Hard Definition and 1000 Threads

calculus(dv/(g-kv^2)) I think it's incalculable. Could anyone approximate it ?

Another hard physics problem?? Homework Statement A spaceship ferrying workers to Moon Base I takes a straight line path from the Earth to the moon, a distance of 384000 km. Suppose it accelerates at an acceleration 19.4 m/s2 for the first time interval 14.4 min of the trip, then travels at...

Homework Statement Calculate the maximum packing fraction of the unit cell volume that can be filled by hard spheres in the Hexagonal structure Relevant eq: Volume of spheres is number of lattice points multiplied with the maximum volume of one sphere. The Attempt at a Solution I...

a really hard one here. would appreciate help on how to do this question: a physical system is governed by the following: curl E = -\frac{\partial B}{\partial t}, div B = 0, curl B = J + \frac{\partial E}{\partial t}, div E = \rho where t = time, and time derivatives commute with \nabla...

Homework Statement http://img238.imageshack.us/img238/3648/hrwfop7echpt2128br6.jpg Homework Equations Coulomb's Law Vector Form: \vec{F}_{12} = \frac{k_{e}q_{1}q_{2}}{{r_{12}}^2}\hat{r}_{21} Scalar Form: \vec{F}_{12} = \frac{k_{e}|q_{1}||q_{2}|}{{r_{12}}^2}...

Homework Statement f is a continues function in [a,b] and has a second derivative in (a,b). L(x) is a line that goes through (a,f(a)) and (b,f(b)). Prove that if f''(x)>0 in (a,b) then L(x)>f(x) for every x in (a,b) Homework Equations MVT The Attempt at a Solution First of...

how can an elementary particle like a photon be massless? How can physicist measure and detect a photon if the don't know its inherent properties? I know a photon travels at the speed of light , but wouldn't you have to know a particle mass , in order to know its speed? Or are physicists...

Momentum Conservation --- so hard! Homework Statement Two automobiles collide at an intersection. One car of mass 1.4 X 10^3 kg is traveling at 45km/h [S]; the other car of mass 1.3 X 10^3 kg is traveling at 39km/h [E]. If the cars have a completely inelastic collision, what is their velocity...

i just can't figure this out. given a n x n matrix (with n>1) "A" such that all entries are integers and A is invertible such that A^{-1} also has integer entries. Let B be another matrix with integer coefficients so that: A+B, A+2B, A+3B, ... A+(n^2)B Are all invertible with integer...

So I use "date modified" as a sort of organizational tool - and would like to keep that. When my NTFS hard drive transfers files to a FAT32 hard drive, date modified attribute of folders is kept. However, I reformatted the FAT32 hard drive into another NTFS hard drive - and the date modified for...

Some diabetic patient's nails become really hard, and then they it's really difficult to cut them. Is there any thing by which your nails can become soft, and easy to cut? Is there any useful pedicure equipment? Thanks in advance!

isnt possible to make cost efficient spacecraft by putting multiple types of rockets on a ship which can then alternate rocket engine at different levels of the atmosphere and eventually escape into space?

hey here is my questions: Find all y satisfying the inequality z<y^2-6/y-1 problem is i do not know where to being, considering there is 2 unknowns. And the top doesn't break down which could simplify the question. Could someone help me out or help me start this question off? thank you.

can someone give me some really hard intergrals to solve? make sure they are in the range of calculus 1-2 (anything before multivariable) My teacher assigned some few hard integrals, and they are fun. I want to try moer. thanks.

Does anyone have a strong hard drive preference? I used to buy only Seagate drives, but I recently had a Seagate drive die and I'm thinking about going with another company this time. What do you guys think about Western Digital or Maxtor?

well atleast i think this problem involves integration. i also duno how to derive this into a formula. ok, so this rocket is taken out to space so there are no external forces acting on it (ie if the rocket moves at 2m/s it will continue to move at that speed FOREVER as there is no other...

My mum told me this one, it's pretty cool :). The red car and the blue car are having a race. The red car, which has a top speed of 70mph has a 20 minute head start over the blue car, which has a top speed of 80mph. Assuming that top speeds are reached the very instant a car starts, and...

Why do some people like sleeping on hard mattresses and others prefer softer ones? And why do humans need matresses and beds at all?

Hello, I just got my midterm back and kind of very disappointed. I am a Grade 12 student taking programming in C++. I am using the C++ for you++ book, which is kind of dry and doesn't explain alot. I took a course in C last year. I was very good at it. Was the top of my rather small class...

Hi all, I'm quite new to posting; just been reading around the forums when I came upon this question for my assignment. I'm really quite stuck and no idea how to relate the different values (such as number of moles of Barium Sulfate) found back to the unknown compound. An unknown compound...

1. If d|ab and gcd(a,b)=1, prove that d=d1d2 where d1|a and d2|b and gcd(d1,d2) = 1 Homework Equations 3. Let d1 = gcd(d,a). Thats all I know

"Simple" part of a hard problem involving momentum/kinetic energy conservation Two balls, of masses mA = 36 g and mB = 64 g are suspended as shown in Figure 7-44. The lighter ball is pulled away to a 60° angle with the vertical and released. (a) What is the velocity of the lighter ball before...

Homework Statement 1 oz of 80% pure (NH4)2SO4, 1 gallon of water @ 25 degrees Celsius. 1 gallon = 3.785 L, 1 oz = 28.4 grams. Suppose an avid gardener prepares a solution by putting 1 oz of 80% pure Ammonium Sulfate in a gallon of water at 25 degrees C. a) what is concentration of...

Hard for me to say "Bye" to you-Tears for Physics I'm a undergraduate student in China,in a un-famous University,studying technology,which is because I didn't get enough marks in the exam of the entrance to university,and rejected by physics school.As you know or not,MARKS is everything in...

Homework Statement Test to see whether the following series converges \sum_{n=1}^\infty \sqrt[n]{2}-1 Homework Equations All we've done so far is integral test, ratio test, and root tests.The Attempt at a Solution As n approaches infinity, the term apporaches 0, so it may or may not...

Homework Statement Two long parallel wires, each with a mass per unit length of 40g/m, are supported in a horizontal plane by 6 cm long strings, as shown in the figure below. Each wire carries the same current I, causing the wires to repel each other so that the angle (theta) between the...

This is from my brother: I'm graduating this May, and I'm still unable to find any job offers. I interviewed with Fujitsu a few weeks ago but they haven't contacted me since. I'm a 4th yr Chemical Engineering major at UC Berkeley, but my GPA's low (2.8) and I haven't done any research or...

Homework Statement if you knew that the acceleration of a body is inversely proportional with square the time from the time interval (t=2'' to t=10''), and at t=2'' its velocity was V=-15 m/sec., and at t=10'' its velocity was V=-0.36 m/sec. if its postion from the origin point at t=2'' is...

Hello everyone :) As I was thinking about the logical outcomes of hard determinism, I found a weird one which states hard determinism is not necessarily true If hard determinism is true, Every single event at present will be due to the past events and all those past events due to the...

Homework Statement Question 20 You are traveling at constant speed in an airtight car with a balloon floating motionless next to you. Suddenly, you slam on the brakes so as to stop the car quickly. During decceleration, with respect to the car the balloon (a) moves forward; (b) remains...

hi guys, I'm not sure if this is the right place for this thread, but i'll do it anyways... I'm currently majoring in electrical engineering and having a hard time with physics... i already finished and don't really have problems when it comes to math like calculus I, II, III, and diffy-q...

not going to lie... this thing got me pretty frustrated. :bugeye: : you're going to need the picture in the link (print it or copy it on a piece of paper, it's pretty easy to draw. http://aycu37.webshots.com/image/10476/2004406912463755374_rs.jpg[FONT="Times New Roman"][SIZE="4"] - The letters...

|1|4|6|9| |D|-|-|-| |S|K|J|A| |Y|U|J|-| |S|G|B|-| |Q|F|J|A| |L|H|U|-| i would love to see anyone break this one i found it on a nothere site that said you could give it away but it took me 5 computer programs that crack encrypted text like that and a few books took me for ever.

A pond of water at 0°C is covered with a layer of ice 4.50 cm thick. If the air temperature stays constant at -11.0°C, how much time does it take for the thickness of the ice to increase to 9.00 cm? Hint: To solve this problem, use the heat conduction equation, dQ/dt = kA delta T/x and...

1. An object (height o) is placed at an object distance S in front of a converging lens. The lens is placed at a distance d<Si (image distance) in front of a very thick glass plate (index of refraction n, thickness larger than image distance). The surface of the glass plate is perpendicular to...

Homework Statement A hemisphere of radius a centered at the origin carriers a total charge Q uniformly distributed over its curved surface. Find the e-field at a point h on the z-axis. Homework Equations d\vec{E} = \frac{1}{4\pi\epsilon} \frac{dq}{R^2}\hat{R} The Attempt at a Solution Can...

Who can slove this one: f(x) = [ln(x) {{1-e^(3x)}^3}] / [{1+e^(3x)}^3x] f '(x) = ¿¿¿¿??

This is more of a question for study purposes...I've been studying a little bit for my Dynamics exam, but I just don't feel like doing these problems is going to prepare me for the exam well. Does anyone know of a good online source for dynamics problems?

I have a SATA hard drive that I need to format, but the only person I know with a SATA system is my boss...so when he left today, I opened his computer. He has two SATA hard drives, and I unplugged one and connected mine. It didn't recognize the new disk, and plugged his back in. Although I...

Homework Statement There are n > 3 points in the plane such that any three of the points form a triangle of area \leq 1. Show that all n points lie in a triangle of area \leq 4. Homework Equations None. The Attempt at a Solution This is hard to discribe since it is...

Homework Statement A trough has an isosceles trapezoidal cross section as shown in the diagram. Water is draining from the trough at 0.2m^3/s At what rate is the surface rea of the water decreasing? Dimensions are: base width=0.4m, top width= 0.8m...

Homework Statement I have a linear map T:M(2x2) -------> M(2x2) defined by T(B) = [2 3; 4 0] * B Find a 4 × 4 matrix representation of this linear transformation with respect to the basis of M(2×2) Homework Equations T(B) = [2 3; 4 0] * B and the basis for M(2X2) is: [1 0; 0...

The hard iron bar called irony, that is. The irony of toothaches. My sadistic dentist informs me, my wisdom teeth are coming in all wrong and will necessarily need amputation. Poor hypocrite me, I had declared I'd sooner die naturally than go under the knife; now I've given in, to schedule the...

A "Possibly easy for you, but hard for me" Question about Sudoku How to calculate the maximum number of valid patterns on a 9x9 Sudoku board? I was coding a flash application which is basically a "sudoku solver". This question is not related with qhat I'm doing but just curious. Please...

I need to know how to completely wipe my Hard Drive on a Windows XP. There is a virus that will not get off no matter what I do, I have run all antivirus and antispyware devices there are and I would much rather wipe my HDD right now. So anyone know anything I could do.

Interesting problem I came across, yet I'm having some trouble with it: Here are a few of the next generation of experiments currently being planned for constraining cosmological models. Not all of these are groundbased: DES:https://www.darkenergysurvey.org/"...

Hi, so recently I bought an external hard drive and started transferring my data into that to get more space in my internal one. I then noticed that I've used up almost 50% of my c drive but I don't know what it's used for and don't see anything that would use up this much memory. Is there any...

I am currently a student in a Engineering based calculus class and well things are about average in terms of my performance, Just there is one thing that I just don't get and for that matter have never gotten. That is trig functions, I just don't understand them. I've tried memorizing and...

Hi I tried this question a couple times, couldn't figure it out, thought maybe you guys could help. 1. The maximum load that can safely be supported by a rope in an overhead hoist is 400N. What is the maximum acceleration that can safely be given to a 25kg object being hoisted vertically...