Homework problems — 47 discussions

I am an electrical engineer and I like to educate high school physics

I created a Vector which describes the direction of the medium. with r=(x(t),y(t))=((x0+cos(b)*t+0*t^2/2),(y0+sin(b)*t-9.81*t^2/2)) I created a vector for the acceleration a=(0,-9.81) Now only the y(t) is relevant since x(t) acceleration is zero. sin,cos describe the direction of the velocity...

I am attempting problem number 2.38 from John R. Taylor's Classical Mechanics and I am not getting the correct answer. My procedure is as follows: Equation of motion (taking up as the positive direction): $$m\dot{v}=-mg-cv^2$$ Now to find ##v_\mathrm{ter}##, the terminal velocity, we consider...

Hi, good evening/morning/night! I have a problem with this 2 homework problems about curved beams. In both I must calculate the stress at points A and B. My procedure is correct, but for some reason in: First problem - the effort in A is very close to that of the teacher, but the effort in B...

I'm stuck on a few Vector homework problems. I don't quite understand how to write vectors A+B and A-B for questions 1b and 2b. I tried starting with calculating the magnitude for vector A+B on question 1b and then followed by finding theta, but I'm not sure if that's what I'm supposed to do...

I’m having lots of trouble in my honors physics class with the theoretical homework problems that are assigned. The entire concept of learning to solve things theoretically, and then applying it is brand new to me. I’m decent at figuring out the applied problems, but pure theory stumps me. I...

Homework Statement Hi guys, I've been trying to solve these two questions for the last hour and can't seem to find the solution, any help would be very much appreciated. :smile: 1. An RC circuit is given a step voltage (charging) of V at t = 0 seconds. What is the value of voltage at t = 2RC...

hi I don't understand how to do one type of homework problem, here's an example of the type: If limit of f(X)/X = 1 as X ->0 evaluate the limit f(X) as X->0

I am an advanced undergraduate student, and I still remember the days when I could open my mathematics textbooks, read through a few sample problems, and then blaze my way through the exercises with little or no help. Come university, and my freshman year, and things changed dramatically. I...

[Mentor's note: this post does not use the homework template because it was originally posted in a non-homework forum.] ----------------------------- A ship (attached to reference frame S') is passing us (standing in reference frame S) with velocity v= 0.933c. A proton is fired at speed...

When I'm doing the Physics homework the problem for heat of vaporization uses Q=mcΔT and Q=mLv. How do I know when to use which equation through out the problem?

Just joined. I've been slowly working my way through Susskind's Theoretical Minimum books, so I'll be looking for discussions of those and his lectures on the same topics. I have a lot of scientific interests, including fundamental physics, mathematical biology, economic geology, electronics...

Homework Statement Hi there! So I'm working on an old homework problem for review so that I actually have the solution, but I'm not sure how to compute a certain part. Here it is: $$\int \int rcos^2(\theta)dr - r^2cos(\theta)\sin(\theta)d\theta$$ Homework Equations The solution involves (what...

Hello everyone, For homework my instructor assigned problem from the book. To show which problems to do she wrote this: 4n + 1 N={1, 2, 3...}. Does this mean problems 5, 9, 13, . . . ? Thanks for any suggestions.

Homework Statement Is there an equation which I can use to calculate this? Homework Equations The Attempt at a Solution I think the SI units for pressure are kgm^-1s^-2 but that's all I know. I have tried to put numbers into that to get an answer but I can't get it to work. Thanks.

Homework Statement I need to prove that \frac{\frac{1}{2} cot20^{o}-cos10^{o}}{\frac{1}{2}+sin10^{o}}=\frac{\sqrt{3}}{3}The Attempt at a Solution I try to do it by this way \frac{\frac{1}{2}...

I'm a physics teacher. Do you know of any available physics problem books or sources (free or otherwise) for: * intro level, lite-algebra high school applied physics course * standard high school algebra-based physics course (AP Physics B) * standard high school calc-based physics course...

Homework Statement 1. A ball is tied to a string then moved so that its trajectory is vertical circle. If the mass of the ball is 500 g, the speed is 2 m/s, and the length of string is 50 cm, find the tension when it is at the top of the trajectory 2. A mass m is tied to a string and moved so...

Homework Statement What is the emf E of the battery at the lower left in the figure? Answer in units of V. http://img508.imageshack.us/img508/6/82852928.png Can someone guide me? I'm confused as to where to start. I think I am supposed go the route of the loop, but I am given the...

Hi guys, I realize this can be a rather uncanny occurrence when a new member's first post is to ask for physics help on his homework but I've been lurking around the forum here for a while and am now in a really tight spot and thus had to get over myself and finally make an account...

Hi everyone, Can anyone show me how the property \frac{1}{2\pi} \int ^{\infty} _{-\infty} e^{i\omega x}d\omega= \delta(x) holds. Thanks,

Homework Statement I am trying understand the approach to the problems given in the following textbook. Linear Operator Theory in Engineering and Science (Applied Mathematical Sciences) (Volume 0) [Paperback] Arch W. Naylor (Author), George R. Sell (Author). Pages 12-29. There are exercise...

Homework Statement ok I am going to supply some preps I got from exam(all that i remember) and I want you to estimate the degree of roughness Find the square roots 1) |z|9+27=0 2)find homogenus system x+y-c+2z=0 -x+2y+c+z=0 x+y+c+z=0 2x+y+c+2z=0 ------->im not sure but...

[SIZE="5"]Disclaimer: [SIZE="4"]This is a college course of mine in which the homework is scrutinized by the professor and worth 30% of our grade. I've done all the homework problems by myself except these 2. Do not, in any way, tell me how to do it. It's okay to explain something that my...

Homework Statement Hi, I have been having huge problems with dealing with these kinds of problems, I would appreciate atleast some guidance in dealing with these sorts of problems, I think the major problem is just how I learned to solve them, I have been looking for resources on the net, but...

homework problems... About how big is one Quark?

Hi, These are not homework problem, but problems from my textbook. I am studying for a final exam in 2nd year Modern Physics that is on Monday and need some help with question. This set will be about special and genreal relativity, and I'll post another on quantum physics. 1). How fast...

I need help with how to solve these problems on my homework. If you don't know how to do them all then just write the number of the one you know. Thanks so much. 1. arcsin(√3 / 2)= 2. sin^-1(- √2 / 2)= 3. arcos(- 1/2)= 4. tan^-1(√3 / 3)= 5. sin(arctan 3/ 4)= 6. If the sun is 30degrees...

Homework Statement http://img114.imageshack.us/img114/9822/questionta3.jpg http://g.imageshack.us/img114/questionta3.jpg/1/ Homework EquationsThe Attempt at a Solution http://img181.imageshack.us/img181/2928/workingkz5.jpg May I know which part of my solution went wrong? In the end the...

Hey guys this is a practice problem for my lab and i can't get it can someone please help: The force sensor measures the force on the sensor due to the bumper, but the cart's momentum change arises from the force on the cart due to the bumper. Which of the following facts are needed to assert...

FIRST PROBLEM Homework Statement A skier of mass 70 kg is pulled up a slope by a motor-driven cable. (a) How much work is required to pull him 60m up a 30 degree slope (assumed frictionless) at a constant speed of 2.0 m/s? (b) What power must a motor have to perform this task? Homework...

[/B]Homework Statement rower a wishes to cross a river directly to the oposite bank (east) a distance of 30mtrs (90 degree's to the shore) the current is flowing NS at 2.6m/s and he can sustain a rowing speed of 3m/s 1. calculate the direction with respect to the current flow he needs to...

Homework Statement Evaluate the integral 3x^2e^xdx The Attempt at a Solution I used integration by parts twice and came up with: 3x^2e^x-6xe^x+6e^x+C Does that look correct. Another question ask for a divergent series whose terms go to 0. The harmonic series 1/n (with...

So our latest E&M homework assignment out of griffiths has a bit of a twist. For all of the answers that we get we have to show that they seem reasonable. I know for instance with a charged solid sphere of radius R you could take R<<r where r is the distance away from the sphere and see that it...

PhysicsForums.com: Shining a flashlight out of a spaceship won't make the light travel faster than c. PhysicsForums.com: I can't believe it's not Newtonian Physics.

Going through these last few multiple choice HW problems tonight (about 50 of them total to finish tonight and I am down to these alst few)...and wondering if these are correct: 1. Newton's First law states... a) An object can only move in a circle if external forces act on it. b) An...

Help with homework problems please! A cannon is mounted 50m away from the edge of a cliff that drops 10m to the plain below. If the cannon projecticle is fired with an initial velocity of 75 m/sec find the angle of elevation so that the shell lands closest to the cliff face from the plane below.

mark the correct alternative : The electric potential decreases from 120V to 80V as one moves on the X axis from x=-1cm to x=1cm . The electric field at the origin a) must be equal to 20V/cm b) may be equal to 20V/cm c) may be greater than 20V/cm d) may be greater than 20V/cm i think all...

#1) The coefficient of static friction bwtween the block and the board is 0.6. If the blocks weight is 75 N, what minumum weight attached to the pulley will cause the block to move? #2)Find the direction and acceleration of a single pulley with 2 masses (7 kg and 10 kg) #3)A machine...

I have soluted these so but I need an explanation of what I've done. An even 2,23m long plank is turn-able around its one end. The plank is hold up in an horisontial way with a vertical upp-force on 268 N The force works at 1,52 from the turn-able point. Decide the planks mass. What I did...

Infinite Series Calculus 2 homework problem Hello. I need help finding the answer on two of these. #1. Find a power series representation for f(x)=ln(1+x^2) I have f'(x)=\frac{(2x)}{(1+x^2)} So I factor out 2x and have \frac{1}{(1+x^2)} which is a geometric series = \sum(-1)^{n}x^{2n}...

Please help I'm totally lost an i don't understand how to do these problems. Could u please explain these problems out so i can better understand them and solve too.I am failing physics right now that's how clueless i am about this subject. 1. Consider two uniform solid spheres where both...

[FONT=Arial]For some reason I just don't get my dynamics homework. Here are the few problems I am having. Problem 1: A river is flowing north at 3 m/s (uniform current). If you want to travel in a straight line from point C to point D in a boat that moves at a constant speed of 10 m/s...

I'm on static/kinetic friction, tension force, and Equilibrium applications of Newton's Laws of motion. I have many homework problems that baffles my mind and need serious help understanding them. So, any help will be appreciated. 1] 'A large cube (mass= 25 kg) being accelerated across a...

Some chapter review problems in the back of the book I was having trouble with. Any help is appreciated. (Not asking for answers but directions and formulas explanations if possible) Thank you! 1) The Empire State Building in New York City oscillates in the wind with a period of 8 seconds. Do...

I figured out the capacitor/charging problem that I last posted. Here's my latest cause of worry: 1)The Resistance of the coil of a pivoted-coil galvanometer is 7.92 Ohms and a current of .0194 A causes it to deflect full scale. We want to convert this gavanometer to an ammeter reading 10 A...

Can i post a list of my homework problems (not to get answers or anything) but to give me pointers on problems?