Sorry for typing error actually I was asking can gravitation field interact with matter in the absence of gravitons?if yes then does energy conservation hold?
Uh: "As expected, most of the DNA recovered from the feces samples in the study belonged to frog species and plenty of lizards, but researchers also found evidence that the bats were eating other bats and even a hummingbird".
I wouldn't say overly. The US Democrats lean more socialist than Republicans, but I don't think either are that socialist right now. Bernie Sanders for example leaned harder into that, but he didn't win the Democratic nomination.
Like most political terms, it's pretty malleable. Much of what US politics considers "socialist" (even as a self-description) would register as firmly center-left/social-democratic in many European countries.
And most of these Eurpoean social democrats would not describe themselves as socialists
Canada for example has generally more social programs than US (like universal health care) that even the right leaning side of Canada doesn't push back much on. The US seems to not really like that idea much, at least based on how reluctant they are to implement it. Even still, the most left leaning Canadian parties don't really describe themselves as "socialist" either.
He (the president) does have some power, but we cannot blame politicians for every problem the world has. Some people are evil, others are racists... it's easy to point a finger towards a single person but I think that even if we choose the best leaders in the world, everything would not suddenly get fixed. And the president is just a face chosen from the crowd, but a lot of the behind the scenes is run by many other people.
We can't blame politicians for every problem, but it's hard to fix some problems without going through the political system. Even if choosing the best leaders won't fix everything, but choosing better leaders is still generally a better option. The president is just a face chosen; but the character of the choice represents something about the people. And yeah, a lot of behind the scenes is done by others; but the president chooses a lot of those people; which can also be problematic.
When the corona was starting in Bulgaria, we had like 3 sick a day, and the minister was like "yeah sure, stop kids from going to school" and after 4 or 5 months of this, schools reopened. Now we have around 1400 sick a day and the minister is like "Nah, we ain't closing shit"
People have short memories, as soon as cases started to slow most countries thought that was the all clear and are experiencing worse second waves of covid
My side of Canada has done really well. I'm still so surprised and happy by how it's going here. Look at how flat this curve has been since May. novascotia.ca/coronavirus/data
@JingleBells People's voting behavior is usually a lot more varied and a lot less sophisticated than "this candidate/party/whatever's policies/character reflect what I want". Additionally, in many democracies without compulsory voting, voter turnout tends to be low enough that the non-voters make up the strongest "faction" - i.e. it is not ordinarily the case that the winners of a vote actually have the explicit support of a majority of the people they govern.
In unbiased estimators, we're trying to estimate some statistical value (mean, variance...) by only having a part of X, right? But does that mean that we can also compute the probability distribution of the sample (part) of X? And we use this partial probability distribution built from a sample of the whole X (that we don't know) to estimate statistical values? Is my understanding of unbiased estimators correct?
A lack of green and green would do pretty different things to eye receptors as far as I understand, so it kinda makes sense that the brain sees them differently. Also I think colours and combinations would be really weird if that happened. There would be two completely different ways to make green.
Sorry, I don't understand why when red and purple enter our eyes, we don't see green. Is it because no green eye receptors are firing so our brain doesn't know what to do so it invents a color?
An experiment that shows this would be placing a bouncy ball in a vacuum and letting it bounce up and down under gravity. Eventually it will stop since each time it hits the ground some kinetic energy is lost in the form of heat to the ground.
Energy isn't being lost either in an isolated inelastic collision, it's being transferred from bulk kinetic energy to microscopic kinetic energy if you like
That is "a physics way", when the two objects are travelling towards each other their kinetic energy is due to their bulk motion, $\frac{1}{2}mv^2$. Once they collide, if the collision is inelastic, some of that bulk kinetic energy is "lost" as it is transferred in the form of heat (which is microscopic movement) to the atoms of the two bodies.
So after the collision they two objects have less bulk kinetic energy than when they started, but the total energy hasn't changed, assuming the system is isolated.
the microscopic movement corresponding to heat is unordered movement where the particles move randomly in all directions, so the net momentum associated with thermal motion is zero.
@123 Note that there are two bodies involved here, $p = m_1 v_1 + m_2 v_2$. That overall kinetic energy is reduced does not mean you can't find $v_1,v_2$ so that the momentum is still the same.
@123 One thing to notice is that KE depends on $v^2$, not just $v$, so the values of $v$ where initial KE = final KE so you shouldn't expect them to align fully with the values where initital momentum = final momentum
the microscopic movement corresponding to heat is unordered movement where the particles move randomly in all directions, so the net momentum associated with thermal motion is zero.
@SirCumference Yeah, but that's just not true when more than one body is involved
A loss in total KE doesn't mean a decrease in speed at all. If one body is like a hundred times more massive than the other and I take 50% of the energy and give it to the second body and throw the other half away, the second body will be a lot faster than the first was with the full energy.
(note that these specific numbers are likely not a valid solution for conserved momentum :P)
@ACuriousMind K.E and P both has mass and velocity dependent only. If K.E change means either mass or speed would change. mass is constant. There must be speed reduce in term of heat so KE change.
How it is possible momentum conserved if speed changed.
@123 If both bodies have the same mass $m$, and one is initially at rest while the other moves with $v$, then in a perfectly inelastic collision they'll stick together after the collision and both move with $v/2$. The initial momentum is $m \cdot v + m\cdot 0$, the final momentum is $m \cdot v/2 + m \cdot v/2$, so momentum is conserved even though the speeds of both bodies changed!
@123 You have $\frac 1 2 m v_{1i}^2 + \frac 1 2 m v_{2i}^2 = \frac 1 2 m v_{1f}^2 + \frac 1 2 m v_{2f}^2$ compared to $mv_{1i} + mv_{2i} = mv_{1f} + mv_{2f}$ The combinations of $v_f$ and $v_i$ that make each side equal can be different for momentum than for kinetic energy, so from the math it should kinda make sense that momentum can be the same on each side while kinetic energy no longer is.
Intuitively let's say we have a very heavy body and a very light body. If we reduce the heavy body's speed, we've greatly reduced the system's KE (since it's so massive). But if we reduce the light body's speed by the same amount, we haven't reduced the system's KE by as much
I could keep the KE the same by decreasing the heavy body's speed by a little, and consequently increasing the light body's speed by a lot
but if you compute the KE for this scenario, it's initially $\frac{1}{2} m v^2$ and after the collision it's $\frac{1}{2}m v^2/4 + \frac{1}{2}m v^2/4 = \frac{1}{4}mv^2$, so KE was not conserved
@ACuriousMind L.H.S (before collision) = R.H.S (after collision) in your KE equation and this should be equal, but you take before collision $\frac{1}{2} mv^2$ separately.
It is possible for you guys. Give me one example with calculation where momentum and KE along with in same example. and also explain the physics. Thank you
I wonder the equality sign in KE equation before and after collision.
@ACuriousMind In your KE comment. I assumed you take $\frac{1}{2}mv^2 + \frac{1}{2}m(0^2) = \frac{1}{2}mv^2$ because first body is moving with speed v and second body is at rest before collision.
According to my calculation in your example energy is also conserved.
In case if i accept by experiment, if bot bodies stick together total mass becomes $m = m_1 + m_2$ but $m_1 = m_2$ , Total mass $= 2m$ So, $\frac{1}{2}mv^2 + \frac{1}{2}m(0^2) \neq mv^2$ , The equality does not hold.
Also i accept by experiment we observed, We take $\frac{1}{2}v$. Then, $$
Also i accept by experiment we observed, We take $\frac{1}{2}v$. Then, $\frac{1}{2}mv^2 + \frac{1}{2}m(0^2) \neq \frac{1}{2}m (\frac{1}{2}v)^2 + \frac{1}{2}m(\frac{1}{2}v)^2$
