?

I'm asking this because of an exercise I had to do from my textbook.

It says: Classify each statement as an observation, a law, or a

theory. One of the statements is "Matter is made of atoms."

According to the answers key, that statement is a theory. Of course, I understand that such a statement attempts to explain WHY chemical reactions happen, so it makes sense for it to be a theory. Yet a few pages before, my textbook claimed that atoms can now be seen through an Atomic force microscopy (AFM).

So, I'm now wondering, why can't that statement classify as a law with this new evidence? It is a direct observation of atoms, thus it could well become a law, right?. After all, seeing something from a microscope is not so different from seeing it with the naked eye.

Shouldn't this statement be like the law of gravity nowadays?

Thanks for the help.

I'm getting a bit confused when classifying matter between compounds and homogeneous mixtures.

I understand that the difference between the two is that compounds are CHEMICALLY bonded molecules, while mixtures are PHYSICALLY bonded substances.

Yet thinking about it, it's difficult for me to say (without looking online or experimenting with a microscope) if metal alloys are a mixture. In my mind, the bronze vase I have in my living room seems chemically uniform. I can't tell the copper apart from the tin. It looks like a pure substance; a compound.

However, I search online and I find out metal alloys are (homogeneous, most of the time) mixtures. How can you know that? Is trying to separate or alter the substance/s the only way to come up with that answer? Or am I overlooking something important, and the whole issue can be resolved rationally?

I'm usually alright until I enter and the examiners start asking me questions.

It's just that knowing that I shouldn't take too much time in answering a question just gets me more nervous.

Could anyone suggest a tip to control those nerves?

It'll soon be Mother's Day in my country, and I'd like to get my mother a nice present.

The thing is, I always give her clothes/jewellery etc but I want to give her something less superficial this year. Something she could use at home, to ease her housework or cooking, for example (all these things usually tire her out).

I already did a personal photo-album-thingy a few years ago, so that option's out.

Any ideas? Only thing which came to my mind was the Roomba vacuum cleaner, but that's so expensive to purchase...

Thanks in advance!

When the Moon orbits between our planet and the Sun, we get the New Moon and the Waxing/Waning Crescent Moons, right?. If I understood this right, that is when we can see the Moon at day time.

What I don't get is why, if the day time side of the Earth can see it during those phases, shouldn't the night time side of the planet not be able to see it at all during those days? But I've never heard anyone say that the Moon can't be seen in the night sky.

Thanks for the help, hope I was clear enough.

Don't think my title is clear enough, so let me explain.

I'll have to solve for different kinds of undetermined limits in my exam, but the thing is, I can't differentiate between the limits that have a possible answer and the ones that don't.

Let me illustrate it with an example:

lim (x^2 - 1) / (x-1)

x -> 1

If I substitute 1 for x in this case I get 0/0. However, if I substitute x for very close numbers to 1 (like 1.000001 or 0.999999) I realize this function doesn't have a limit, because those close numbers bigger than 1 go to infinity while those a bit less than 1 go to minus infinity.

Now consider this limit:

lim (2x-2)/(x-1)

x->1

Again, if I substitute x for 1 I get 0/0. Yet this time, when I replace it by very close numbers to 1, I see it has a limit: 2. Actually, if I factor the polynomial ( (2*(x-1))/(x-1) ) I get 2 too.

My question is, how can I know in advance if an undefined limit will actually exist or not? I don't want to waste so much time substituting x with my calculator.

Thanks! 10 points to the BA! :)

Don't think my title is clear enough, so let me explain.

I'll have to solve for different kinds of undetermined limits in my exam, but the thing is, I can't differentiate between the limits that have a possible answer and the ones that don't.

Let me illustrate it with an example:

lim (x^2 - 1) / (x-1)

x -> 1

If I substitute 1 for x in this case I get 0/0. However, if I substitute x for very close numbers to 1 (like 1.000001 or 0.999999) I realize this function doesn't have a limit, because those close numbers bigger than 1 go to infinity while those a bit less than 1 go to minus infinity.

Now consider this limit:

lim (2x-2)/(x-1)

x->1

Again, if I substitute x for 1 I get 0/0. Yet this time, when I replace it by very close numbers to 1, I see it has a limit: 2. Actually, if I factor the polynomial ( (2*(x-1))/(x-1) ) I get 2 too.

My question is, how can I know in advance if an undefined limit will actually exist or not? I don't want to waste so much time substituting x with my calculator.

Thanks! 10 points to the BA! :)

I'm studying the Industrial Revolution, and I can't understand how the Bourgeoisie suddenly appeared and accumulated capital.

Were they nobles, traders, or peasants?

If they were inferior nobles, why did they care about innovating and increasing production?

If they were traders, how could nobility let them not work their land?

If they were peasants, how did they free themselves from the compulsory rural tributes?

Thanks for the help!

So far I've only used the "i" to denote the square root of -1, and I don't know how to do this exercise to be honest. Is there any way to separate the root?

All I could do was break up the root like this:

4√1 · 4√-1

1 · 4√-1

And I'm stuck with the same thing again. Or is this as far as I can get, therefore I have to name the fourth root of -1 in a different way?

I can't understand how, when using either the product or expenditure approach, you can realize whether certain goods are final or not.

For example, flour. It can be bought as an intermediate good (for making bread) or by households as a final good (say, to make a birthday cake). Now, how can you know, when considering the flour sales, which bags of flour were sold to whom?

That's all I want to know. Thanks.

My textbook says a market is at equilibrium when "No individual can do any better doing anything different". Then it says that a market is efficient when "All existent opportunities of individuals doing better without others doing worse are taken".

I'm really confused.. where exactly do these concepts differ from each other? Furthermore, if they're so similar, then is a market at equilibrium always efficient and viceversa?

Thanks for the help! (I feel really stupid having trouble with economy basics)

First, why is the accumulation of goods inventories considered an Investment? I understand it will turn into money in the future, once they're bought, but wouldn't we be counting the same products twice, once they're actually bought?

The other thing is, how are the value of these goods in the inventories measured? By the market price? Because after all, they still haven't been bought, so its price may go higher or lower than it is at the moment of calculating GDP.

Thanks!

Just wondering. I'd really love to show books which exemplify my point, and the cover helps to legitimate it. However, I don't have the copyright to use any of the pictures of the books.

What can I do?

Is it ok if I put it on my blog acknowledging it isn't mine? After all, I'm actually doing publicity to the books...

I'm trying to expand my knowledge of chemistry, but unfortunately, I feel like all I've been taught at school is so abstract.

There are some basic, easy concepts which I STILL don't quite grasp the intuition of... specifically:

· Matter, Mass, Volume, Weight

· Particle, Substance

· Relativity, Space & Time (I need to really get the notion of these last three so I can understand the Big Bang theory).

I'd love it if someone could help me out by giving me an easy (as less technical as possible) definition of these words. I know they are a lot of concepts, but I sometimes tend to confuse them :/

I'll award 10 points to the best answer so as to reward the effort.

Thanks in advance!

It's my first time trying to do one of these. Bear with me, English is not my native language so it might've come off as too basic.

This is the assignment: (Taken from the College Board website)

"Think carefully about the issue presented in the following excerpt and the assignment below.

Many persons believe that to move up the ladder of success and achievement, they must forget the past, repress it, and relinquish it. But others have just the opposite view. They see old memories as a chance to reckon with the past and integrate past and present.

Adapted from Sara Lawrence-Lightfoot, I've Known Rivers: Lives of Loss and Liberation

Assignment: Do memories hinder or help people in their effort to learn from the past and succeed in the present? Plan and write an essay in which you develop your point of view on this issue. Support your position with reasoning and examples taken from your reading, studies, experience, or observations."

Essay:

It is an obvious fact that memories derive from our lives' experiences. However, according to some people, these memories are important to keep in mind for one's future development, whereas others argue that one must forget these feelings (specially if they did not have a desirable outcome for the person) in order to progress.

On the one hand, it is worth looking back on the past, because the road we takes makes us better. In other words, we learn from every step we take, and this recollection of knowledge along the way helps us avoid repeating the same mistakes over and over, therefore making us more successful (as we are less prone to make those same mistakes).

On the other hand, there is no point remembering a dreadful mistake which can drag our self-esteem down. In those cases, a better response would be to just focus on the present and look forward to the future.

In summary, both points of view are acceptable. It is probable that looking back on past memories depends on each individual. Possibly, persons with roughly any belief in their own capabilities prefer not thinking about the past, while people who take pride in both their good and bad past experiences certainly do prefer it.

Feel free to point out all my mistakes or better ways to express the ideas. I was planning to make it more formal, but the topic didn't really help :S

Anyway, 10 points to whoever can help me. Thanks!

I'm a rookie in the field, I've just started studying it. It is unbelievably interesting, yet I really need to know I'm grasping it all correctly.

My main concern is about Utility and Pay-offs. I keep hearing the terms over and over in class, but are they any different from each other? They look like synonyms to me...

Help would be really appreciated. Thanks!

Any Youtube video out there? (Or any of you guys willing to explain this to me lol)

I know I can learn them by memory, but I'd just forget it in the long run. So, if someone could help me understand where they came from, I'd be glad.

I have that 1/(2√x) = 1/2 x^(-1/2).

How is that possible? Why is x to the NEGATIVE one half power? I understand that the square root of any number is that number to the POSITIVE 1/2, right? What am I not getting from this?

I know this is a stupid/simple doubt, but I'd be glad if someone helped me out. Thanks!

I learnt the asimptotes before studying limits. And now I'm confused.

Will the limit always be equal to the vertical asimptote?

Thanks in advance for the help.

It's like all the stuff I can find on Youtube was made by either religious fanatics or atheists, trying to impose their views.

Anyone know a more objective video of this controversial topic? Something that pays attention to both sides of the argument, and is not trying to convince the spectator with it?

Thanks!