# Country Boy

Senior Members

614

1

1. ## Square Root Prove

For a given positive number, a, both x=√a and -x= -√a satisfy the equation $x^2= a$ and are called "square roots of a". The square root function, √x, however, in order to be a function, must have a single value and that is defined to be the positive value. "The" square root of x^2 is |x|.
2. ## Square Root Prove

No! Especially since you used the word "technically". Technically, $\sqrt{x^2}= |x|$. That is x if $x\ge 0$ and -x if $x< 0$,
3. ## Square Root Prove

a= -2. a2= 4. What is the square root of 4? (Remember that the square root is a FUNCTION so can have only one value.)
4. ## What is mathematics?

Physics is the study of mass, motion, and the relations between them. Chemistry is the study of elements, compounds, and the relations between them. Economics is the study of goods, prices and the relations between them. ... Mathematics is the study of relations in the abstract.
5. ## Total newb question

All motion is relative to some fixed point. You van is traveling at 60 mph relative to the road. The fly is traveling at some much lower speed relative to the van. It speed relative to the road is very close to 60 mph (slightly more when it is flying forward, slightly less when it is flying back) but since it is flying in the enclosed air in the vehicle the fly doesn't notice it. (If the car were to accelerate the fly might wind up plastered to the back window- acceleration is not relative.)
6. ## Quick relativity of simultaneity and length contraction thought experiment

You said that the train's "rest length" is 100 m. Then in the train's frame of reference the two lightening strikes are 100 m apart. Of course, in the track's frame of reference, the two lightening strikes are 1 m apart. Yes, that is the same question as the "tunnel" question. In the train's frame of reference the tunnel is 100 m long. In the track's frame of reference it is 1 m long. (Who would build a tunnel one meter long?!) I don't know what you mean by "abstract distance". Any distance, pretty much by definition, can be measured, as well by a meter stick as any other way.
7. ## How can you get a negative value from the Magnitude formula

No, there shouldn't. While, for any positive number, a, there exist two values of x, one positive and one negative, such that $x^2= a$, $$\sqrt{a}$$ is, by definition, the positive one only. That is why, when writing the solutions to
8. ## What experimental verification exists to substantiate that light from a receding light source travels at c to a relatively stationary destination?

"Relatively stationary"? Relative to what? "Receding light source"? Receding from what? I assume you are referring to an observer who is, of course, stationary relative to himself, observing a light source receding relative to him. The measurement of the speed of light, with light from whatever source is probably the most repeated experiment in physics.
9. ## How big is a point? (Can be that the Natural Numbers are Finite?)

I think that ConciousEnergy, saying "in space" is confusing mathematics and physics. In mathematics a point is defined by its position. It has NO "area" or "volume". Talking about a "point in space" you are talking about physics and when you apply mathematics to physics it only matches approximately,
10. ## why 0/0 is NOT defined?

If 0/0= a then 0 X a= 0 is also "well defined". a/0, for non-zero a, is "undefined" because if we set a/0= b then a= bX0= 0 which is not true. 0/0 is not defined because if we set 0/0= b then 0= bX0 for any b. Many people say 0/0 is "undetermined" rather than "undefined". But there is no good reason to set it equal to 0.
11. ## What is exactly up and down (unfinished)

Swansont: Yes, but like all such things it is not useful until everyone has agreed on a specific interpretation. That was done with "up" and "down" on earth long ago! Sirflappington: I would argue that in space there is NO "up" and "down"
12. ## Fidelity at different time

Few people will be willing to down load multiple files with no idea what is in them. Is it really too much trouble to type your problem? Then I guess it is not very important.
13. ## How big is a point? (Can be that the Natural Numbers are Finite?)

It's NOT a law, it is a definition. A geometric point is not a physical object. It is an a mental concept that identifies a position and has no other properties.
14. ## would you help me with future perfect?

B says that, at some time in the future, I will have made 3 cakes and that I willstill have all three. A say that, at some time in the future, I will have made 3 cakes but that I might have disposed of (ate, gave away, threw away) one or more of them,
15. ## What is "base-2 number system"?

11, our standar "decimal system" is base 10. We have 10 digits, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 and create all numerals using those. For example immediately after "9" is 10= 1*10+ 0, then 11= 1*10+ 1, then 12= 1*10+ 2, etc. In "binary" we have only two digits, 0 and 1 and create all numerals using the. For example immediately after 1 is 10 which can be read as "2 and 0", then 11= 2+ 1= 3, then 100= 4+0*2+ 0*1, then 101= 4+ 0*2+ 1*1= 5, then 110= 4+ 1*2+ 0*1, etc. Notice that, just as 10,100, 1000, 10000 are "powers of 10" so in binary, 10= 2, 100= 4, 1000= 8 are "powers of 2".
16. ## Which countries have their own cryptocurrency?

What do you mean by "have cryptocurrency"? If you mean "It is posssible to get some kind of cryptocurrency in that country" then they all do. If you mean "the country's government officially recognizes some kind of crytocurrency to be as negotiable as its regular currency" then none do!
17. ## Today I Learned

They are, however, biologically, the same plant! Yes, a shamrock is a clover with three leaves. Rarely the clover will have four leaves in which case it is called a "four leaf clover" rather than a "shamrock".
18. ## Sign rule for multiplication

-2(3+ (-3))= -2(0)= 0 So, by the distributive rule -2(3)+ (-2)(-3)= 0 Add 2(3) to both sides (-2)(-3)= 2(3).
19. ## Can be that the Natural Numbers are Finite?

The problem is that you say you are talking about mathematics but you are actually talking about physics. You do not know what mathematics is and you do not know what physics is! There is "infinity" in mathematics but there is no "infinity" in physics.
20. ## How he died? 1000 ways to die #316

English IS my native language and even to me that sentence is nonsense!
21. ## Need help with some calculations on amounts.

An hour? You expect a response within an hour? The samples were 500 g and you are asking about 1 kg= 1000 g so 2 samples. 1.2-1.5 mL=1.2- 1.5 g were aded to each sample so 2.8 to 3 g must be added to 1 kg. The liquid added was 2% trehalose so 2.8*.02- 3.0*.02= 0.056- 0.06 g of trehalose.
22. ## Making jelly (that's jello in USA I believe)

No, "Jello" is a brand name- for a type of gelatine, not jelly. (Unless "jelly" is used in England to mean gelatine rather than a fruit spread for bread.)
23. ## Velocity and acceeration [ Vector calculus with applications ]

y as a function of x, yes, $$y= a cosh\left(\frac{x}{a}\right)$$. But this is s, the arclength, as a function of $$\phi$$, then y as a function of x, yes- y= a cosh(x/a). But this is s, the arclength, as a function of phi, the angle the graph makes with the x-axis. It is the "Wethwell equation"- Catenary - Wikipedia
24. ## Derivative problem from old book, is the answer a typo, if not, why not?

Notice that the author does NOT use the same "dot" for multiplication and a decimal point. Multiplication is indicated by a centered dot ($2\cdot 4$) while the decimal point is on the baseline (2.4).
25. ## Derivative problem from old book, is the answer a typo, if not, why not?

You, yourself, said, in your first post, "The author uses a dot for multipllication and as a divider between the ones column and the tenths column" (I would have said "as a decimal point"). In this problem the author is using it as a decimal point but you are interpreting it as a multiplication.
×