Sloth Sanctuary

Everyone knows I support the Child's Play charity, but I do contribute to others as well. If you are looking to do some good and help out a group that gets little notice but does fantastic work, check out the Sloth Sanctuary in Costa Rica. A little bit goes a long way there and if you can skip a couple of lattes one week, you might consider sending them the savings. They are having a year-end drive that ends on Jan. 1 that could use some propping up:



and you can send them some scratch through Razoo (very nice online fundraising service) by clicking on the image. If you're like me and prefer to help out those that a trillion people aren't giving to already, consider the Sloth Sanctuary. You can give anytime by visiting their site and making a direct donation to this great group.

Hope the break is going well - see you soon!

And Off We Go...

Today was a day of finishing tests and snatching up some bonus points. What I did is put up to 5 points from your bonus work onto your last test and if you got more than 5, I dropped it onto homework. So, happy holidays from me...

When we return, be ready to launch into new material and don't lose sight of the fact that midterms start not long after we get back from break. You have your notes, tests, review sheets, homework, etc., so do not put off studying for that exam, which goes back to Day 1!

Test Day!

Oh what fun it is... everyone was engaged in their Chapter 9 exams and, hopefully, all loose ends will be securely tied off before we leave tomorrow. When we return, be prepared to hit heat and topics like heat transfer, change of phase, latent heat, specific heat and all sorts of other goodies...

Big Ol' Review Day

Tomorrow is the Chapter 9 exam for everyone and today was set aside to tie up all loose ends. We walked through the chapter page by page and addressed any issues that folks had with the material. Email me tonight (early!) or stop by tomorrow before school if you have any additional questions. When we return from break, we'll be jumping into the topics of heat and thermodynamics and that should take us right to the midterm exam!

A Bunch of Hot Air

Everyone was working on gases today, among other things and that wraps up the new information for the chapter and Wednesday's exam. B and E Blocks discussed the ideal gas law and its derivations (Boyle's, Charles's and Gay-Lussac's laws) and the homework problems tonight focus on working with the ideal gas law. I posted one video over the weekend (9.4 #4) and here's another to help you work through some of the ideas:

9E #3



C Block reviewed their gas law homework, then began a practice test that we will use as part of our exam review tomorrow. F Block went over the same homework, but then moved to the buoyant forces lab that allowed them to see the variation in pressure with depth in a column of fluid and work with the pressure-with-depth formula (which was a special case of Bernoulli's equation for static fluids). We'll go over the lab in class tomorrow and walk through the chapter as part of our review for Wednesday's exam.

For all blocks, when we return from break, the topic of interest will be heat, so prepare for a little bit of a gear change...

Yeah!

Child's Play charity is just poised to break 2 x 10⁶ k! That's 2 million smackeroos for the exponentially challenged. I just put in my contribution of some DS games that were on Boston Children's Hospital wishlist at Amazon. Looks like lots of locals really opened their wallets this year. I looked at the wishlist early in the season and what remains is only a fraction of what was there. Glad to see that local gamers did their part to help with the cause and make some sick kids a little happier this year...

Gas Law Problems

Here's a worked out example to help with the work we'll go over tomorrow...

9.4 #4

Center of Mass

When an object's center of mass is positioned beyond the object's base of support, the object will tip. Glad to know people are out there making practical use of this principle for the benefit of mankind...

Problem-Solving Help

Here are a couple of videos for tonight's homework (for C, E and F at least)

9D #1




9D #2




9.3 #3

Good old' Bernoulli

Folks were working with Bernoulli's Principle or equation in class.  B Block springboarded from their pressure with depth lab into the ideas associated with fluids in motion.  We. looked at types of fluid flow, the ideal fluid model and then looked at how conservation of mass in moving fluids is this field by the relationship outlined by the continuity equation.  We'll go into conservation if energy in fluid systems tomorrow. with was the ground trod by C, E and F Blocks.  Those classes reviewed Bernoulli's  Principle and the continuity equation and pressed forward with Bernoulli's equation.  Bernoulli's equation is a mathematical statement that energy in a fluid system is conserved.  Energy can be bound In kinetic energy, gravitational potential energy and pressure.  The energy can be converted from one form to another any number of times and not all forms may be present at different points in the system.  We'll review all of this and the associated homework tomorrow, so do your best working with the ideas and formulas. Then, it is on to properties and behaviors of gases.

I Made a Video!

Finished watching the new Fright Night film (not bad - David Tennant rules, as usual) and tried out a new app on the iPad. Click the Play button to see what I cobbled together in an unedited round for the continuity equation. Maybe I'll try and keep up with doing some videos, especially if they actually let me make the background dark. I hate white backgrounds...

Fluids are Moving and Grooving

C, E and F Blocks began a discussion on fluids in motion. We took time to contrast laminar and turbulent flow, described the ideal fluid model, discussed conservation of mass (as satisfied by the continuity equation) and dabbled in Bernoulli's Principle. Bernoulli's Principle explains a number of phenomena in real life that we outlined in class and a few more examples will be added tomorrow. Bernoulli also provides us with Bernoulli's equation, which will demonstrate how fluid systems satisfy the Law of Conservation of Energy.

B Block conducted a lab investigation on variations in fluid pressure with depth. The linear relationship derived from the experimental data nicely corroborated the basic pressure with depth formula: P = P_o + ρgh. We took time to examine the parts of that equation as demonstrated in the investigation and will take time tomorrow to see if you were able to successfully transfer that experience into problem-solving techniques for your homework problems. Then, it's onto fluids in motion!

Catching Up

Me... not you...

With my absence yesterday, today was a day to take up the slack, tie up loose ends and cover some new ground while we were at it. B and E Blocks reviewed and spot-checked understanding for buoyancy and began a walk through the topic of pressure. We took time to define pressure, contrast it from force, discuss Pascal's Principle and its application to hydraulic devices and explain how and why pressure varies with position in a column of fluid. Tomorrow, we'll put the icing on pressure and begin to take a look a fluids in motion. Well, E Block will do this - B Block will be investigating pressure with depth and the absolute pressure formula: P = P_o + ρgh - and using that to further their discussion of fluid pressure.

C and F Blocks tidied up their work with fluid pressure. C Block conducted a lab investigation that verified the linear relationship between pressure and position in a fluid column and saw that the equation of the line for that experiment was simply the formula for absolute pressure that we worked with in class. Some additional pressure-depth practice problems were assigned for practice and all of this will be reviewed tomorrow before we move on to fluids in motion. F Block discussed the idea of pressure with depth and how that could be extended to the effects on living creatures that we observed when they are exposed to significant variations in environmental pressure. Tomorrow, we move from stationary fluids to fluids in motion and see how that motion affects fluid pressure and direction of motion.

Hipsters...

...they're everywhere...

Friday is Happy Day!

B block reviewed their rotational dynamics exams and then moved onto their buoyancy homework problems. That took a bit more time than expected and we took the safe course of working on a few more before moving on to new material. On Monday, we'll start off by looking at these additional buoyancy problems before moving onto fluid pressure.

C Block checked over their pressure problems and then took a look of how fluid pressure varied with depth in the fluid column. Atmospheric pressure is highest at ground level since all the layers of the atmosphere pushing down on your head. As you rise, there is less mass, therefore weight on you, so the pressure diminishes. The same is true when you descend in the ocean. And because objects are 3-dimensional, the pressure on the bottom of the object is larger than the pressure on top of the object, ensuring a net upwards force. There is the origin of the fluid's buoyant force... we'll go over your homework problems on Monday and then tackle the topic of fluids in motion.

E Block investigated Archimedes Principle. For a completely submerged object, the buoyant force is basically constant. But, as you progressively submerged the object, the buoyant force increased as the volume of the displaced fluid increased. Have your write-up ready for Monday, as well as your buoyancy problems to review before we move on to fluid pressure.

F Block reviewed their buoyant forces lab and the associated lab questions and then, after reviewing the buoyancy homework, moved onto fluid pressure. Fluids exert pressure on objects in them and on their containers. For a closed system, if additional pressure is added to the system, it is transmitted equally in all directions in the fluid - Pascal's Principle. We discussed how this applied to hydraulic devices and worked a few problems in class with a hydraulics device. You have a few more to work for homework and we'll go over these on Monday before moving on to looking at how fluid pressure varies with position in a fluid column.

Have a great weekend!

Name the Book

Another +10 geek points if you know the book... Take a further +10 if you've read it...

Now, We're All Soaked

On top if the torrential rain that started the day, all groups now are working through the fluids unit.  B and E Blocks had a discussion about buoyancy and how to experimentally and mathematically determine the magnitude of buoyant forces.  Tomorrow, E Block will work in a lab that will let them take a closer look at buoyant forces and preview a few ideas about the effects of depth or altitude on forces and pressure.  B block will begin their study of fluid pressure with a look at Pascal's principle and hydraulics.

B Block discussed fluid pressure in class and looked at some techniques for solving problems involving simple hydraulic devices.  Tomorrow, we  look at how depth or altitude influences the pressures objects experience.  E Block worked on their lab on buoyant forces and investigated how sending a object deeper into a fluid affected the size of the upward force acting on the bottom of the object.  By graphing the force on the object versus depth, we were able to determine the density of the fluid in which the object was submerged.  We'll review this lab tomorrow, go over your homework problems for buoyancy and then move into the arena of fluid  pressure.

Facing Fluids

B and E Blocks worked on their rotational dynamics and equilibrium exams today, while C and F Blocks began their work on fluid mechanics. Liquids and gases have their own characteristic interactions with forces and we started with the idea of buoyant forces. Fluids exert upward-directed forces on objects you place in or on them and the resulting change in the object's motion depends on the net force the object experiences (the difference between its weight and the buoyant force). We looked, experimentally and Archimedes Principle, then took the easier method for determining buoyant force : F_B = ρ_fVg. Remember that volume of the displaced fluid is equal to the object's volume. We'll go over your practice problems tomorrow (B Block) or Friday (F Block) and tomorrow will find F Block conducting a laboratory investigation on Archimedes Principle.

Statisticians... and Scientists

In Transition

C and F Blocks endured their rotational dynamics and equilibrium exams today and will jump into the deep pool of forces in fluids tomorrow. B and E Blocks engaged in further review for their exams, which will fall tomorrow. Catch up with me before school if you have any questions.

Conservation of Angular Momentum

Here's a couple of videos to watch to highlight a few examples of conservation of angular momentum. For the merry-go-round video, pay attention to how much mass is located at the edge of the merry-go-round and what happens to the angular speed when the mass becomes more closely distributed around the axis of rotation. You see the same ideas in the second video, adding in the vector nature of momentum (which we didn't cover in class, but is fun to see anyway).

Rolling to a Stop

B and E Blocks got a reprieve for tomorrow's exam. We'll have the exam on Wednesday and use tomorrow for general review (E Block) and general review/lever and pulley lab discussion (B Block). For C and F Blocks - the governor did not call. Tomorrow is still the day for your rotational dynamics and equilibrium exam and today was spent reviewing material for that experience. If you need help, email me tonight or stop by my room tomorrow morning before school and we'll see what we can do. On Wednesday you guys move on to forces in fluids, starting with a look at fluid pressure.

Quote of the Day

"Chickens are too stupid to mutiny."

from MST3K's riff on Prince of Space. Catch the video if you want a laugh...

Friday is Fun Day!

B Block went over their simple machine homework and then reviewed for Tuesday's exam. On Monday, you'll work on a lab that investigates levers and pulleys that will let you wok with the concepts of mechanical advantage and efficiency.  C Block conducted that lab today and found that distance is the key to multiplying your effort force.  Apply a force through a large distance and you use a relatively small force to get a job done.  F Block conducted only the lever potion o that lab today, but e main concepts were still emphasized (albeit without the fun of working with pulleys and pulley systems).  Poo old' E Block spent the period getting some problem-solving practice for Newton's Second Law for rotation, conservation of angular momentum and conservation of energy.  I'll get some videos up this weekend to give you some additional guidance, but feel free to email me if you have a question.

See folks Monday!

Simple Machines

Everyone was in the kingdom of simple machines today. The nature and purpose of machines was discussed, as was the tradeoff between force and distance that is a known consequence of using a machine. The other known cost of using a machine is the loss of useful energy/work, which is assessed by the machine's efficiency. Make sure you can differentiate between ideal mechanical advantage (IMA) and actual mechanical advantage (AMA) and explain why IMA>AMA for real machines. Tomorrow, C Block will work on a lab centered on levers and pulleys and F Block will take on just the lever portion for a short-block activity. B Block will be reviewing for Tuesday's exam, performing the levers and pulleys investigation on Monday, and E Block will get some problem-solving practice for conservation of angular momentum and mechanical energy.