word choice - Difference between 重い and 重たい

In some situations everybody around me use 重い, and when I went to the bicycle shop everyone was only using 重たい.

Both mean heavy, but what is the difference in meaning or context between them?

Can something be 重い but not 重たい? Or 重たい but not 重い?

Answer

重たい is supposed to be used when talking about personal opinions (subjective), while 重い is for general usage (objective).

But that said, when someone uses 重たい in a situation, another person may use the same word unintentionally because they are very similar.

Personally, I think 重たい has more feelings than 重い because you can stress the sound "たい", so it is like saying that you know how heavy it is by experience.

words - naming a school headquarters

I study a martial art called Geido Kenpo Ninpo Ryu. Having said this, what should a Honbu for this martial art be called?

I see for Judo the Honbu is called the Kodokan. Would there be a similar term for Geido Kenpo Ninpo Ryu?

minhag - Are there any Yekkish wedding customs specifically?

In Yekkish Ashkenaz minhag are there any wedding customs distinct from general Ashkenaz wedding customs?

For example, I've read online that there is a minhag to use the chattan's tallis for the chuppah and that Yekke authorities did not object to getting married in shul (whereas Polish Ashkenazi authorities considered it chukos ha'goyim because Christians often married in churches). Are there sources for these or other customs?

computational chemistry - Determine rate equations for entire kinetic scheme

I am working with the following kinetic scheme that represents pyrolysis of a biomass particle:

The paper that discusses this scheme provides the following rate constants:

• K1 for the pathway of $\text{Biomass} \rightarrow (\text{Volatiles + Gases})_1$


• K2 for the pathway of $\text{Biomass} \rightarrow (\text{Char})_1$


• K3 for the pathway of $(\text{Volatiles + Gases})_1 \rightarrow (\text{Volatiles + Gases})_2 + (\text{Char})_2$

The rate equation provided in the paper for the conversion of biomass is $$\frac{\mathrm d\,B}{\mathrm dt} = -(K_1 + K_2)\,B$$

The rate equation for the char 1 component is given as $$\frac{\mathrm d\,C_1}{\mathrm dt} = K_2\,B - K_3\,C_1$$

And finally the rate equation provided for the char 2 component is $$\frac{\mathrm d\,C_2}{\mathrm dt} = \delta\,K_3\,C_1$$

where $\delta$ is a deposition coefficient reported as 1.45 in the article. Note that all components of the system are on a mass basis such as $\mathrm{kg/m^3}$.

It is fairly straightforward to calculate the concentrations of $B$, $C_1$, and $C_2$ at each time step given an initial concentration of $B$. However, I would like to determine the concentrations of the volatiles and gases in the system too. Since it doesn't seem possible to calculate the individual volatile and gas components from the given scheme, I would like to determine the concentration of the (Volatile + Gases) group which could be labeled as G. So how would I develop the overall rate equations for B, C, and G?

$$ \frac{\mathrm d\,B}{\mathrm dt} = -(K_1 + K_2)\,B \\ \frac{\mathrm d\,C}{\mathrm dt} = K_2\,B + ? \\ \frac{\mathrm d\,G}{\mathrm dt} = K_1\,B + ? $$

Answer

The Biomass-equation is: $$\frac{\mathrm d B}{\mathrm d t} = -(k_1 + k_2) B$$ The (volatile + gases)$_1$ equation is: $$\frac{\mathrm d VG_1}{\mathrm d t} = k_1 B$$ The (volatile + gases)$_2$ equation is equal to equation for (Char)$_2$: $$\frac{\mathrm d VG_2}{\mathrm d t} = \frac{\mathrm d C_2}{\mathrm d t} = k_3 C_1$$ (It might be that it needs to be multiplied by 1/2.)

And the equation for (char)$_1$ is this: $$\frac{\mathrm d C_1}{\mathrm d t} = k_2 B-k_3 C_1$$

The equations for the complete set of (char)s and (volatile+gases)s are then the sums of the solutions for $C_1$ and $C_2$ resp. $VG_1$ and $VG_2$.

---

For initial concentration of $B(0)=1$ and everything else $f(0)=0$, as well as $k_1=2$, $k_2=10$ and $k_3=3$, you should get something similar to this:

number - What are the 30 Mitzvot for Bnei Noach?

What are the 30 Mitzvot (Commandments) that Bnei Noach have accepted (based on Hullin 92a)?

שלשים מצות שקבלו עליהם בני נח.‏
Thirty commandments which Bnei Noach accepted upon themselves.

Answer

Rabi Menachem Azaria from Pano says that the Thirty commandments is sections of the 7 commandments (עשרה מאמרות, מאמר חקור דין חלק ג פרק כא).

Rashi on the Gmara says that we don't know what is the list of the 30 commandments.

See also the Talmud Yerusalmi (מסכת ע"ז דף ט,א פרק ב הלכה א גמרא) that says in the future Bnei Noach get 30 commandments. Maybe this is the meaning of Ula.

tefilla - Making Everyday Like Yom Kippur

I have toyed with the idea of importing an aspect of Yom Kippur into my everyday life and am constantly looking for (homiletically) a connection which would draw the essence of Yom Kippur into every day life. I think I have found one and am looking for sources which might have made this connection before (and more eloquently than) I have.

One thing which makes Yom Kippur unique is that during it, there are five shmoneh esrei-prayer services (maariv, shacharit, musaf, mincha and ne'ilah) as distinct from weekdays (3 Amidah services) and holidays (4).

However, when one sees the Chazarat Hashatz repetition as a distinct prayer experience, then daily, one experiences 5 prayer services (3 b'Lachash and 2 Chazarat Hashatz, at least as subject of fanciful homily).

Are there any sources which draw together the 5 shmoneh esrei services on Y"K and during every day?

halacha - Is it forbiden to drive a car?

I remember reading an answer here saying that it was forbidden (even for men) to drive a car. That one Rabbi used to forbid it. I tried to search it but I did not find it. Maybe someone can help.