Monday, October 25, 2010
Mon-Day 2
The OVERALL error is trying to invent either longer, inefficient, and incorrect ways to solve a physics problem or trying to invent shorter, insufficient ways to solve a physics problem.
Just do the problems EXACTLY as they are solved and explained in class! If there were a better or more fool-proof way to solve these problems, THAT is the way that we'd be doing the problems!
ALWAYS START WITH A PICTURE and then USE THE PICTURE as you label it, and reason through what is going on in the question. As seen in the picture above, you can play around with projectile motion software at this site: http://www.goldenkstar.com/projectile-2d-motion-mechanics-physics-software.htm
In any WRITTEN-response test, you get credit for any answer ONLY IF you show SUFFICIENT work to support your answer. Generally, writing any answer, correct or incorrect, will not get you any credit. It's even worse to write a correct answer with no work shown because that SUGGESTS copying (though I don't get a general indication of that from our upstanding class).
When calculating the angle of launch or crash, you must find the vertical and horizontal components of VELOCITY, not distance! You then label those components as opposite and adjacent to the angle relative to the horizon, respectively. You then take the inverse tan to get the angle.
We did Dynamics 1, problems 3 and 4. Check your work with Blackboard for the answer to 4.
AP Chem - We then derived Graham's Law of Effusion/Diffusion by considering the mathematical formula for KINETIC ENERGY. At a given temperature/average kinetic energy, the greater the molecular mass of a molecule, the slower its average velocity, thus the lower its rate of effusion/diffusion. We then applied the formula to compare the relative rates of effusion of two different gases.
We did a Graham's Law problem in which we determined the molar mass of an unknown gas based on its time to diffuse from a balloon. We then derived the formula for average speed of a gas phase molecule at a particular temperature. We had to do unit analysis (by showing that a Joule is a
kg m^2 s^-2) and tweak the "3" to a "3000" in the formula so that we could still use the NORMAL measurement of molar mass in "grams per mole".
We discussed kinetic molecular theory that explains and predicts the behavior of gases and also can explain how and why gases deviate from ideal behavior.
We then discussed Vanderwaal's modified gas equation that uses experimentally determined correction factors for real gases so that ideal gas law calculations can be accurately applied.
We discussed the meaning of each of the correction factors and their places in the equation.
We discussed kinetic molecular theory that explains and predicts the behavior of gases and also can explain how and why gases deviate from ideal behavior.
We then discussed Vanderwaal's modified gas equation that uses experimentally determined correction factors for real gases so that ideal gas law calculations can be accurately applied.
We discussed the meaning of each of the correction factors and their places in the equation.
# posted by C @ 10:33 AM 
