Askey Physics

All things Physicsy

11/26 – 11/30 (CirMot, Vectors, Free Fall)

Posted on December 1, 2018 by daskey

I will add captions as I get time this weekend:

: PhyFl18 — SS3.1.1 Monday!

: S3.1.2 From our hallway circular – SHM motion exercise

: S3.1.3 Hallway positions

: S3.1.4 Circular vs. Simple Harmonic Motion (SHM)

: S3.1.5 last question on sheet 3.2 A sort of new equation involving period (Tp) and omega

: S3.1.6 TUESDAY!

: S3.1.7 A vector has a head and a tail. Isn’t it cute?

: S3.1.8 We are going to study the gravity force vector a lot.

: S3.1.9 Here is an example of the use of force vectors.

: S3.1.10 Weird things happen when you add up arrows.

: S3.1.11 3 + 4 = 7 maybe . . . 3 + 4 could also equal 5. It all depends on the angle between the vectors.

: S3.1.12 Here 3 + 4 = 6.

: S3.1.13 Here 3 + 4 = 2

: S3.1.15 Here 2 + 3 + 4 = 1

: S3.1.16 Here 2 + 3 + 4 + 5 = 1

: S3.1.18 There are two ways to describe a vector. Here is the proper description of a MAP VIEW.

: S3.1.1 9 Here is the proper and description and it also shows the component description.

: S3.1.20 THis is the proper description of a PROFILE VIEW.

: S3.1.21 I think this one is from the front of sheet 3.3

: S3.1.22 This is from the front of Sheet 3.3

: S3.1.23 We will always take the acute angle. At least until April when we start talking about work and energy.

: S3.1.24 Wednesday!

: S3.1.25 some examples of vectors we use.

: S3.1.26 Know your vectors and scalars

: S3.1.27 Believe it or not, you CAN represent surface area of a sphere with a vector. In fact, Gausses Law (in Electromagnetics) depends on it. BUT . . . you CAN’T Represent volume with a vector since volume is omnidirectional. If we lived in 4 dimensional space, then you maybe COULD represent volume with a vector.

: S3.1.28 You really should watch a couple of videos with Sean Carroll (Cal Tech Physicist) He even has a Podcast you might enjoy. The JRE’s with Carroll are great.

: S3.1.29 Time is like a river. There can be small eddy currents where it goes backwards for a nanosecond or two.

: S3.1.30 . . .

: S3.1.31 Here is Levi’s brilliant interpretation of the progression of time . . . and the second law of thermodynamics.

: S3.1.32 If there is a big crunch the arrow of time will be flipped and time will go backwards. 2nd Law of Thermodynamics will no longer be valid. The thing is, this probably will NOT happen. The universe will likely end in a “heat death” where Dark Energy finally gets its way and everything is separated. Even your quarks. Yea!!

: S3.1.33 THURSDAY!

: S3.1.34 From the Guest Speaker. Email her for a possible $5000 scholarship.

: S3.1.35 Field trips are the best part of Geology/Geophysics

: S3.1.36 SO we spend most of Thursday at the stadium studying the effects of the gravity vector.

: S3.1.37 1st hour

: S3.1.38 2nd hour

: S3.1.39 3rd hour

: S3.1.40 6th hour

: S3.1.41 7th hour. Who’s that old dude? Oh yeah, DeeLee of course!

: S3.1.42 1st hour’s free fall data

: S3.1.43 2nd hour’s free fall data

: S3.1.44 3rd hour’s free fall data

: S3.1.45 6th hour’s free fall data

: S3.1.46 7th hour’s free fall data

: S3.1.47 FRIDAY!

: S3.1.48 Here are all the class average free fall times. The overall average for the little ball was 1.42 seconds. The big ball’s average time was 1.55 sec. The two times should have been the same since all objects fall at the same acceleration. It comes down to reaction time.

: S3.1.49 The percent difference needs to be with 10% in high school to be considered negligible (kind of depends on the experiment). The two times should have been the same, but there is an excuse here, mainly . . . air drag is different on each ball, but my guess is the main culprit was your reaction time.

: S3.1.50 There are A LOT of rules for siggies. I will leave it up Mr. Powell to torture you with those if you take AP Chemistry. We will just go with determining the number of siggies you get from measured values. The first iffy is the last siggy.

: S3.1.51 We had 3 siggies in our ∆y. Whatever digit is the iffy one (the ± one) that is the last siggy. So, three siggies for the height. Three siggies is plenty for high school work. The problem is, how many siggies can wee get out of the time?

: S3.1.52 So remember that our goal was to determine what the acceleration of the balls were due to the gravity force vector. Here is the kinematic equation we will use to determine that acceleration

: S3.1.53 Our over all average time (after over 200 free fall drops) was 1.5 seconds (that’s to two sigs) Time limited us to two sigs. We had three sigs with the height, but that extra sig fig was wasted since the time only had two siggies.

: S3.1.54 Here is a new formula for you. Percent Error is the moment of truth. It tells you how close you are to the accepted values. In this case, the accepted value for acceleration due to earth’s gravity. To two sigs it is 9.8 m/s/s. Our value (when all times from all classes are averaged) is 9.9 m/s/s. That is a ONE PERCENT ERROR. That is the closest that we have come in 30 years. A little luck? maybe. A lot of skill? . . CERTAINLY!

: S3.1.55 Monday we will quantify the human reaction time.

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