LAST WEEK

Mon– Discuss Week ahead, AOW, BOW, Slide Show, JM, Discuss lab & graph & relationships ; Soph/Jr PSAT Prep Session (6:30 – 8:30PM) (English)

Tues– Discuss Divisions, especially Rocketry, Freshman PSAT Prep Session (6:30-7:30PM) (Math)

Wed – HO 2.8 Unit Analysis III; ; HO Packet 2 Take Home Test; Go over Modern Physics History; Spent the hour talking about the negative TRIO and all the cool stuff that it represents, EVENING: Freshman PSAT Prep Session (6:30-7:30PM) (English)

Thur–HO 2.9 What is the Slope of that Curve? Discussed Escape velocities; discussed gravity wells; discussed alien races and whether we could whoop them in hand to hand combat; Discussed how weird acceleration can be; Packet 2 Reading Answers due by 4:30PM; Discuss 2.9; EVENING: Soph/Jr PSAT Prep Session (6:30-8:30PM) (English)

Fri–Finished coloring in the Stegosaurus tail and showed how it could be used to determine the changing slope of the curve. HO 2.10. Went outside and “chased the mouse” to help us determine the trio. Rocketry applications are due by 4:30PM. Wrote down our data from the 9 meter ramp. Played volleyball outside for the last 15 minutes.

THIS WEEK (my best guess)

Mon – TRIBE DAY. You must have 2 sides of the Take Home Test #2 done.

Tues – RED DAY for THT2

Wed- Wrap up day. We will spend quite a bit of the time on 2.10 and will fill in as many other gaps as possible.

Thurs- 100pt Notebook due; 100pt Packet 2 due, 36pt Division Check; 200pt Test 2

Fri – You deserve a Feast and Film ! — Bring all those goodies.

: Physics Fall 2014, Packet 2: Volleyball has A LOT of physics. Projectile motion and Newton’s 2nd and COn of Mom everywhere! Here coach tortures her players by firing endless volleyballs at their diving bodies.

: Physics Fall 2014, Packet 2: How many of these characteristics do you possess?

: Physics Fall 2014, Packet 2: Good place for lunch.

: Physics Fall 2014, Packet 2: Here pacman is your only friend.

: Physics Fall 2014, Packet 2: Here is how the History section of the test will be scored.

: Physics Fall 2014, Packet 2: These graphs represent about 75% of your linear motion for the day.

: Physics Fall 2014, Packet 2: One of the most important equations in history. Galileo unlocked the relationship between change in position and time when gravity is the force involved. It helped him understand a little more about gravity. Who knows how far he would have gone if he had stayed with this exploration . . . could he have invented a form of calculus? Probably wasn’t a good enough mathematician. Instead, the Danes send him some lenses and that caught his attention and changed the world of astronomy.

: Physics Fall 2014, Packet 2: Instead of using the fish (“is proportional to”) , we use a k (a proportionality constant) so we can use an equals sign.

: Physics Fall 2014, Packet 2: A proportionality constant is a lower case k (not cursive). Physicists are very particular about their letters.

: Physics Fall 2014, Packet 2: This is the graph of the ball rolling up the incline and back down. This is assuming pacman (friction) is very minimal. Check it out! The perfect bow tie! The yellow part represents the ball going up the incline and the brown part represents the ball going back down the incline. The apex is where the ball turns around at the top. Notice the ball’s velocity is temporarily zero there.

: Physics Fall 2014, Packet 2: So the area of the yellow triangle tells you how far up the incline the ball went. The area of the brown triangle tells you how far back down the incline the ball went.

: Physics Fall 2014, Packet 2: The slope of the v vs. t graph tells you how quickly the ball was slowing down on the way up and how fast it was speeding up on the way down. We call this slope the acceleration of the ball. It is negative the whole way!! You mean it is negative and it is making the ball speed up on the second half of the balls journey. How is this possible. How can negative acceleration make a ball speed up? Think about it! Hint: we established that “up the incline” was the positive direction.

: Physics Fall 2014, Packet 2: This is cool! We figured out that you could determine the initial velocity of the ball up the incline by using the info on the graph. It’s like magic! The area of the triangle is 1/2 b h. The h is the initial velocity.

: Physics Fall 2014, Packet 2: This is what I was talking about on the previous slide.

: Physics Fall 2014, Packet 2: It is weird that the units of area in this case is cm, not cm squared.

: Physics Fall 2014, Packet 2: When we did Slappy the Clown, it was a duet. It was a piecewise function. but the velocity is zero order (meaning that the exponet on the t is zero), the position vs. time is 1st order (the exponent on the t is 1) .

: Physics Fall 2014, Packet 2: A look at a true trio. 2nd order on top (x vs. t); 1st order below that (v vs. t); zero order below that (a vs. t)

: Physics Fall 2014, Packet 2: More on the trio.

: Physics Fall 2014, Packet 2: Bill displays his latest work. I believe he said it was a binary counter.

: Physics Fall 2014, Packet 2: Know this graph for the test. A bunch of different scenarios involving v and t. Remember if the slope is positive, acceleration is positive no matter how weird it seems. If the slope is negative, acceleration is negative.

: Physics Fall 2014, Packet 2: Escape velocity for the earth is our first constant.

: Physics Fall 2014, Packet 2: this is showing how an acceleration vector in the opposite direction as the velocity vectors for an object slows the object down.

: Physics Fall 2014, Packet 2: here is the same idea as the last slide. This time the acceleration is the gentle tug of gravity. If you shoot something up in the air gravity will always have a downward gentle tug until the object turns around and comes back home. Isn’t that nice and reassuring? The Earth doesn’t want us to leave. Actually, anything with mass attracts anything else with mass. I guess all the mass (frozen energy) was together at the beginning of time and ever since the Big Bang has been trying to bring us all back together. It’s that evil dark energy that is trying to pull us all apart.

: Physics Fall 2014, Packet 2: So gravity is approximately 10m/s/s. We will study this later in much more detail, but I thought I would go ahead and quantify it earlier in the year than normal since many of you know it already. That’s a gentle tug, but it’s enough to keep me from dunking the basketball.

: Physics Fall 2014, Packet 2: This is a 2 dimensional view of a 3D situation. We will look at 3D drawings later. The earth is in a pretty big gravity well. Good luck escaping my friend. 11.2 km/s is like getting from NHS to the Warren Theater in about 1 sec except that you are moving straight up (ignoring air drag)

: Physics Fall 2014, Packet 2:

: Physics Fall 2014, Packet 2: Assumptions we have to make for escape velocity to work.

: Physics Fall 2014, Packet 2: When you are moving REALLY fast in our atmosphere (like Mach 0.5 or faster), the air molecules (mostly nitrogen and oxygen) can’t get out of the way fast enough and start to pile up. When you compress air quickly it gets VERY hot (then when you expand it again it cools down . . . ah . . . THAT’S why your central air conditioning has an outside compressor unit!) It also gets really dense and acts as a natural barrier to speeding up which causes exponetially growing air drag as you speed up.

: Physics Fall 2014, Packet 2: . . .

: Physics Fall 2014, Packet 2: The girls sitting at table 7 are tired of cleaning up after the slobs who sit there at lunch. PLEASE clean up your mess. The Cantina can’t afford a maid.

: Physics Fall 2014, Packet 2: The secant is a poor representation of the slope of a curve, but it is a start.

: Physics Fall 2014, Packet 2: So we cut the big secant into 9 equal small secants

: Physics Fall 2014, Packet 2: that looks like profanity to me. Hey, that would make a great tat!

: Physics Fall 2014, Packet 2: Maybe you get this, maybe you don’t. If you do . . . GREAT! Consider a study of Physics in college. If you don’t, never fear . . . we will talk more about it in Packet 3.

: Physics Fall 2014, Packet 2: Matt said . . . “I thought tangents and secants were for circles.” Ah . . . correct young padawan, but isn’t a curve just an unfinished circle? The red line above is a secant. The green are tangent lines. Notice that the middle (timewise) tangent line is parallel to the secant line. This is very important.

: Physics Fall 2014, Packet 2: Remember this from your math class? Tangents touch circles in one point. Secants touch circles in two points.

: Physics Fall 2014, Packet 2: Newton realized that if he decreased the ∆t, the secant lines began to resemble more of a curve. I mean . . . heck . . cutting the ∆t in half (the red secants) looks A LOT better than the orange secant line. When I cut that ∆t in half, I get the 4 green secants and when you put those together, it really starts to look like a curve.

: Physics Fall 2014, Packet 2: . . .

: Physics Fall 2014, Packet 2: . . .

: Physics Fall 2014, Packet 2: cm/s/s is the unit of acceleration, but the short cut (lazy) way of writing it is cm/s^2

: Physics Fall 2014, Packet 2: What we did on Friday.

: Physics Fall 2014, Packet 2: Come on into The 807 at lunch and play a little chess. It beats fighting traffic and getting caught speeding by the army of Norman’s finest that surround the school at lunch. Be extra careful with that motorcycle cop by Berry and Main. He is a good hider.

: Physics Fall 2014, Packet 2:

: Physics Fall 2014, Packet 2:

: Physics Fall 2014, Packet 2:

: Physics Fall 2014, Packet 2:

: Physics Fall 2014, Packet 2: THis must be important because Askey keeps talking about it.

: Physics Fall 2014, Packet 2:

: Physics Fall 2014, Packet 2: From 2.9; We did a full trio

: Physics Fall 2014, Packet 2: Notice the V vs. t is a step function, but we can collapse those steps down to one point because of the midpoint (timewise) trick where average equals instantaneous. and the segment (on the v vs. t graph) becomes a point for each given velocity.