Scientific notation: toggling back and forth on the TI-30XA

In high school, the tutor had a calculator much like the TI-30XA. For scientific notation, there’s probably none better.

What some people call the “normal” way to write a number, is also known as “float”. So 1.35×10-3 is 0.00135 in float.

A real advantage of the TI-30XA is its way of toggling back and forth between scientific notation and float. If you’re in scientific, press 2nd 4 to change to float; from float, press 2nd 5 to get back into scientific notation.

Let’s say right now you’re in float. You want the number 32350 in scientific notation. Just key it in, then press 2nd 5. You’ll see it’s now in scientific: 3.235 04. Press 2nd 4, and you’re back at 32350.

Of course, to enter a number that’s already in scientific notation, you use the EE key. Therefore, the proper way to enter 3.21×105 is as follows:

3.21 EE 5.

Personally, I really enjoy the TI-30XA’s ability to toggle back and forth between scientific notation and float so conveniently.

HTH:)

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Chemistry: what is enthalpy?

The tutor introduces a topic that academic chemists love.  Enthalpy appears in high school chemistry.

The definition of enthalpy, H, is

H=Eint+PV

where Eint is the internal energy content of the product, while PV is work done by volume increasing against pressure (relating to gases) as the reaction proceeds. Note that enthalpy is called by the variable H rather than E.

What does enthalpy mean, conceptually? For the concept to be useful, I think the internal energy content is the important part to focus on. After the reaction that forms a given substance is over, the PV part vanishes. The substance’s internal energy content is then what might distinguish it from another substance in terms of enthalpy.

Ethane (C2H6), which is found in natural gas, has a standard enthalpy of -84.68 kJ/mol. Oxygen gas, O2, has a standard enthalpy of 0. CO2 has a standard enthalpy of -393.5 kJ/mol, while H2Ogas has -241.8 kJ/mol. The precise numbers aren’t important. The point to realize is that when ethane burns thus:

2C2H6+702→4CO2+6H20

you can perceive the reaction as a change in enthalpy like so:

molecules 2C2H6 702 4CO2 6H20
enthalpies (kJ/mol) -84.68 0 -393.5 -241.8

Notice that, from left to right, the enthalpy values decrease.

When you’re near a natural gas heater that’s burning, the enthalpy being lost is released to the environment: it’s the heat you feel. What’s actually being lost is internal energy from the fuel’s bonds as they are broken and replaced with lower energy ones. A reaction that has negative enthalpy change, aka, -ΔH, releases heat to the environment. A reaction with +ΔH draws in heat from the environment. In that case, the heat is used to form higher energy bonds than the original molecules had; the products’ internal energy goes up.

HTH:)

Sources:

www.energy.alberta.ca/naturalgas

Mortimer, Charles E. Chemistry, sixth Ed. Belmont: Wadsworth, 1986.

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Bullying: the ubiquitous menace

The tutor weighs in on bullying.

This morning I was told it’s pink shirt day.  Since I’m known for wearing pink anyway, my wife pointed out that I should wear it today.  I built an outfit around a hot pink sweater:  it was great.

I love wearing pink because, when I was a kid, I was bullied for not being “manly”.  I was one of those skinny boys with no apparent muscles.  I took abuse for that from elementary school right into my twenties.  I was never seriously hurt, but the bullying took its toll.

At school, there was no rule against bullying when I was a kid.  Physical fighting wasn’t allowed, but social bullying was wide open.  If you were being bullied, that was your problem.  You either had to solve it, or just “take it.”

Social bullying is, supposedly, frowned upon today.  Yet, it seems unlikely to stop. Bullying is expressed through unkindness, which can be effective even when it’s very subtle.

One problem with confronting bullies is that, of course, they are generally gifted in some way.  Many I faced as a kid were physically gifted with strength.  Social bullies are gifted with an awareness of how to gain approval from the “right people” – and how to use that approval as ammunition.  They are smart, and attractive.  That’s a pretty tough combination to go up against.

What bullies gain from being so, is a question I’ve pondered.  I think in the end, bullying is a waste of time.  It’s a symptom of talent mixed with immaturity.

I think the best defense against bullying is love at home.  If a child knows they’re loved and cherished, and that they will be welcomed home, I think that child can survive just about anything.  Let’s hope that all children can count on that.

Happy pink shirt day:)

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

English: verbs: finite vs non-finite

The tutor was never taught these terms in school.  However, what if someone asks about them…?

You could be a great writer without knowing the terms finite verb and non-finite verb. Yet, books sit on shelves, waiting to explain these obscure terms. Clearly they’re important to somebody.

Fundamentally, an academic believes that knowledge sitting quiescently in a book will serve useful if learned. In that spirit, let’s take a few minutes to find out about finite and non-finite verbs.

A finite verb is an action word being used as the action in a sentence:

They run each day before lunch.

In the sentence above, run is the finite verb.

A non-finite verb is an action word being used not as an action, but perhaps as a noun, adverb, or adjective:

She hired a coach to get feedback on her running.

Although running comes from the verb run, the word running functions as a noun in the sentence above.

Another name for non-finite verb is verbal. (See my post on verbals here.)

Perhaps, being mindful of the names of the various word constructions can help open the writer’s mind to possible ways to construct a given sentence.

HTH:)

Source:

Hodges, Horner et al. Harbrace Handbook for Canadians. Scarborough: Nelson    Education Ltd, 2003.

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Lifestyle: the first weekend of yard work, 2015

The tutor discusses his commencement of yard work in 2015.

I hear that, on the eastern half of the continent, winter has been tough.  People have shown me pictures from the States, I think, of snow drifts as high as the front door.  I haven’t verified them; I never watch the news.  From what I’ve heard, though, this winter has been possibly even harsher than last year’s – in the East.

Here on the West Coast, we’ve had a different story:  this may be the warmest spring in ten years.  Back on January 25 (see my post about it here), we had, by my reckoning, our “first day of spring.” This past weekend, we had sun with highs in the double digits both days. The flies were buzzing and the birds were singing. I even got circled by a robust yellow jacket a few times.

True enough: unlike my comrades back East, I haven’t had to shovel the driveway lately. However, with spring weather comes yard work.

My wife and I built a new landscaping wall last November; from that, I had heaps of earth left on the lawn that needed clearing. We have enough bushes and trees so that there is pruning to do December through March. The front chip bed needed raking. The lawn needed liming. The old lawn mower needed starting….

I was out there Saturday and Sunday. Clearing the earth from the lawn, then moving it to other parts of the yard, took about six hours. The pruning didn’t take long, but the fire to burn the prunings took a couple of hours’ tending. The chip raking took around 45 minutes; the liming, around the same.

My lawn mower is an old Lawn-Boy from 1978. (I mention it in my post on horsepower and kilowatts.) At the start of the season it’s always a challenge to start; this year it took around 130 pulls of the cord. I’ve been told part of the problem is that I don’t put stabilizer in the gas in the fall. I don’t know for sure; I’ll have to research that for another post.

Anyhow, the mower always does start; indeed, it finally did in Saturday’s dusk, after 20 minutes of sweat. It hunted around for a couple of minutes to find its right RPM; from then, it ran like a top. I walked it around the back yard, doing a first pass over some strong patches of lawn so they don’t get away from me in the coming weeks.

Through twilight, I could see the kids’ TV on in their downstairs lounge. When I was a kid, the idea would have been that the kids should be mowing the lawn, while the adults relax. Did I feel that way? Not a chance. Part of being older is knowing that, outside on that early spring night, I was getting the better deal. Some day, they’ll be just where I was, and thankful to be there:)

To my cohorts on the West Coast: good luck with your spring cleanup:)

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Windows: a little batch programming towards a friendly greeting

The tutor has wanted to place a greeting at the top of the Windows terminal (aka command prompt screen).  Now you can too.

I heard about batch files – and saw files with the .bat extension – in the late ’90s. They weren’t necessarily new then; that’s just when I first saw them.

A batch file is a plain text file that sends specific commands to other programs in the Windows system. It might tell one to open, for instance. It may also order the backup of a file.

This little batch project consists of two programs: one (called p1.bat) opens the command prompt, then initiates the second one. The second one (p2.bat) prints a friendly greeting, then the date, atop the command prompt screen.

p1.bat
@echo off
cmd /k p2


p2.bat
@echo off
echo Hello. Hope you’re well:)
date /t

In p1.bat, cmd opens the terminal, while /k keeps it open. p2 calls p2.bat to start.

In p2.bat, echo prints the message that follows to the screen. date outputs the date, while /t suppresses the option for the user to change it.

@echo off means that the actual commands are not printed to the screen, but just executed.

As I can tell, batch programming uses the newline as a command separator.

Batch programs need to be written in plain text, so not with a word processing program (unless you know how to switch its output to plain text). In Windows, the plain text editor is Notepad.

To write a batch program that opens the terminal and just prints “Cheers:)” at the top of the screen, you’d open Notepad and type a little file:

@echo off
cmd /k echo Cheers:)

Just to be safe, you probably want to press enter at the end of the line – although it may not matter.

Save the file as cheers.bat. You’ll probably want to give it its own folder.

To execute the file, find it in its folder (using the file manager, rather than the terminal), then double click it. Hopefully, the command prompt screen opens up with the friendly greeting Cheers:) at the top.

I’ve used some very helpful sources for this article:

superuser.com

microsoft.com

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Financial math: interest rate conversions on the HP-10B

A lifetime ago, the tutor studied financial planning.  That’s when he got acquainted with the HP-10B.

Of the financial calculators I know, the Hewlett-Packard HP-10B is potentially the easiest to use.

One feature of particular value to anyone in financial math is interest rate conversions.  Let’s look at how they’re done on the HP-10B.

Example 1:  Find the effective annual interest rate if the nominal rate is 3.1% compounded monthly.

Solution:  On the HP-10B, there is an orange key on the left side, second from the bottom.  You press it to access the orange function printed above a given key.

In this case, we know the nominal rate is 3.1%. We type in 3.1. Next, we press the orange key, then the I/YR key (above which is printed NOM%).

To tell the calculator the compounding is monthly, we type in 12, then press the orange key, followed by the PMT key – which, you’ll see, has P/YR printed above.

Now, we press the orange key again, then the PV key. Above PV, you’ll see EFF%.

The answer 3.14 appears across the screen. Apparently, the nominal rate of 3.1% compounded monthly is the effective rate of 3.14% compounded annually.

Now, let’s imagine you know the effective annual rate, but you want to convert to a nominal rate.

Example 2: Find the nominal rate, with weekly compounding, of 4.2% compounded annually.

Solution: This time, we know the effective rate of 4.2% compounded annually. We type in 4.2, then press the orange key, then the PV key. Next, we type in 52, the orange key again, then the PMT key. Finally, we press the orange key, then the I/YR key. The answer 4.12 appears. Apparently, the rate of 4.2% compounded annually is equivalent to a nominal rate of 4.12% compounded weekly.

I’ll be covering more features of the HP-10B in future posts. HTH:)

Source:

HP-10B Business Calculator Owner’s Manual. Corvallis, OR: Hewlett-Packard, 1988.

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

English: equivocation: a logical fallacy

What might a tutor read casually?  Here’s the latest.

Although I have a degree in math, I’ve been told that “logic” and math are different. Logic, it seems, is more often claimed by English and philosophy students.  So be it.

Today I pulled my Harbrace Handbook for Canadians off the shelf, simply because I haven’t looked in it for a while.  I opened it to a random page and got schooled on a new concept: equivocation.

While equivocation has other meanings, the topic I landed at was logical fallacies. In that context, equivocation is the assumption that when one meaning of a word applies, its other meaning does as well. Here’s an equivocation:

All you’ll find in the trash is trash.

Given society’s fascination with abandoned articles and what treasures might be found among them, we can probably agree that All you’ll find in the trash is trash is not necessarily true.

What makes All you’ll find in the trash is trash an equivocation is that trash has two meanings:

1)  Trash comprises articles that people throw away.

2)  Trash comprises articles that have no value.

Both meanings don’t have to apply simultaneously; we’ve all heard of valuable items being found amongst trash.  Furthermore, what seems valueless to one person might be prized by someone else.

The point Harbrace makes:  A student should take care not to use such an argument in an essay; the reward will likely be red ink.

HTH:)

Source:

Hodges, Horner, et al.  Harbrace Handbook for Canadians.  Scarborough:  Nelson        Education Ltd., 2003.

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Programming: what is event programming?

In this post, the tutor speaks from experience, rather than formal education.

Event programming (aka, event-driven programming), as I understand, focuses on designing interfaces that react to user input. What happens when the user clicks a button? What happens when they press enter? Specifying what should happen – then making sure it does – is event programming.

You could pose the idea that video game programming was the first event-driven programming. However, I’d argue that event programming as we know it today barely existed when I was in university (I got out in ’95). That’s because nowadays it seems inextricably connected with web design.

This post contains a little example of event-driven programming. On the choice menu below, you can select a color, then click the button to change the text of this paragraph to the color you’ve chosen.

Event programming is often coded in Javascript. It’s another computer language I’ll be discussing in future posts.

PS: Event programming is not to be confused with event planning, which is well beyond the tutor’s experience:)

Source: w3schools.com

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.

Perl: alphabetizing a list of command line arguments

The tutor returns to the perl sort function.

Back in my post on November 27 I introduced a perl program that finds the median of a list of numbers. It depends on perl’s built-in sort function to put the numbers in order.

Not only does perl’s sort work for numbers, but also for words. The syntax for numbers is

sort{$a <=> $b}@array_of_numbers

while the syntax for words (aka strings) is

sort{$a cmp $b}@array_of_strings

The cmp in the strings syntax is itself a built-in function that compares strings.

Here’s a brief program that orders a list of words it receives from the command line:

#!/usr/bin/perl

@array_in_order=sort{$a cmp $b}@ARGV;
print “\n\nHere is your list of words in alphabetical order:\n\n”;
foreach $one(@array_in_order){
print “$one “;
}
print “\n\n”;

Running the program from the terminal, you enter the list of words after the program name with just spaces (not commas) between. Suppose you save the program as

alphasort.txt

and want to run it on the list

apple xylophone holiday beeswax packing

From the proper directory you key in

perl alphasort.txt apple xylophone holiday beeswax packing

then press enter.

I’ll be talking more about the perl sort function, string comparisons, and much else in coming posts. HTH:)

Source:

Robert’s Perl tutorial

McGrath, Mike. Perl in easy steps. Southam: Computer Step, 2004.

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.