Stuck Definition and 858 Threads

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.

Hello everyone I need some help in performing the following integration (not HW): \int_{0}^{\pi/4}\left(\frac{x}{x\sin x + \cos x}\right)^{2}dx I tried integration by parts, but it leads nowhere. Any suggestions would be appreciated. Thanks Vivek PS--Mathematica gives the answer as...

I'm trying to do the following: int (3x^3 + 4x)/(x^2+1)^2 dx I let u = x^2+1 and I eventually get: int 3(u-1)+4/u^2 du/2 When I further break this down, I get: 1/2 int 3u^-1 -u^-2 du am I on the right track? When I integrate this, I'm thinking that I have to be doing something...

here is the question: A race car driver sets out on a 100-kilometer race. At the quarter-way marker, her pit crew radios that she has averaged only 60 km/hr. How fast must she drive over the remaining distance in order to average 100 km/hr for the entire race? please help me out, I have...

Homework Statement Homework Equations Show that the equation \frac{2}{x+1}+\frac{1}{x+2} = \frac{1}{2} can be written as x^{2} + x - 4 = 0 The Attempt at a Solution mulitply the fractions on the LHS numerators by opposite denominators and multiply denominators togethter...

Homework Statement Let e_i = (0,0,\ldots, 1, 0 , \ldots) be the basis vectors of the Hilbert space \ell_2^\infty. Let U and V be the closed vector subspaces generated by \{ e_{2k-1}|k \geq 1 \} and \{ e_{2k-1} + (1/k)e_{2k} | k \geq 1 \}]. Show U \oplus V dense in \ell_2^\infty I am...

If a first pump is used for 2.2 hours and a second pump is used used for 2.7 hours,32m cube can be removed from a waste water holding tank. If the first pump is used for 1.4 hours and the second pump used for 2.5 hours,24m cube can be removed. How much can each pump remove in 1 hour ?. What is...

I was downloading a new OS onto my Titanium the other day and after it downloaded about 25%, it gave me some error and canceled downloading. Now, my Ti-89 is stuck in a "Waiting to receive..." screen. Left+Right+2nd+On doesn't work, and neither does taking out the batteries and putting them back...

I think it's safe enough to say everyone sometimes gets stuck on a new concept or a problem. When this happens, how do you react? Do you just move on, or insist? Do you get frustrated or remain calm all throughout? I for one get very uncomfortable (almost to the point of being tormented), get a...

After reading the example of a current carrying wire frame "carrying up" a weight in Griffiths's EM book (#ch 5,p-210) a numerous times,...,just now it seems to me that I missed an important point to note earlier. I am quoting from him."...but now it also has a horizontal component (quB)...

Homework Statement The ionisation energy of Li is 5.39eV and the electron affinity of F is 3.40eV. Give a lower bound for the modulus of the crystallisation energy of Li+F- Homework Equations Not entirely sure of the equation to use, but have this one in my notes: U = -...

OK, I have this complex number equation: 5\,V\,=\,\left[\left(j2\,+\,1\right)\,\left(1000\,-\,j10000\right)\,+\,\left(200\,+\,j2000\right)\right]\,i_L Now I try to solve for i_L: i_L\,=\,\frac{5\,V}{\left(j2\,+\,1\right)\,\left(1000\,-\,j10000\right)\,+\,\left(200\,+\,j2000\right)}...

Hoping someone can help me here quickly. Trying to get this one question. a perfect gas is compressed adiabatically from 100 kPa and 17C to a final pressure of 500 kPa and final temp of 77C. The work done during the compression is 45 kJ/kg. Calculate the values of gamma, Cv, R and the...

1. The problem Find the definite integral. \int \frac {t^2 - 3}{-t^3 + 9t + 1} dt2. The attempt at a solution The answer is the book made it seem like the rule \int \frac {du}{u} = ln|u| + C was used. Here's what I got: u = -t^3 + 9t + 1 du = -3t^2 + 9\;dt -\frac{1}{3}du = t^2 + 9\;dt...

Homework Statement \int\frac{1}{t^4+16}\,dt Homework Equations Various integration formulas. I am pretty stuck.The Attempt at a Solution I have tried various substitutions, with no success. I tried t^2 = 4u, hoping to get it into the form 1/(u^2+1) so I could use the arctan formula, but then...

Hello. I am stuck with linear difference equations and i would like some help. I was given that y(k) = y(k)homogeneous + y(k)particular and i am asked to solve the linear equation: y(k+1) + y(k) = k with initial condition y(0) = 0 the homogeneous solution is y(k+1) + y(k) = 0 n + 1 =...

Homework Statement Homework Equations As in the image above The Attempt at a Solution I had a go but i rubbed it off the sheet. Can someone take me through this step by step on how to solve it Thanks

Homework Statement Find \int \frac{x^{2}+3x+7}{\sqrt{x}}dx Homework Equations The Attempt at a Solution I am reviewing for a test on tuesday. I can't see a good algebraic method to solve this using the fact that \int f(g(x))g'(x)dx=F(g(x))+C so I am starting to think it...

Homework Statement Suppose that you wish to fabricate a uniform wire out of 0.900 g of copper. If the wire is to have a resistance R = 0.700 ohm, and if all of the copper is to be used. (a) What will be the length of the wire? M Homework Equations R = pL/A R = .700 ohm and p =...

stuck on Change of Phase problem How much ice at 0 degrees Celsius must be mixed with 50.0 g of water at 75.0 degrees Celsius to give a final water water temp. of 20 degrees Celsius? ive been trying to work this out for the past hour, but having trouble...any help would be appreciated.

1. Suppose a constant potential energy,Vo, independent of x and t is added to a particle's potential energy. Show that this adds a time-dependent phase factor, e^{-iV_ot/\hbar}Right now I'm completely lost. Here's what I think so far: 2. i\hbar\frac{d\Psi}{dt} =...

Homework Statement You don't need it verbatim. I'm just trying to solve for the eigenstates and eigenvalues of the Hamiltonian for a one-dimensional infinite square well, with a particle of mass M inside. I'm embarrassed to say it, but the question is throwing me off because the infinite well...

Info A model train has an electric motor to drive it. The current though the motor is controlled by a rheostat and when it is moving slowly the current is 0.5A and the voltage is 5V. Data Total Power = 6W Power Developed By Motor = 2.5W Power Absorbed By Controller = 3.5W Total Voltage...

Homework Statement a body mass of 5kg starts off from rest and is acted upon a force of 5N over a distance of 2m. if there is no frictional forces make use of the principle of the conservation of energy to determinei ts final speed Homework Equations above is all i have. The...

I am stuck on a problem that is probably was easier than I am making it out to be, but I am wondering if anyone can help me out. The question is: How many feet are in a light-second. I would appreciate some help with this problem, 'cuz I have attempted this problem many times, but still am...

I actually managed to get my Jeep stuck last night ... in a parking lot, no less. That's the first time I've ever managed to get stuck. It was hard to gauge the depth of the snow in an unplowed lot, and I wound up a little too close to the building where the snow was a little deeper. That...

Homework Statement "An 80.0 kg skydiver (initially at rest) jumps out or an airplane at an altitude of 1000.0 m and opens the parachute at some altitude. Assuming that the totalretarding force on the skydiver is constant at 50.0 N with the parachute closed and the constant at 3600.0 N with...

Homework Statement How many wavelengths of radiation emitted by a 60 Hz electrical transmission line would it take to span the North American continent (a distance approximation 5.0*10^3 km). f=60Hz d=5.0*0^3 km=5.0*10^6 m Homework Equations v=fλ Δd=vΔt The Attempt at a...

Just stuck on a few problems on my homework, any help? 1. How many different sets of quantum numbers are possible for an electron for which: a) n=1 b) n=2 c)n=3 d)n=4 e)n=5 2. For a hydrogen atom in its ground state, use the Bohr model to compute: a) the orbital speed of the...

I've been trying to invent a formula for solving certain sides and angels on objects... and I've tried many different ways to get the formula for it, I think I might have it, but there's this one line I can't figure out how to solve... help would be appreciated. -4 ln | (csc53 + cot53) = -3...

a car pulling 20,000pounds accelerate uniformly from a rest to a speed of 40 miles/hour in 12 seconds (a) find the distance (infeet AND miles) that the car travels during this time (b) find the constant acceleration in ft/s^2 of the car part a i get 480 feet is this correct i then...

Hello, I am an engineering student doing my first real engineering project with a group of other engineering students. To give a background of my issue, I am charged with the task of designing a system which is able to detect when a rotating shaft spins too fast and send an appropriate...