0.1027 kg*m/s Cart two started with +0.1174 kg*m/s ended with -0.1118 kg*m/s So Total before = -0.0031 kg m/s and total after = -0.0091 kg m/s. If...
  4. S

    Exploring Conservation of Energy: Ball Dropped in Water

    My question: Consider an isolated system consisted of a ball, and a bucket of water. The ball is released from height, H above a bucket of water. The initial temperature of the water-bucket system and the ball are T1 and T2 respectively. What will be the final temperature of the water after the...
  5. Mason Smith

    Question involving the conservation of momentum

    Homework Statement Homework Equations The conservation of momentum states that if there are no external forces acting on a system, then momentum is conserved (i.e., the momentum before an event is equal to the momentum after an event). (Note: We assume that the internal forces follow Newton's...
  6. O

    Newton's law of conservation as it applies to the big bang

    I had a thought the other day and I am looking for someone to tell me why it does not work. In consideration of energy be neither created nor destroyed, to me this would say there is not enough energy to continue expanding the universe. I also make the conjecture the gravity never stop...
  7. B

    A Measurement and the Conservation of Momentum

    If you prepare a particle with a “relatively precise” momentum by the act of filtering or measuring its momentum. It’s state will collapse into a momentum eigenstate and the measured momentum will be the corresponding eigenvalue. The position state will now be nearly uniformly spread out and...
  8. brotherbobby

    Rotating physicist and momentum conservation

    We are aware of the well-known problem of a rotating physicist whose angular velocity ω increases as a consequence of angular momentun conservation (##I_1 \omega_1 = I_2 \omega_2, \Sigma \tau_e = 0##). I am assuming that the net external force (##\Sigma F_e##) is also zero along with the net...
  9. Hiero

    Conservation law associated with the symmetry of a helix

    In a problem in Landau’s mechanics (end of section 9) he asks for the quantity conserved in the field of “an infinite homogenous cylindrical helix.” The solution is that the Lagrangian is unchanged by a rotation of dΦ together with a translation of hdφ/(2π) (about and along the symmetry axis)...
  10. J

    The conservation of angular momentum

    This question is about the conservation of angular momentum: So far, I have understood the reason as to why an object with a high moment of inertia has a small angular acceleration whereas an object with a low moment of inertia has a larger angular acceleration. The reason for this is that if...
  11. G

    Conservation of angular momentum in scattering processes

    Greetings. So... let us consider a particle moving in the yz plane, coming from the infinite towards a region were a gravitational potential is appreciable. The Lagrangian of the system is \mathcal{L} = \frac{1}{2}\mu (\dot{r}^2+r^2{\dot \phi}^2) + \frac{G\,m\,M}{r} where \mu is the reduced...
  12. J

    Conservation of Momentum (Explosion Kinematics)

    Homework Statement [/B] A 3200 kg space vehicle (including a launchable lifeboat) is traveling with a velocity of 300 m/s in a straight trajectory [East]. The lifeboat (200 kg) is fired at a speed of 1000 m/s [N of original trajectory]. a) After firing it is found that the horizontal...
  13. M

    Spring conservation of energy problem

    1. A spring is suspended from a ceiling and a 256g mass is attached to it and pulled down to stretch the spring by 18.2cm The mass is released and travels through the equilibirum position with a speed of 0.746m/s. Calculate the force of the spring constant Solution Et= Et' Ee = Ek + Eg 0.5kx^2...
  14. S

    Pendulum Conservation of Energy

    Hi, I have a general question to pendulums. I hope it is ok to post it in this format. Please accept my apologies for my poor English. Homework Statement : As a general Example: I have a Pendulum of length L with Angle Theta as maximum displacement. I know how to solve these problems. Find...
  15. E

    Conservation of momentum and angular momentum

    Homework Statement 4 masses attached by a cross with no mass are spinning on a smooth table around the center of the cross. The distance between any mass to the center is L. The angular velocity is ω0. m1=m3,m2=m4 Suddenly, at t=0 (the time described in the picture), m4 disconnects from the...
  16. E

    Angular momentum conservation and center of mass

    Homework Statement Two bodies with an equal mass of M are attached by a pole with no mass with a length of L. The system is placed on a horizontal table and at first it is at rest. At t=0 a bullet with a mass of m hits the pole, as described in the picture. The collision is completely elastic...
  17. navneet9431

    Is it possible to apply energy conservation here?

    Homework Statement Homework Equations Kinetic Energy =1/2*m*v^2 Spring Potential Energy = 1/2*k*x^2 Gravitational Potential Energy = m*g*h The Attempt at a Solution I am thinking to solve this problem using energy conservation but I feel that it is not possible to apply energy conservation...
  18. Cc518

    Energy and momentum conservation

    Homework Statement An object with a mass of 5kg is placed on a horizontal surface and it has a semi-circular orbit with radius 1m. Its left end is close to a baffle fixed on the ground. A ball with a mass of 1kg is released from the point A by static. The surface and the groove are both smooth...
  19. T

    Kinetic energy & Conservation of energy

    Homework Statement You are driving with your car (of total mass: 1.2tonnes) with a speed of v=50km/h, until you see an obstacle. a) What is the kinetic energy of the car? b) When you start to brake, there is still 15m until the obstacle. What must be the size of the friction coefficient (µ)...
  20. F

    Conservation of Angular Momentum is Dumbfounding

    I find conservation of energy and linear momentum to be quite natural to understand, but I find conservation of angular momentum really, really tricky. Let me give two examples: (a) I call my system as a stick with identical springs at its ends, facing opposite directions, each spring is coiled...
  21. A

    Conservation of Momentum Space Ship Problem

    Homework Statement The payload of a spaceship accounts for 20% of its total mass. The ship is traveling in a straight line at 2100km/hr relative to some inertial observer O. When the time is right, the spaceship ejects the payload, which is moving away from the ship at 500km/hr immediately...
  22. K

    Conservation of momentum in two dimensions

    Homework Statement A bomb initially at rest is exploded into three pieces on a smooth, horizontal surface. Two pieces fly off at a 60° angle to each other, a 2.0 kg piece at 20 m/s and a 3.0 kg piece at 12 m/s. The third piece flies off at 30 m/s with an unknown direction. Determine the...
  23. G

    I Is energy-momentum invariant and/or conserved?

    Hi. I'm reading an introductory text that somehow seems to confuse if ##E^2-(cp)^2=const## means that the left side is invariant (under Lorentz transformations) or conserved (doesn't change in time). As far as I understand it, they only prove Lorentz invariance. Are they both true? If so...
  24. T

    Pair Production: Which Conservation Law?

    Homework Statement One of the reasons a single photon could not produce an odd number of electrons and positrons is a) energy would not be conserved b) unattainable photon energies would be needed c) matter would be created d) charge would not be conserved Homework EquationsThe Attempt at a...
  25. O

    Energy conservation and friction

    Hi, I just started learning physics at university and so I'm looking for help on a simple energy conservation problem. On the bottom right-hand of the image I attached below, you should see that it asks whether the initial speed would increase or decrease if the object was of a greater mass...
  26. L

    Simple Ice Skater with Conservation of Angular Momentum

    Homework Statement Not a HW problem, but a "me re-thinking things" problem. Please tell me where my thinking is flawed: You have an ice skater with no net external torques acting on him/her. (We are analyzing the time after they have to get an external torque on them by pushing off of the...
  27. S

    Conservation of angular momentum

    Homework Statement A uniform thin rod AB is equipped at both ends with the hooks as shown in the figure and is supported by a frictionless horizontal table. Initially the rod is hooked at A to a fixed pin C about which it rotates with a constant angular velocity w1 . Suddenly end B of the rod...
  28. C

    Conservation of Angular Momentum on a rotating disc

    I have a disc that is rotating due to air being blown at its outer radius. The incoming relative velocity of the air is high, therefore the effect of friction supersedes the effect of conservation of angular momentum. The tangential portion of this velocity decreases due to the friction as it...
  29. Krushnaraj Pandya

    Conditions for conservation of momentum

    Homework Statement Consider a classic wedge and block system, (block on top of wedge(inclination theta)). there is friction between the block and wedge (not enough to prevent block from sliding). All other surfaces are smooth. For the motion that follows after releasing the block from rest, is...
  30. J

    Angular momentum conservation in collision with a nail

    Homework Statement A ball of mass ##m## is attached to a massless string of length ##L##. The ball is released from rest as shown in the figure and as it reaches the bottom of the circle, the string wraps around a nail which is a distance ##d## below the center of the circle. What is the...
  31. W

    I Conservation of energy in an expanding universe

    I have read that conservation of energy is not a meaningful concept in an expanding universe cosmology. See here http://www.preposterousuniverse.com/blog/2010/02/22/energy-is-not-conserved/ However I have also heard the if the net energy os the universe is zero then it can have a vacuum genesis...
  32. sweet springs

    B Exploring the Concept of Energy in General Relativity

    I would like to understand better about the conservation of energy in GR. Let us think of infinitesimal vacuum volume dr\ sin\theta d\theta d\phi around the star in center. Light emitted from the star hit the bottom surface, r, of the volume. Say violet light photons hit the area 1 photon/1...
  33. DracoMalfoy

    Conservation of Energy: Spring PE: Toy gun on spring

    Homework Statement A toy gun is pointed toward the sky. A Styrofoam ball of mass 10g is at rest against a spring compressed 2cm. The spring is released causing the ball to move upward through the air to a max height of 1m. The air exerts a frictional force of 0.35N on the ball. What is the...
  34. D

    Accelerating charged particles and conservation of energy

    Hi I'm wondering how when a charged particle is accelerating it both emits energy in the form of em radiation while also gaining kinetic energy. All of that energy comes from the thing accelerating the charged particle, yeah? Is that necessary, like it is not possible to give a charged particle...
  35. mertcan

    Is Magnetic Flux Truly Conserved at the Interface of Air and Iron Core?

    Hi, initially I have read that magnetic flux is conserved in iron core, also I know divergence of B is zero but this conservation implies that there is no flux at the interface of air and iron core surface. We still magnetic field even at the interface so there must be flux. Why do we exclude...
  36. S

    I Spin and helicity conservation in QED

    Hi! I am kinda confused about what gets conserved in QED and what not. So the chirality is always conserved, I got that. So in the massless limit, helicity is too. Now in the massive limit. Are spin and helicity conserved? And if they are, are they at each interaction vertex, or just overall...
  37. archaic

    Maxwell's wheel and the conservation of energy

    We experimented with the Maxwell's wheel today and at the end we were asked about why does this apparatus stop since there is conservation of energy. I did some research and apparently there is a type of friction called "rolling friction", wikipedia defines it as "the force resisting the motion...
  38. velvetmist

    Oscillators and conservation of energy

    In the equation 7.4, the author is taking v0=√(C/M)*x, and I don't get where does that come from. I would really appreciatte your help, thanks.
  39. J

    Rotational motion: Conservation of energy doesn't work....

    http://www.animations.physics.unsw.edu.au/jw/rotation.htm#rolling I have set up an apparatus similar to what the above link says (the first bit about brass object with shaft). So basically, the shaft is in contact when the brass is first rolling, then it suddenly accelerates when the edge of...
  40. R

    Physics 30 question about conservation of momentum

    Homework Statement A space person is motionless a distance of 500m away from the safety of the spacecraft . The person has exactly 11.32min of air left and the person's mass is 103.2kg, including equipment. The person throws a phaser at a velocity of 50.2km/h away from the spacecraft in order...
  41. M

    Conservation of angular momentum

    Homework Statement A rod of length D sits at rest on a friction less table. A ball of mass M strikes the end of the rod with a speed V and rebounds with a speed 3v/4 causing the rod to rotate counterclockwise around a fixed axis at one end. The rotational inertia of the rod is I Homework...
  42. Aleoa

    Uniform circular motion and conservation of energy

    A point mass in an uniform circular motion is continuously changing the velocity direction. To do it, it continuously need force (energy). If we don't give any energy to the system it will anyhow continues its uniform circular motion. How it's possible, who gives the energy ? (It's seems a...
  43. Krushnaraj Pandya

    Energy conservation in an alpha-scattering experiment

    Homework Statement In scattering experiment, find distance of closest approach if a 6 MeV alpha particle is used 2. The attempt at a solution initially KE of alpha particle is 6 x 10^6 x e joules and 0 PE, finally its PE is kq1q2/d, k=9 x 10^9, q1=4e, q2=Ze=79e (assuming gold), d is distance...
  44. T

    Fluid mechanics: Bernoulli's equation and conservation of mass

    Homework Statement A mechanical servo-mechanism comprising of a movable piston-cylinder within a vertical cylinder operates based on a venturi contraction in a horizontal 350mm diameter pipe that delivers a fluid of relative density 0.95. The upper end of the 100mm diameter vertical cylinder is...
  45. C

    Other I can't solve questions related to conservation of momentum

    I'm a passout from school taking a gap year. I find the concept of conservation of momentum exceedingly difficult. Each question - and sometimes each part of a question, if a question has different parts - requires us to choose different systems each time. I look at the solution, and think I...
  46. jxj

    Isolating Variable in Equation for conservation of momentum

    Homework Statement So the problem is trying to isolate mA in the equation for momentum (only focusing on top formula, not bottom hehe) basically by solving the equation I assume. My teacher said because the vA and vB on the right were prime they could not be combined so I'm having trouble...
  47. S

    B Assumption of the conservation of energy to Heat Flow

    Recently looked at why temperature flows from high Temperatures to Low temperatures.Essentially it was laid on two Fundamental Assumptions: 1.Energy is conserved in the isolated system 2.Entropy in isolated non quasi static systems will always tend to increase. Lets take a brief look at...
  48. Jimmy Ridley

    Conservation principles and particle-particle reactions

    Please can someone help explain these to me? I have completed a-d but I'm not how e works. I thought gamma was an exchange particle so should it then decay further?
  49. S

    Is the following decay process possible?

    Homework Statement An antimuon and electron may bind together via Coulomb attraction and then decay, but is the following process possible? (µ+e-) → νe + νµ_bar *The νµ_bar is the antiparticle of the muon neutrino - the antimuon neutrino More than one answer (below) may be correct. a)...
  50. J

    Using conservation of energy vs. Newton's laws in a pulley problem

    The problem is attached in the photo. The correct answer, according to the teacher's solution, was obtained using conservation of energy. Initially I tried using Newton's law/kinematics and got the wrong answer. Why didn't this work? Can you ever use Newton's law/kinematics to solve pulley...
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