Hard Definition and 1000 Threads

OK, this is really confusing me. Mostly because i suck at spatial stuff. If the gradient vector at a given point points in the direction in which a function is increasing, then how can it be perpendicular to the tangent plane at that point? If it's perpendicular to the tangent plane...

physics! Science! Really Hard how does friction affect how far an object will roll

Homework Statement so a block of mass m slides on a frictionless surface of an inclined plane of angle theta which itself has mass M and can slide on a horizontal surface. Assuming no friction, find the accel of the block and the inclined plane.. The Attempt at a Solution well...

I am a mechanical engineer currently working in design at a semiconductor/data-storage process equipment company. I've come to learn that I am better at analysis than i am at design. I like using and gathering data and developing specifications, whereas mechanical design requires a kind of...

Homework Statement hi there, I am having some trouble with my physics homework and i was wondering if anyone can help me. i have no clue what to do. these are the questions 1. what does the slope of the graph "maximum force of static friction vs normal force" mean? (maximum force of...

Very Hard Projectile Motion making me nuts<Help, Urgent!> Hey there, i am in grade 12 4u physics course and i would really appreciate it if someone can help me out with the following Projectile Motion questions. I tried to figure out how to do it but i can't think of any. Question:1...

If G is a connected graph with a cut-vertex v and G1 is a component of G-v, then show that the induced subgraph <V(G1)U{v}> of G need NOT be a block of G. I guess all I would need is a counterexample, but I can't come up with one.

Homework Statement a pendulum of mass m and length L is pulled back an angle θ and released. After the pendulum swings through its lowest point, it encounters a peg α degrees out and r meters from the top of the string. The mass swings up about the peg until the string becomes slack with the...

Homework Statement ((e^{iz})/((1+z²))) Find a Laurent expansion valid for 0<|z-i|<1and use it to show that the derivative will leave you with the residue a₋₁. So we have an annulus with its center at one of the singularities. Since the other singularity at z=-i is outside...

Hard Kinematics Question- Please Help! Homework Statement When placing traffic lights at an intersections, planners have to determine how long the yellow light should stay on. This will depend on the speed limit on the road and on the length of the intersection. Outside a building,on the...

Hi all, A friend of mine asked me if i had any ideas about the following problem, i tackled it but with no success, so i thought i would post it here. It is not a homework problem, or a regular textbook problem. Problem: If we know that a series with positive terms ...

I am designing a component (Cam Driver) that has 2 features. One feature that acts as a cam, it slides against another component with heavy surface stress to move the other component. The 2nd feature of this Cam Driver is a threaded rod that mates with a piston in a pneumatic cylinder, thus...

The last time I defragged a hard drive was on my desktop computer with windows vista. My laptop seems to be slowing down slightly, I was hoping to defrag it, as it has not been for a very long time. I don't know where to go to access this feature in windows XP. I use "search" in the start bar...

1. How can something travel faster than light? 2. You have two identical bars of iron – except that one is a magnet. Without using any piece of apparatus, or any other object, how can you find out which is which? Hope you can help Thankyou :)

Homework Statement Does there exist a continuous function f: R -> R such that f'(f(x)) = x ? Homework Equations The Attempt at a Solution I was trying to find an example, but wasn't able to, and if I had to take a guess whether such a function exists or not, I'd say no. Here...

Homework Statement Help, I don't know how to do the following question: Using Laplace to solve x' -y =1 2x' +x +y' = (t2-2t+1)e-(t-1) Homework Equations x(1)=0 y(3)=0 The Attempt at a Solution The problem I'm having is the initial conditions aren't at zero, and I'm not sure...

How would you integrate this. I tried all integration methods available in Calculus II to no avail. ∫√(1+sin x) dx

Homework Statement A ball player hits a home run, and the baseball just clears a wall 8.00 m high located 122.5 m from home plate. The ball is hit at an angle of 39.9◦ to the horizontal, and air resistance is negligible. Assume the ball is hit at a height of 1.2 m above the ground...

Homework Statement Prove that sin(5A)+sin(2A)-sin(A) = sin(2A)*(2*cos(3A)+1)Homework Equations sin(2A) = 2(sin(A)cos(A)) cos(2B) = cos2(A)-sin2(A) cos(A+B) = cos(A)cos(B) - sin(A)sin(B) sin(A+B) = sin(A)cos(B) + sin(B)cos(A) The Attempt at a Solution I can't find any other way than to just...

Inspired by the recent thread on flying coffee grains I felt the urge to ask if anyone knows why coffee is so darn hard to clean up? It doesn't stick to the rag as most substances do. I'm assuming it has something to do with the grains' surface structure, but what kind of physics describes this?

Homework Statement "Demonstrate that in the limit (nu)---> 2w0 the solution to the damped harmonic oscillator equation becomes x(t) = (x0 + [v0 +(nu/2)x0]t)e^(-(nu)t/2)Homework Equations Solution to damped harmonic oscillator equation; x(t) = a*e^(-(nu)t/2)cos(w1t - (theta)) Where a = [x0^2...

A long time ago, I was once told that too much reliance on databases in programing can create slow programs. Databases provide a nice way to store and organize information but they may not retrieve and write information quickly. Clearly ram is the fastest way to access meomry but the size of ram...

I can't find a solution to these questions. Can someone help? 1. An algorithm to determine if a Sudoku puzzle is easy, medium, hard, or evil. 2. For every valid Sudoku puzzle, there exist at least one valid solution. True or false? Proof?

I recently bought 2 - 1 tb external hard drives from tiger direct. http://www.newegg.com/Product/Product.aspx?Item=N82E16822111019 My computer and other computers I have tried them on will not recognize them both plugged in together. it only recognizes the one i plug in first then when i...

The picture speaks for itself, can anyone explain to me how to do this, they put it near the start of my book and i keep coming back to it yet no sine or cosine formulae etc... can help, please :)

Homework Statement Let A and B be sets and let f: A \rightarrow B be a function. Define a function h: \mathcal{P} (B) \rightarrow \mathcal{P} (A) by declaring that for Y \in\mathcal{P} (B), h(Y)= \{ x \in A: f(x) \notin Y \}. Show that if f is a bijection then h is a bijection. The...

basically, my opinion is that STEM careers are enjoyable BUT intellectually a lot toughter than other careers. It's been theorized that the reason why less Americans (and more foreigners) major in STEM is because kids who grew up in America do not want to work very hard (a product of...

I am currently a student taking a break from school. Last year I had a major life altering experience and after which i decided to take a break from my studies till my mind was settled. When I started my undergraduate track I went to a tech school in NY and had decided on studying software...

I saw a post on this forum from a few years ago ('07) asking the same question, but I thought it might be good to ask it again: Is anyone here a gay physicist, chemist, etc. in the hard sciences? It'd be nice to have someone to chat with online that's in the same situation, since it is...

Homework Statement In Fig. 13-41, a particle of mass m1 = 0.23 kg is a distance d = 84 cm from one end of a uniform rod with length L = 6.4 m and mass M = 2.4 kg. What is the magnitude of the gravitational force on the particle from the rod?Homework Equations...

I was accepted to an electronic engineering course as a mature but I only put that course on the list for the sake of putting a few courses down. The real course I want to get into is chemistry but I did a bad interview for that course and I got accepted into electronic engineering instead. The...

Greetings, As I am in vacation now there is no way to ask my teacher so I will resort to this forum, I searched and didn't find it on the forum ( hope I haven't skipped anything ) so here goes my question: For the Runge-Kutta integration methods, I am really puzzled as to what the 'f'...

I'm taking the class next semester, and I heard that number theory is usually a difficult subject. Is that true? If so, how should I approach it?

I have a laptop at at the moment but I'm afraid that I chose the wrong one. Its a 16in, 7.1lb monster with a battery life of a measly 2.5hr max. I could upgrade the battery but it would add over a pound in weight and make it even bulkier though. I'm thinking about returning it (if I can) and...

Hello all, I'm new here to the forum. My name is Chris and my one "burning" question is that do you think that being hard of hearing will be a major obstacle for me to pursue in this field for a career? I know that the military still refuse to hire any of us but I'm wondering in the other...

I would like to know how to "defrag" a hard drive, and what the gains are to doing so. I am using windows vista home premium 64-bit with a single hard disk installed into my computer. Where do I go to defrag my drive? How long does this take? Are there any potential risks of causing data damage...

tractive motion, with gradients, Hard questions! 4.1 An engine mass of 95 tonnes is hauling a train of mass 750 tonnes along a section of level track. the tractive resistance to motion of the engine is 120 N/tonne and the rolling resistance for the train is 90 N/tonne. initially the engine is...

Really hard intergration problem\! take a look A 20-lb. monkey is attached to a 50-ft. chain that weighs 0.5 lb. per (linear) foot. The other end of the chain is attached to the 40-ft.-high ceiling of the monkey's cage. Find the amount of work the monkey does in climbing up her chain to...

Hard intergration problem! 1. A 20-lb. monkey is attached to a 50-ft. chain that weighs 0.5 lb. per (linear) foot. The other end of the chain is attached to the 40-ft.-high ceiling of the monkey's cage. Find the amount of work the monkey does in climbing up her chain to the ceiling...

Compound gear train problem (WHY IS IT SO HARD!) Homework Statement http://img5.imageshack.us/img5/1663/problemw.jpg I need to calculate the angular acceleration of the fan at 2600 RPM (motor speed) depicted by figure 4. Homework Equations Sum(torques with respect to input) =...

Homework Statement Two objects are placed in a 1 dimensional box with springs of different constants at each end of the box. The box is made of wood and has a length of L. The first object has a mass of M and is initially compressed a distance of xinitial onto spring 1 of spring constant k...

I posted this on another thread but no one has responded. It is truly a great puzzle to work out. So, I am posting it again in its own thread. Enjoy. The "Hardest Logical Puzzle Ever": Three gods, A, B, and C, are called True, False, and Random (in some order you do not know.) True...

Calculating spring equilibrium length HW question... HARD! Homework Statement A spring is connected to the bottom of a ramp inclined at an angle of 45 degrees. In its equilibrium position, the spring is equal to the length of the ramp, L. If the spring constant is 500 N/m and I want to launch...

I'm going to be doing a little venting in this thread so if you don't want to hear about it, click the back button. I'm in my second year of school right now. I'm in Physics 2 which is just basic calc based physics (second semester). I am in awe at how hard this class is. I'm sure most of...

Homework Statement A hawk flying at 2 m/s at an altitude of 80 m accidentally drops its prey. The parabolic trajectory of the falling prey is described by the equation below until it hits the ground, where y is its height above the ground and x is its horizontal distance traveled in meters...

I need to replace my hard drive. The recommendation is: ATA/100 5400 RPM 9.5mm. I see a lot of faster drive 7200rpm but they are SATA. Is it true I can put this in also because they connector should be compatable. I just need to get 9.5mm or smaller and it would be fine? What is the...

Is chemical engineering ridiculously hard? If i really enjoy chemistry would chem engineering be a good choice?

Or at least... that's how it seems... I'm an Astronomy Major. In the summer, I'm all 'I can't wait to study x y and z!' and then two weeks into the semester, I'm just, 'meh. My homework can burn in hell' Completely unmotivated and don't know my future outlook. I pass my courses with average...

Homework Statement The only force acting on a 2 kg object moving along the x-axis is shown. If the velocity Vx is 2 m/s at t=0, what is the velociity at t=4 s ? Homework Equations P= mv The Attempt at a Solution Area under the curve is the Impulse, which is Pf - Pi and it's equal...

Hello All, Well to make the Story short, I made a little bet in school that I could solve all the number sequences on a site, but now's the joke. I can't Ye ye , stop laughing But really I can handle myself at numbers normally pretty well, but this seems out of my league Can anyone solve...