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Got a physics I problem I'd like some help with if anyone is up for helping a brother out. Just guidance is more than sufficient. It seems like a basic circular motion problem, but I missed the lecture on it when my professor taught it in class. Here's the problem: The angular velocity of a process control motor is w = (20 - .5*t^2) rad/s, where t is in seconds. a. What time does the motor reverse direction? b. Through what angle does the motor turn between t = 0 s and the instant at which it reverses direction? So here's my thought process on this one. For part a), set w (the angular velocity) to 0 to solve for t (where I'm guessing is the point that the motor changes direction). So 0 = 20 - .5*t^2 >> t = sqrt(40) s. For part b), take the derivative of the equation to get the angular acceleration, plug it into Af = Ao + wi*t + .5(alpha)*t^2 to get the answer in radians, then convert to degrees if I want to. I ended up getting -20.13 degrees for my final answer, or 125.49 rads. This question doesn't exist on any website (trust me, I've tried looking) so there is no way I can check my answer (not in the back of my textbook). Any guidance AT ALL will be most appreciated!

What is the pattern: 3, 9, 25, 65, 161... God mode: No Wolfram.

I am a geometry teacher at an urban high school currently on the subject of trig. just focusing on sine, cosine, and tangent with law of sies/cosines thrown in (thats the curriculum). Now this is supposedly the city's STEM themed academy, but I think the decision for many of these students was 100% parent based (even though there is almost no parent involvement in the school) so I am trying to think of something interesting to show the kids so they will perhaps care enough to actually study. Of course I am just a shitty math teacher, so I am hoping for some help from sci tl;dr shitty geometry teacher looking for something interesting to show his students regardeing trig. can be something above the basics if I can point in the general direction to how we would get there.

Consider the matrix with rows [1 3 2 1 0], [0 2 -1 0 -1], [2 1 -5 0 0] with c = [3 2 5 0 0] and solution b = [15, 5, 10]. Suppose that the list of basic variables consists of x4, x2, and x1 in this order. Present a simplex tableau corresponding to this information. Determine what the solution is at this stage and if it is optimal. Any help would be greatly appreciated.

How do /sci/entists feel about people who throw away a lot of money to earn a degree in "tourism studies" or pretty much any non-STEM major?

We had technical difficulties yesterday with the thread so I made some overall changes to the overall layout and I believe now it is fixed :) We now have control of Gnuspace.org (not up yet), as well as Gnuspace.com I believe Vegnagon bought that one.. Because this mission is so hard I propose to divide the workload into steps. Step 1 consists in making the robot create it's own power source. It will use solar power only at the beginning because any other source will be orders of magnitude harder to accomplish and more expensive. Question: How large and how heavy do you believe the first robot would be if it had the capability to swallow soil and reject inter-connected solar panels behind it. This would be similar to “Living on the moon” concept but at a much smaller scale because we are constrained by weight. If we get a launch it will have to be funded with crowd-sourcing such as kickstarter and it probably won't cost more than $100,000 (very easily achievable on Kickstarter). I would like to add none of any money raised will pay people working on the project. Only materials will be bought. Work will be volunteered, so as to respect the open-source spirit and avoid corporate or governmental control.

Hey guys, need some help with this: Hemispherical bowl (don't question it), with radius of 10cm. Bowl is filled with water, such that the surface of the water has a radius of 7cm. Use Pythagoras to find the depth of the water. Please give as much detail/working as you can. Thanks

Yo /sci/, Can someone show me how to work this out please? 10. A sample of fluorine-17 is decaying at the rate of 2.5 x 106 atoms per second. After a further 5 ½ minutes, theactivity has fallen to 3.9 x 104Bq. calculate the half-life of fluorine-17. pic unrelated.

Just found out about the secret of "Pi" Add time to the equation, start from the begining, use plank time, and you will be able to see the past present and future.

What do you guys think about this guy's theory: http://en.wikipedia.org/wiki/Egyptian_pyramid_construction_techniques#Jean-Pierre_Houdin.27s_.22internal_ramp.22_hypothesis http://www.youtube.com/watch?v=ZLxJY91Cv0o

Sci can you help me with some general biology questions on cellular osmosis? yes i know i am not that smart 1. Explain what happens to a cell, in terms of osmosis (not just ordinary diffusion), if it is immersed in a solution which has a greater concentration of solute particles (hypertonic) than that inside the cell. (Assume water is the solvent) 2. Explain what happens to a cell in terms of osmosis if it is immersed in a solution which has a concentration of solute particles that is the same (isotonic) as inside the cell. 3. Explain what happens to a cell, in terms of osmosis, if it is immersed in a solution which has a lesser concentration of solute particles (hypotonic) 4. Name and explain at least two mechanisms or adaptations by which a cell can regulate possible harmful effects due to adverse osmotic conditions. a. b. 5. Name and explain two instances in which the effects of changes in osmotic pressure are seen in everyday life (not necessarily in a biology laboratory) a. b. ?

>If some men are doctors. And some doctors are tall. Does it logically follow that some men are tall?

I need your nerdy expertise, /sci/ Have you heard of a course called Phenomenal Memory? It's founder claims that his memorization methods allow one to create a "database" in one's head, using a combination of the memory palace and several sorts of mnemonic techniques, encoding information into images in a formal, rigorous manner. the link is http://www.pmemory.com/ And here is the torrent, just to make it clear that I'm NOT in any way advertising for this guy. I'm genuinely curious as to what you guys think. http://pirateshit.com/torrent/6334613/School_of_Phenomenal_Memory Maybe there are other, better methods of memorization?

Guys i need some help on this problem, it's not homework, i just want to know if i'm doing this right. Basically, i have this sequence of functions: f_{n}(x) = \frac{n(1 + x)^2 - 2x^2}{nx(1 + x)^2} First of all i have to find the punctual limit of this, and it's pretty easy to find that it's \frac{1}{x} Next thing i have to do is determine if the series \sum_{n = 1}^{\infty}f_{n}(x) converges in some point of \mathbb{R} - \left \{ 0,-1 \right \} Now, it is true that a series of functions, like a series of numbers, doesn't converge if the general term f_{n}(x) doesn't go to 0 when n goes to infinity. In this case, as f_{n}(x) \rightarrow \frac{1}{x} as n goes to infinity, does this mean that the series cannot converge in any point as 1/x is never 0?

How much did you spend on textbooks this year? So sick of being jewed. Even when bookswapping I get jewed by randoms. Why do books cost $180?

Can anyone help me with this babby's first statistics/probability problems? I tried applying the rules but I'm not really sure how to solve it. 1) The probability of making zero to two errors per 1,000 keystrokes is 0.51 and the probability of making three to five errors per 1,000 keystrokes is 0,24, Find the probabilities (per 1000 keystrokes) associated with each of the following. a) at most two errors b) at least three errors c) at most 5 errors d) more than 5 errors

random forest. am i re-sampling attributes only at the root, or for each node?

Hey sci, I need some help and I think you're the only place that can help me. I have a problem that is asking me to find the capacitance of a capacitor given a certain area, material and distance. I calculated that fine. But after that it wants me to calculate the maximum voltage allowed on the capacitor given a dielectric strength of 12V/m. So to recap: dielectric constant of 6.7 7.2cm^2 area on plate and separated by 470 µm All of that comes out to 90.88pF But I can't for the life of me figure out how to get the other part. Help please?

Lest say i need the earth destroyed or at least uninhabitable by any form of life, i need it done in a year and i have all the resources in the world, how do i do it?

Popular science.... i know /sci/ doesn't like those groups like 'i fucking love sience', and indeed, they are horrible. But what about this guy? http://www.ted.com/talks/tyler_dewitt_hey_science_teachers_make_it_fun.html Does sience needs to be fun? For highschool student, it might be better? Also, what do you guys about that other new trend? Those youtube-guys who explain science on a very low level? Scishow, crashcourse, brainscope, asapscience, minute physics... to name a few?