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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!

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

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

I've got a math task to do. Pic related: u can see the task. Which function would you see as the most appropriate? How would you justify such choice. I just don't want to run trough every possible option,. Hope you have any ideas - I've got deadline for Monday.

Would this be the board to discuss the physics aspects (Multiple worlds theory, microsingularities, etc) of John Titor's 2000-2001 little schpeal?

This area of research is starting to get mild popularity. I, for one, cannot seem to grasp how it would work given problems with transfection of a dense tumor in vivo. Why is this being given so much attention given that basic problem. Why not just go back to the work of "tumor immunization" and let the immune system combat the cancers. mfw RNA cancer treatment clinical trials

Most effective way to study Discus

Serious question. Would wood make up for a good space ship material? Suppose you were an advanced species with all the knowledge necessary to make interstellar vehicles, but only had wood at your disposal. Would it work? If not, why?

Check the boxes beside the statements that are TRUE, regarding force and motion. Select all that are True. 1 If an object's speed does not change, no net force is acting on the object. 2 In order to not slow down, an object moving at a constant velocity needs a small net force applied. 3 If two different objects are under the influence of equal forces, they will have equal accelerations. 4 The net force acting on an object that maintains a constant velocity is zero. 5 The net force acting on an object that remains at rest is zero. 6 If a net force acts on an object, the object's velocity will change. Review Newton's First and Second Laws and the definition of acceleration.

Any hints for question (a)? Cannot even see where to start.

Ok /sci/ I've been thinking about relativity for a little while now - time dilation mostly. I have this idea that has helped me understand it pretty well and thought I should run it by all of you to get ideas. I figured since velocity = length(distance) / time then time must equal length / velocity. So when your velocity drastically increases (approaches c, the speed of light), you traverse more curvatures of space-time resulting in less distance (from point a to point b) than say in relation to a more linear, slow moving clock. The length dilation would cause a much smaller L relative to the increase in V in the t=L/V equation, resulting in a lower value for T. Does this make any sense!?

I'm just a noob here, but I think it would be cool if we had this too Make strong AI, together

Hey, guys, what if we took 55 Great Pyramids and stacked them into one huge pyramid? And there would be skyscrapers hanging like grapes inside of it. And let's build it in the sea near a major fault line while we are at it. Would you live in such a thing?

Sorry for bothering you, /sci/, but I need to find out how bright an LED is in lumens. For some reason osram decided to list radiant power instead of lm/W for monochrome leds, and I'm struggling with conversion. Wiki lists that ideal monochromatic source at 555nm is 683 lm/W, but this one is dominant 645nm and I have no idea how to obtain a corresponding number. Using 683 lm/W I'd get 327 lm/W for this LED and it's impossible, afaik there is no such efficient LED. That would be nice though. Here is a data sheet. http://catalog.osram-os.com/catalogue/catalogue.do;jsessionid=5D2E13032790AE07946C5B904F7BE7FB?act=downloadFile&favOid=0200000400023f51000100b6

I've got a question that probably 95% of you can answer. When are you supposed to reduce the subscripts when writing chemical formulas from written names? Apparently Cobalt (II) Oxide > CoO But Tetrasulfur tetranitride > S_4N_4

If you roll a 20-sided die 20 times, what are the odds that you get a 20 at least once? My terrible long-since-used math knowledge tells me that the answer is 5 (as in 5%) times 20 equals 100, but it's not guaranteed to happen, obviously.

I was staring at this picture when dad walked past my room, he walked in and asked who these people are. I pointed to Einstein and Curie and said you should know who these two are, he said yes. I then pointed to Planck, Bohr, Lorentz, Schrondinger and Heisenberg and asked again, he said he had no idea. He asked about what they contributed to science, I told him about quantum entanglement (which he had never heard of before), I told him about the constant debates between Einsten and Bohr about determinism and a probabilistic view of the universe, I also told him about quantum superposition. He asked about what quantum entanglement proves, I told him that it could be used for long distance communication, possibly even teleportation. He just nodded and said, good. Then walked off. Did I ruin my chance to explain science to a deepy religious man or was I right when I said entanglement can be used for communication with 0 time delay

>When you see it, you'll rage

Hi /sci/ Can you recommend me a short but good tutorial to learn Waves and Optics? I have an exam in 24 hours and need to get prepared as fast as possible. I'm aware that I'll probably fail, but I want to try as hard as I can not to. Any help?

I need help pls! A block of an alloy of mass 39.0 g and at a temperature of 9.32 °C is placed in a calorimeter containing 42.0 g of ethylene glycol at 90.32 °C. If the final temperature of the alloy and ethylene glycol is 59.38 °C, calculate the specific heat (in J/g/K) of the metal. The specific heat of ethylene glycol is 2.39 J/g/K. Express your answer to three significant figures in scientific notation.