Stuck Definition and 836 Threads

Homework Statement An laser is used of wavelength 544 x 10^-7 m (in air) for eye surgery. The index of refraction of the fluid in an eye is n = 1.43. Calculate the frequency of the laser waves in the eye. n = 1.43 L1=544 x 10^-7 L2= f = Homework Equations n=L1/L2 L1 being the wavelength...

Circular arc--badly stuck I have a circular arc defined by 3 points [start point, intermediate point an end point]. I know the radius of the circular arc too. I know the angle subtended by the start and end point at the centre. I do not know the center of the circle Now, I want to...

A total amount of positive charge Q is spread onto a nonconducting, flat, circular annulus of inner radius a and outer radius b. The charge is distributed so that the charge density (charge per unit area) is giver by o = k/r^3, where r is the distance from the centre of the annulus to any point...

Hi, I am graphing a hyperbola and have completed everything, except I am not to sure how to draw the final curve in. I have the center, foci, vertices, and axis'. I cannot seem to find any information on actually plotting the curve in. Am I supposed to freehand it in from the vertice and follow...

Okay so there are four numbers represented by A,B,C,D. Their sums when adding three of the four equal the following sums.. 20,22,24, and 27. This is what I have discovered so far but am really stuck. a+b+c+d=x 20= b+c+d or 20= x-a 22=x-b 24= x-c 27=x-d Thanks in advance to anyone who can...

I'm at the last equation of my homework and I'm stuck Homework Statement In a nuclear reactor, a neutron moving at speed vo (vo is initial speed) in the positive x direction strikes a deuteron, which is at rest. The neutron is deflected by 90 degrees and moves off with a speed vo/*square...

hey guys, I'm not sure how to start these off. Can someone give me a hint? I'm not sure how else to show these (they have circuit pictures). The questions are numbers 18 & 24 here http://www.physics.brocku.ca/Courses/2P31/DH-Asst1.pdf . thanks in advance :)

Homework Statement Give an example of a function f:R^2 -> R such that f(av) = a(f(v)) for all a in R and all v in R^2 but f is not linear. Homework Equations f(v + w) = f(v) + f(w) (Additivity) The Attempt at a Solution I really can't think of a function that will satisfy these...

[Solved] Some very tough integration problems I am stuck on. Got these for homework the other day and they are due today! I am having trouble on where to start with all of them. \int x^{n}lnx dx \int sin(\sqrt{x}) dx don't even know where to start on this one... should I substitute...

[SOLVED] Stuck on damped pendulum question... Homework Statement A pendulum of length 1.00m is released at an angle of 15.0 degrees. After 1000 seconds, it's amplitude is decreased to 5.50 degrees due to friction. What is the value of b/2m? Homework Equations w = \sqrt{w_{0}^{2} -...

[SOLVED] I'm stuck with college physics My college professor decided he didn't want to teach this chapter on Motion in 2D and 3D so he left us to teach ourselves. My first question is this A stone is catapulted at time t = 0, with an initial velocity of magnitude 19.6 m/s and at an angle of...

Homework Statement A soccer player kicks a rock horizontally off a 40.0 m high cliff into a pool of water. If the player hears the sound of the splash 3.07 s later, what was the initial speed given to the rock? Assume the speed of sound in air to be 343 m/s. The Attempt at a Solution...

Homework Statement This is to find the arc length of r= \theta from 0 < \theta < 2pi I ended up with \int\sqrt{\theta^2 + 1} Homework Equations \int\sqrt{\theta^2 + 1} The Attempt at a Solution I couldn't see a relevant way to do integration by parts so I went with trig...

Hi, I don't know what to do, and am stuck on this question. Let f(x) = {x^2+4, x does not equal 1 (left?) {1, x=1 (right?) Lim F(x) x->1 First it gives a graph. A parabola but at x=1, y=5, there is an open dot, (hole in the graph) so it cannot equal 5? and then there is the random...

[SOLVED] Larson 4.1.10 Homework Statement Determine all triplets of integers (x,y,x) satisfying the equation x^3+y^3+z^3=(x+y+z)^3 Homework Equations The Attempt at a Solution I think the only solutions are x=y=0, x=z=0, z=y=0, z=-y and x=0, x=-z and y=0, x=-y and z=0. If I...

All, Hey, it's been a while since I've posted, but I have a problem that I am having a hard time moving forward with. I know there are some really intelligent algebra folks in here, and it would be great if someone could help me with this. The equation is kinda large, but there are other...

Homework Statement I am trying to work out the force which a mass applies when it drops from a known height onto another object. Homework Equations F=ma suvat: v^2 = u^2 + 2as F= change in momentum/time and possibly KE= 1/2mv^2 The Attempt at a Solution I don't think that F=ma...

Sorry to bother with yet another question today, but I'm a little lost with this one. QUESTION A box with a mass of 25 kg is at rest on a ramp inclined at 45 degrees to the horizontal. The coefficients of friction between the box and the ramp are us=0.78 and uk=0.65. a) Determine the...

Homework Statement A uniform beam of 6.6 meters with a weight of 42.67 Newtons is pinned to a wall and supports a weight of 19.62 Newtons.The beam is angled up at 16 degrees and the right end of the beam is supported by a cable attached to the other side of the wall. Find the value of; Tension...

Homework Statement I am working on 6.16 at the following site: http://mikef.org/files/phys_4241_hw14.pdf I think that the solution given is given is wrong. I can get part a), however, I am just getting stuck on part b). So, the wavefunction in r < r_0 is R(r) = A/r sin(k_1*r) and the...

In the middle of doing an integral for Calc 3, and I came across (9-3x)^3, and completely forgot how to do this from algebra! Help!

Homework Statement An object with a mass of 10 kg (this mass is m1) rests on a horizontal table and is connected to a cable that passes over a pulley and is then fastened to a hanging object with mass of 4.0 kg (this mass is m2). The coefficient of static friction between m1 and the...

Just asking the PF members out of interest (and because this stupid Dragonforce song won't go away). Which songs always get stuck in your head?

I am stuck on a problem.. I keep obtaining the incorrect answer and I am unsure of where my calculation went wrong? I have the 2 vectors v1 [4,0,3] and v2 [25,0,-25] I first obtain (1/||v1||)v1 = [4/5 0 3/5] = z1 I then proceed to do: (v2 - (z1 . v2)z1)/||v2 - (z1 . v2)|| = [25 0 -25] - 5...

Homework Statement http://img511.imageshack.us/img511/3732/dynamics01fm7.jpg Homework Equations F = M x A F = u (coefficient of friction) x N The Attempt at a Solution http://img508.imageshack.us/img508/7526/dynamics02ry1.jpg W sin 30 = 50000 W cos 30 = 86602.54 1Mg =...

PDE with boundary conditions Full question A function u(x,y) has two independent variables x and y and satisfies the 1st order PDE x \frac{du}{dx} - \frac{y}{2}\frac{du}{dy}= 0 by first looking for a separable solution u(x,y)=X(x)Y(y), find the general solution of the equation. determine...

In an effort to pull a stuck car out of the mud, the driver ties a 10m rope to the bumper and a nearby tree. He then pushes with a force of 200N on the center of the rope? a) If he moves 1.0m, the force pulling on the car at that time will be ? b) the distanced the car moved is ...

A quarter-circle of radius R, block A mass M is release from the top of the quarter-circle, slide down the curve section. And collide inelastically with identical block point B. The two blocks move together to the right and stop with the distance L. The coefficient of Kinetic energy between the...

A 0.25 kg pine cone falls from a branch 20 meters above the ground. a) What speed would it hit the ground if the air resistance could be ignored? I am not too sure how to do this but this is what I've got so far: m=0.25 g=9.8 m/s^2 F=2.45 J h=20 m Ep=(0.25kg)(9.8m/s)(20m) Ek=1/2mv^2...

Homework Statement An alien form of frog with a mass of 1.5kg (on a planet with an unknown acceleration of gravity) jumps up from his lilly pad at a velocity of 4.0m/s. If the frog reaches a maximum height of 15m, what is the force of gravity on the frog on this planet? It's a stupid...

For the integral from 0 to infinity of xe^(-5x)dx... I am getting as far as: -1/5*x*e^(-5x) + 1/5*int of (e^(-5x)dx) But I am getting stuck at this point. We are supposed to come out with 1/25 for the answer but how would I evaluate the "-1/5*x*e^(-5x)" since that is already out of...

Limits - Please Help! I have been set 4 questions, i basically have no idea if the ones i have tried are correct and have no idea how to even start the other 2. Any help would be much appreciated. I have scanned them in (easier than typing i think)...

Homework Statement Halliday/Resnick/Walker, 1 - Mechanics, 7th Edition. Chap. 4, Exercise 57 - Relative Movement in One Dimension (I'm sorry if translation sounds confusing at first, the book is in Portuguese) A suspicious man runs as fast as he can on a conveyor belt, taking aprox. 2.5...

Suppose the spring has a spring constant of 350 N/m and the box has a mass of 1.8 kg. The speed of the box just before it makes contact with the spring in 0.43 m/s. What is the algebraic expression for the magnitude of the spring's displacement at the instant when the acceleration of the box...

I don't know what i want to do with my life. I find science fascinating and interesting. But I really don't like studying it. I was going into nanotechnology as of lately. But now I feel like making movies. I have the visual ability and I am good at picturing an outcome. My mother is an...

Homework Statement You are riding on a jet ski at an acute angle upstream on a river flowing with a speed of 2.8 m/s. If your velocity relative to the ground is 9.9 m/s at an angle of 26.0° upstream, what is the speed of the jet ski relative to the water? Homework Equations...

Homework Statement A car initially traveling north at 35 m/s, brakes and turns to avoid an obstacle so that 3 seconds later it is traveling northeast at 20 m/s. Find its average accelera- tion during the period of braking and turning. Homework Equations acceleration=change in...

Homework Statement If X is a metric space such that every infinite subset has a limit point, then prove that X is compact. Homework Equations Hint from Rudin: X is separable and has a countable base. So, it has countable subcover {Gn} , n=1,2,3... Now, assume that no finite sub...

Homework Statement A uniform rope 12.0m long and with a mass 3.00kg is hanging with one end attached to a gymnasium ceiling and the other end just touching the floor. The upper end of the rope is released, and the rope falls to the floor. What is the change in the gravitational potential...

To appreciate the forces that a fighter pilot must endure, consider the magnitude of the normal force that the pilot's seat exerts on him at the bottom of a dive. The plane is traveling at 252 m/s on a vertical circle of radius 616 m. Determine the ratio of the normal force to the magnitude of...

This isn't a hard question I am sure, but I am new to circuit diagrams and need them as part of my product design course, so any help would be much appreciated. Homework Statement Find the currents which are flowing in the 14Ohm and 10Ohm resistor...

Homework Statement An adult 68.0kg cheetah can accelerate from rest to 20.1 (45.0mph ) in 2.00 s. Homework Equations F=MA Vf=Vi + (a)t The Attempt at a Solution Assuming constant acceleration, find the net external force causing this acceleration i solved for the time using...

... but after reading a few topics here, I thought some of you might help me get things cleared. First, don't pay too much attention to English mistakes, as this is not my mother tongue. I'll do my best. I love someone. A girl. Although I'm not quite sure what's the exact feeling of love...

You are arguing over a cell phone while trailing an unmarked police car by 36 m. Both your car and the police car are traveling at 110 km/h. Your argument diverts your attention from the police car for 2.5 s (long enough for you to look at the phone and yell, "I won't do that!"). At the...

Homework Statement A metric ton is 1 times 10 to the 3rd power how many 86kg ppl can safely occupy an elevator that can hold a maximum mass of exactly one metric ton? answer in units of ppl The Attempt at a Solution i divided 1000kg by 86kg to get 11.627 people when i enter that as...

hi guys, I'm solving a pretty complex problem: calculating a trajectory of a charged particle in a custom magnetic field. I arrive to the point where this very nice equation system blocks my way :P http://ramses728.altervista.org/img/phys.jpg hope you can help me somehow

(moved to Intro Phys... - Doc Al) ---------------------------------------------------------------------- Hi guys, this is my first post in this forum. I feel lucky to come across a place like this and even more thankful if i can get help on this problem that I've been spending a loooot of...

Easy problem that I am stuck on... Homework Statement Two vectors A and B have magnitude of A = 3.02 B=3.00. Their vector product is AXB = -4.90k + 2.01i. What is the angle between vector A and vector B? Homework Equations since I know the vector product of A and B, I was thinking that...

hi, I've been searching around the site and found it pretty useful but I'm having a pretty tough time with a few questions i have its pretty much the same as This but the coefficient values are different, the problem I'm having is with the coefficients for the bends, could someone please...

I went for a test ride on the bike, and now i can not get my right boot off, i have struggled till i am red in the face, it is as if the boot has shrunk, it is over an hour since my ride and i feel silly walking around with one boot on.