Author Archives: hangtime

Calculating Standard Deviation & Variance

This video gives you a taste of just how laborious, tedious, and annoying statistics can be -- but also how easy calculators make stats -- by introducing you to one of the larger square root equations you'll ever see. I mean seriously, sigma notation INSIDE of a giant square root, with BOTH i's and n's... It doesn't get better than that!

This video appears on the page: Standard Deviation & The Normal Distribution

Standard Deviation & The Normal Distribution
Calculating Standard Deviation & Variance
Standard Deviation & Normal Distributions

This chapter introduces standard deviation, tells you what the heck it is and how to calculate it, and relates it to the normal distribution.

Part of the course(s): Chemistry-General ,Physics

Kelvin Scale & Absolute Zero

Absolute zero. Not only is it super-cold, it spawned a whole new temperature scale -- with no negative temps -- and a whole new way to lose points on chemistry and math problems -- using Celsius rather than Kelvin! Wow, way to go absolute zero.

This video appears on the page: Temperature

Converting Between Celcius and Farenheit

This isn't rocket science, but it's still pretty confusing when you're watching a soccer game or the Olympics and they're talking about it being hot because it's 30 degrees outside but you're like 30 is really cold not hot but then that's when you realize that they're probably in Europe so it's Celsius so that probably is pretty hot, like the man said, even though you're not sure of the conversion factor. Yeah, it's like that.

This video appears on the page: Temperature

Temperature & Absolute Zero
Converting Between Celcius and Farenheit
Kelvin Scale & Absolute Zero

Converting between degrees Fahrenheit, Celsius, and Kelvin. Also covered: absolute zero, and why you always want to use Kelvin for gas problems.

Part of the course(s): Middle School Math ,Chemistry-General ,Physics

Buoyancy

It's easy to say, "The buoyant force is equal to the weight of the fluid displaced," but it's much harder to apply that to boats, boulders, submarines, balloons and bricks that may or may not be in a foam cooler. Lots to cover here, but after this you won't look at a boat the same way again!

This video appears on the page: Density & Buoyancy

Density Calculations

After the previous video introduced the concepts of density, this video is all about calculating actual numbers. Not only will we calculate density, but we'll rearrange the density formula to solve for volume and mass as well. Also covered: hard mixture problems where you have to find the density of a mixture.

This video appears on the page: Density & Buoyancy

Density In Gases, Liquids & Solids

In this first video we'll get into what density means, and the densities of some common liquids, gases and solids. We'll also dig into why things float, and how liquids and gases can "float" on top of each other based on their relative densities and specific gravity.

This video appears on the page: Density & Buoyancy

Density & Buoyancy
Density In Gases, Liquids & Solids
Density Calculations
Buoyancy

This chapter covers the general concepts of density and buoyancy, as well as how to calculate density and flotation forces on submerged and floating objects.

Part of the course(s): Middle School Math ,Chemistry-General ,Physics

Multi-Step Unit Conversion Problems

Unless you've watched the previous two videos about dimensional analysis, I wouldn't recommend this one! But once you're ready, this video covers how to do multi-step conversion problems, meaning conversions which require two or more conversion factors to solve. At the end there are a couple of super-hard problems, and we'll discuss the way to approach crazy hard problems.

This video appears on the page: Unit Conversions & Dimensional Analysis

One Step Unit Conversion Problems

This video demonstrates a ton of basic unit conversion problems -- kilograms to grams, meters to millimeters, years to days -- as well as some funky word problems. What all these problems have in common is that only one conversion factor is needed to get the answer.

This video appears on the page: Unit Conversions & Dimensional Analysis ,Free Sample Videos ,physics free videos ,ACT Prep free videos ,free Accuplacer prep videos ,TCI free videos ,SAT Free Videos

How To Pick Conversion Factors

The aspect of dimensional analysis that tends to trip students up the most is picking conversion factors, so we'll take a crack at that all by itself in this video. We'll also talk about the theory of unit conversions (aka how the heck this stuff works), and figure out the easy way to decipher conversion factors cleverly hidden in word problems.

This video appears on the page: Unit Conversions & Dimensional Analysis

Unit Conversions & Dimensional Analysis How To Pick Conversion Factors
One Step Unit Conversion Problems
Multi-Step Unit Conversion Problems

The process of converting units, often called Dimensional Analysis, is one of the most important skills in science, and like sig figs you'll need it for the rest of the year.

Part of the course(s): Middle School Math ,Chemistry-General ,Physics

Accuracy vs Precision

Not a terribly difficult or important topic, but I made this video because every single chem teacher in the world seems to put this as a multiple choice or short-answer question on their Sig Figs test. So it's worth knowing.

This video appears on the page: Sig Figs & Rounding

How Many Sig Figs Should My Answer Have

In this video we'll perfect the art of figuring out how many sig figs you're supposed to put in your answer. It's up to you to remember to do this on EVERY PROBLEM you do for the rest of the year if you don't want to get a C. (I know I'm gonna get some email for this, but you should just assume your chem teacher is mean and plan to execute flawless sig figs accordingly.)

This video appears on the page: Sig Figs & Rounding

Rounding Decimals to Proper Sig Figs

Let's put it all together and use our decimal rounding skills to round decimals to the appropriate number of sig figs! How are you supposed to know what the appropriate number of sig figs is? That's the next video.

This video appears on the page: Sig Figs & Rounding

How Many Sig Figs Does This Number Have

The whole point of this Sig Fig stuff is to be able to state your answers to the appropriate accuracy, or significant figures. But before you can do that, you've got to be able to tell how many sig figs are in the number to begin with! These are their stories.

This video appears on the page: Sig Figs & Rounding

How To Round Decimals

Whether you're in pre-algebra or College Chemistry, rounding decimals is something that you can't afford to mess up. So if you have trouble with this, in this video I'll show you the sure-fire way to not mess up, and how to avoid the most common mistake I see.

This video appears on the page: Sig Figs & Rounding ,Decimals

Sig Figs & Rounding Decimals
How To Round Decimals
How Many Sig Figs Does This Number Have
Rounding Decimals to Proper Sig Figs
How Many Sig Figs Should My Answer Have
Accuracy vs Precision

Sig figs. This chapter will teach them to you, but it's your job to remember to use them in every answer for the rest of the year or you'll lose half your points. Seriously.

Part of the course(s): Middle School Math ,Pre-Algebra Class Page ,Chemistry-General ,Physics

Polar Graphs You Should Memorize

Not every teacher makes you memorize these, but if you have to graph polar equations on a quiz or test, it will help you a lot to have these committed to memory. Limacons, cardoids, flowers, petals, even vs odd... If you know the simple patterns to spot, you too can set the curve on your next trig quiz.

This video appears on the page: Polar Coordinates