Do all organisms perceive the passage of time at the same rate? | AskScience Blog

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Sunday, August 20, 2017

Do all organisms perceive the passage of time at the same rate?

Do all organisms perceive the passage of time at the same rate?


Do all organisms perceive the passage of time at the same rate?

Posted: 19 Aug 2017 09:18 PM PDT

Or would a minute seem longer for a frog than a ferret, for example?

submitted by /u/perimason
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Is it possible to have a "reverse" Placebo effect?

Posted: 19 Aug 2017 02:47 PM PDT

Which means even after you take a functional pill, it just won't have any affects, just because you think it is a Placebo pill. Thanks in advance

submitted by /u/RafikiTheWiseBaboon
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Why did the radiation from Hiroshima not last as long as the chernobyl disaster?

Posted: 20 Aug 2017 05:35 AM PDT

Was it the power of the explosion blowing the radiation away or was the bomb designed in such a way as to avoid long lasting fallout?

submitted by /u/the_wild_skunk
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Would a helium filled drumset sound higher in pitch or just not work?

Posted: 20 Aug 2017 02:47 AM PDT

In case you're wondering, no, I didn't find anything on Google

I do have a drumset, just not the helium

And sorry for the stupid question :')

submitted by /u/Chouras56
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[LONG][CONFUSION]Violation of Lenz's law in magnetic interaction between a conducting ring and a moving magnet?

Posted: 20 Aug 2017 07:11 AM PDT

This post is going to be a bit long, but mostly because I am going to explain all the math behind my confusion. Feel free to skip the math to reach the conclusion. I have marked different sections in the post for your convenience. Please go through the effort of reading this, as this is really nagging my mind and I have gone through some effort to type this out too ;)!

THE PROBLEM

In our physics class we were posed this question: Suppose a magnet whose dipole moment is M is located on the axis of a conducting ring of radius a and resistance R, at a distance x from it's centre. The magnet is moving with a velocity of v towards the ring. This is the figure. What will be the force on magnet? It is given that a may not be very small compared to x.

THE SOLUTION

Since a is not very small compared to x, we cannot use the inverse cube laws for field due to a dipole. So what we did was, we replaced the magnet with a ring with radius b very small compared a, with a current of i2 through it. Now we calculate the mutual inductance between the two rings. Since b is very small in comparison to a, mutual inductance comes out to be

uoa2πb2/(2(a2+x2)3/2)

(We get this by calculating flux due to field of ring with current i1, linked with the ring which replaces the magnet, then dividing this flux by i1.)

So to get the flux due to field of magnet on the original ring, we simply multiply this mutual inductance by i2 (current through the ring which replaces the magnet). So we get flux as

uoi2a2πb2/(2(a2+x2)3/2)

But i2πb2 = current x area = magnetic dipole moment of magnet = M

So flux due to magnet through the ring is

uoMa2/(2(a2+x2)3/2)

Since x is changing (the magnet is moving), this changing flux through the ring produces a current due to induced emf in the ring.

This current will be emf/R = time derivative of flux / R.

So differentiating the value of flux which we calculated, we get the current in the ring as

i = 3uoMa2xv/(2R(a2+x2)5/2)

Now, this current produces a magnetic field B = uoia2/(2(a2+x2)3/2 at x distance from it's centre on its axis.

So we put in the value of i to get magnetic field due to ring on the magnet M.

B = 3uo2Ma4xv/(4R(a2+x2)4)

Potential energy of magnet M is U = -M.B = MB. And force on the magnet is F = -dU/dx

So putting in value of B in MB, and differentiating with respect to x, we get

THE CONCLUSION

F = 3uo2M2a4v(7x2-a2)/(4R(a2+x2)5)

So this is the force due to ring on magnet.

THE CONFUSION

Now here in lies my confusion. This formula should work for all values of x. So when we plug in values of x smaller than a/sqrt(7), we get the force on the magnet to be attractive! But lenz's law says it should be repulsive. Now our physics teacher explained the reason behind it:

The magnetic field lines when the magnet is close to the ring looks like this. Notice the some of the field lines cross back into the ring plane. So the magnetic field lines is a mixture of "dots" and "crosses" through the ring. So at some point, the rate of increase of dots counters the rate of increase of crosses, and thus the ring develops a south pole when looked from the magnet, and thus the ring attracts the magnet.

Now this seems a perfectly legit explanation, and the math checks out, but I have a huge question regarding this.

Suppose the magnet is given a velocity v towards the ring at a distance of a/sqrt(7) from the centre of the ring. The ring will attract the magnet, as proved above. When the magnet crosses the centre of the ring, there is a current flowing through the ring AND the velocity of the magnet is more than v. So obviously the energy of the system has increased, with no source of energy input, rather, there is dissipation of energy due to current. Where does the extra energy come from? Is this a violation of law of conservation of energy?

submitted by /u/rusty_ballsack_42
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How do spiders survive in dark isolated areas?

Posted: 19 Aug 2017 05:40 PM PDT

Everyone is familiar with basement spiders or abandoned building cobwebs. My question is: How do these arachnids survive (and seemingly thrive) indoors in the dark away from any abundant food source (bugs)?

submitted by /u/pawsibility
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Does a Faraday Cage needs to be grounded to effectively work?

Posted: 19 Aug 2017 06:23 PM PDT

My concern on this question is especially in the case of microwave oven. Does it matter for signal leak if the microwave is grounded or not?

submitted by /u/Finnthebroken
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Do any wild organisms have a symbiotic relationship with another to babysit their young?

Posted: 20 Aug 2017 02:02 AM PDT

Is there some species that plays host to effectively keep vulnerable young animals together and away from predators until the parents vocalize a call and the offspring retreats to them? Like a hollow plant nursery that wants fertilizer or sharing a kill with something that has its own young that can occupy the other's young's time?

Earth is amazing, I refuse to believe no organisms have cashed in on this small stretch in behavior or morphology.

submitted by /u/pimpmastahanhduece
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Why do we get eye gunk?

Posted: 19 Aug 2017 06:21 PM PDT

I was wondering specifically why we get eye gunk while sleeping or at least why it's there when we wake up.

I'm confused as to how it's produced, what it really is, and the purpose behind it - is it just to keep eyes shut? If so can eye gunk be produced with prolonged periods of shut-eye whilst still mentally awake?

submitted by /u/ury17
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How long does a beam in the Large Hadron Collider last before they have to dump it?

Posted: 19 Aug 2017 03:50 PM PDT

I read online 10-20 hours but I'm not sure if that's outdated information.

submitted by /u/TheIncorporeal
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Why is wind louder when you face it and quieter when it goes directly into your ear?

Posted: 19 Aug 2017 07:45 PM PDT

Is it possible for an object in space to be stationary?

Posted: 19 Aug 2017 07:26 PM PDT

To clarify, is it possible for an object that is beyond the gravitational pull of a planet or other large object to remain stationary, relative to everything else that is orbiting or otherwise traveling? Thank you for indulging the ranks of the ignorant.

submitted by /u/GustavoShine
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Understanding Energy from Lagrangian mechanics?

Posted: 20 Aug 2017 03:59 AM PDT

For a long time, I've tried to understand what energy is, and why it's conserved, given that force could be created and destroyed, why is it that certain systems would have a quantity that defines it's ability to transfer work and it's always conserved. Besides Noether's theorem, how does Lagrangian mechanics explain why energy is always conserved? To me, analyzing various systems would give me great detail of the topic, if certain forces are applied there usually is another force(s) that opposes it(mechanics: friction, electrodynamics: Lorentz), how does this fit into Lagrangian mechanics?

submitted by /u/BRP106
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What is happening on a cellular/tissue level when someone loses their voice?

Posted: 19 Aug 2017 05:04 PM PDT

Why is there a post-storm haze?

Posted: 19 Aug 2017 06:14 PM PDT

After the thunderstorm and tornado warning today, the general outdoors seemed brighter than normal and had a green hue to it. I only remember seeing this once before, also after a storm. Is the storm the cause, and if so what is happening? (flair added tentatively, not sure where this fits but it needed one)

submitted by /u/TechnoEnder
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Because of gravity's constant effects, is there infinite energy in the universe?

Posted: 19 Aug 2017 11:31 AM PDT

So it's been a while since i've taken a physics course, but the last one I did take was grade 11 physics. One of the major units we learned about there was energy, and a big part of that was the kinetic vs potential energy balance. Now we also learned that energy is always conserved so it cannot be created or destroyed, but this never sat quite well with me.

Say we have two apple trees. One at the top of a hill, and one at the bottom of the hill. The trees grow their apples, and when they are ripe enough they fall to the ground. Now the apples at the bottom of the hill just fall straight down to the ground and stop, but the apples at the top of the hill fall straight down, and then roll down the hill. This means that for the apples on the top of the hill, they have a greater potential energy before they fall, and greater kinetic energy during the fall and subsequent roll.

Now normally you have to lift something up against the force of gravity, for it to gain potential energy, but in this case, there is no extra energy expended to put the apples in a higher location gaining that extra potential and kinetic energy. In other words, both apple trees are expending the same amounts of energy to grow the apples, but the ones of the top of the hill will generate more energy when falling, purely because of their location.

So it seems like in this scenario, we have a situation where two of the same objects have differing levels of energy based off location in space, but no energy input was required to create that difference in location. And because energy cannot be created, my only explanation for this is because of gravity's constant force on everything with mass, there is infinite energy.

Sorry for the long post, but I hope this can be answered as it's really bugging me. Thanks.

submitted by /u/Warriorjrd
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Why dont all polar liquids act the way ferrofluid does?

Posted: 19 Aug 2017 03:15 PM PDT

Ive been told that ferrofluid works because in a magnetic field, tge magnetic poles of the suspended magnet line up, attracting in the direction of the field and repelling orthogonally. In that case, why dont electrically polar liquids like water have the same reaction in an electric field?

submitted by /u/chunkylubber54
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Why does rifling help bullet accuracy?

Posted: 19 Aug 2017 09:18 AM PDT

How are closed-loop steel cables used in e.g. ski lifts made?

Posted: 19 Aug 2017 12:56 PM PDT

Is it first made as a long cable that is then closed in a single place, is it woven in a more continuous way, or is it made in a different way?

submitted by /u/MrShortcut
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