# 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. ### Why does the given conserved quantity mean the motion is on a cone?

TL;DR Summary: . An electrone moves in a magnetic field ##B(\vec r)=g \frac {\vec r}{|\vec r|^3}##. Why does the conservation of the quantity $$\vec J=\vec r \times\vec p +eg\frac {\vec r}{|\vec r|}$$ mean that the motion is on the surface of a cone?
2. ### Spring momentum conservation problem

For this problem, The reason why I am not sure whether it is a valid assumption whether momentum is conserved because during the collision if we consider the two masses to be the system, then there will be a uniform gravitational field acting on both masses, and a spring force that is acting...
3. ### Why is momentum not conserved?

Here is question + drawing.
4. ### I Why momentum is conserved when a gun fires? (conceptual question)

I understand that conservation of motion comes from the action and reaction pairs of newton's third law. When it is triggered, two forces appear that cancel when analyzed as a system. My question is how is it that momentum is conserved if before the shot there was no force in the system and...
5. ### I What do you need to establish that spin is conserved?

Hi. Question as in the summary. Spin has no obvious classical interpretation but it is often a conserved quantity and considered as some sort of angular momentum. What do you need to establish that spin is a conserved quantity? I'm finding references to situations where spin is not a...
6. ### Conservation of Energy when lifting a box up off the floor

So, I cannot for the life of me write a conservation of energy statement, when an object is lifted up by a force. So in my example there is a box on the floor with v = 0, and then a force of magnitude F, where F > mg, acts on the ball, now the net force is F-mg, and hence the work done is (F -...
7. ### Solving Orbital Speed with Energy & Angular Momentum Conservation

I've already solved the orbital speed by equating the kinetic and potential energy in the circle orbit case. $$\frac{1}{2}mv^2 = \frac{1}{2}ka^2.$$ And so $$v^2 = \frac{k}{m}a^2$$ Now when the impulse is added, the particle will obviously change course. If we set our reference point in time...
8. ### Do different length ramps violate conservation of energy?

mgh=(1/2)(m)(v^2) gh=(1/2)v^2 sqrt(2gh)=v Should have the same v, but this is not the case based on the answer and real-life experiments.

12. ### Conservation of relativistic energy, collision of particles

Question: With maximum do they mean that the speed of the pions is the same as the proton and an antiproton? Otherwise there will be two unknowns, and if I use both relativistic-energy and momentum conservation equations I get difficult equations.
13. ### Helium balloon energy conservation

For this problem, How can energy be conserved if the bit highlighted in orange is true? Many thanks!

17. ### Puck collision with rod using angular momentum conservation

For this problem, Why for part (a) the solution is, Is the bit circled in red zero because since the putty is released at a very small distance above the rod it velocity is negligible? Also for part (d) the solution is I did a computation of the initial and finial kinetic energies of the...
18. ### I Conservation of charge in the Universe

The charge of an isolated system is conserved. This implies the charge of the universe is constant. This implies that charge can neither be created nor destroyed. This implies that the net positive charge and the net negative charge of the universe are conserved. Is this right?
19. ### Discovering Vector Direction in Conservation of Energy Problems

For this problem, Is the length vector into or out of the page and how do you tell? EDIT: Why must we use conservation of energy for this problem? I tried solving it like this: ##IdB\sin90 = ma ## ##IdB = ma ## ##v_f = (2aL)^{1/2} ## ##v_f = (\frac {2dIBL} {m})^{1/2} ## Which is incorrect...
20. ### Which system to apply conservation of momentum to?

For this problem I was very confused whether conservation of angular momentum should be applied to the person, the swing or the person-swing system. It seems to me that there is no net torque on any of the three systems I listed above. However, it seems that the angular momentums of the three...
21. ### The direction of flux vectors in derivation of conservation of mass

In the derivation of the conservation law of the conservation of mass, the flux on one side enters and the flux on the other side leaves the control volume. I presume this is due to the assumption that the volume is infinitesimally small and hence v(x,y,z,t) will not change directions...
22. ### I Conservation of Energy in GR: A-B System Analysis

Assume you have a two particle system, A, which has a mass and gravitational pull of g, and B, an object with low mass, The system starts at time 0 with the distance between A and B being 0, A being at rest and B having enough kinetic energy to move it a distance r away from A, until time t all...
23. ### Surely this will NOT work: violation of conservation of momentum?

The rotating ball should push the vehicle first to the right and once it hits the airbag - to the left?? Even if this works, how are you going to automate it and repeat it?
24. ### I Are SM B & L conservation violations through sphalerons possible?

It isn't often that you see this many bold claims in a five page Letter, the abstract and citations of which appears below. The conclusion I find most interesting is this Letter's conclusion that contrary to the current consensus understanding of the mathematics of the Standard Model (mostly...
25. ### I Charge conservation and special relativity

If conservation of charge gets violated in future experiments, what would be the implications on relativity? I have some faint idea that this will cause photons to have non-zero rest mass, but does this affect special relativity at all? Also, does special relativity make conservation of charge...

44. ### Conservation of energy problem with friction included

so I haven't looked at the solution yet, but I know that a 100% the velocity needs to be bigger, but analytically, I get a - sign instead of a + sign as you'll see at the final square root. So for the first 15meters of the motion all you should know is that ##v_1 = 10.458 m/s##. for the 2nd...
45. ### Car-Car System: Energy Conservation?

this is an easy problem but would it be possible to consider car-car system. What I did on paper was carsystem and because they have the same properties(mass en speed) multiply by ##2## solution for car-car-earth system I assume is the following if it is possible? solution for car-car: law or...
46. ### B Conservation of Momentum for system of particles

We know that if we take two particles and assume no external force is applied then by Newtons third law total momentum gets conserved after collision. If we take three particles and there is collision between them and no external force then the momentum is again conserved for each pair like in...
47. ### B Conservation of momentum and conservation of energy details

If we have a ball with mass m dropped from a height h down to the ground, how come we can't set the conservation of energy equation just as the velocity of the ball turns 0. mgh = 0 If instead the ball were moving with an initial velocity v, would the equation be ##mgh + \frac{1}{2}mv^2 = 0##...
48. ### Conservation of momentum problem (sand-spraying locomotive)

If I consider only the freight car's mass and the mass dm that's added to the freight car as part of the system, then I get this answer: https://ibb.co/QfKSqQ5 But if I consider the freight car's mass, the mass dm, and the locomotive car as part of the system (maintaining the locomotive has...
49. ### B Catapult Energy Conservation

This is the catapult. At equalibrium the spring is 0.09 meters in length. When its fully stretched out its 0.225 meters long and I place a rock (0.205 kg) close to where my finger is on the catapult. The catapult starts with this much energy because 1/2 * k * x^2 90.54 is the spring constant...
50. ### Conservation of Energy in Trampoline Bounce

I was able to calculate the correct answer (given by a solution sheet), V=5.364 m/s, using the momentum impulse equation, P0+J=Pf. If this value is correct, however, I don't understand how energy is being conserved. The speed increases after the person bounces off the trampoline while the mass...