Initial Definition and 1000 Threads

Homework Statement 3y'' -y' + (x+1)y = 1 y(0) = y'(0) = 0 Homework Equations Not sure, that's the issue The Attempt at a Solution I can't quite get this one using the methods I'm familiar with, and I can't guess a particular solution to neither the equation nor the...

Homework Statement A block with mass m = 7.4 kg slides down an inclined plane of slope angle 43.8 ° with a constant velocity. It is then projected up the same plane with an initial speed 3.10 m/s. How far up the incline will the block move before coming to rest? The attempt at a...

Hi All, It's been a looong time since I've had to use/apply basic physics but I'm hoping I've come to the right place for help. I am trying to help my brother-in-law with a speeding charge. First question The police allege he reached 100km/h within 38m of a corner. The first...

So the question I'm asking about is actually from my analytical mechanics class, but I think my question is really more of a gen. physics question. Basically, in this question we have a cannon ball, diameter(EDIT:but not mass!), fired with a given muzzle velocity, and we are given the cannon...

Hi I need to find the horizontal distance traveled by an aircraft just after take off to a vertical height of 10.7m. The rate of climb is 1920m/min. I'm not really sure how to approch this question. I think simply it would look like a right angles triangle, I would need an initial velocity...

Question: Find y as a function of x: x^2 y'' + 8 x y' - 18 y = x^8 y(1)=3, y'(1)=2 Attempted solution: I found the general equation to be Ax^(-9)+Bx^2+Cx^8. However when I try to solve the initial value problem for this equation I have 3 unknowns.

Homework Statement Consider the PDE xu_x + y u_y = 4 u, -\infty < x < \infty, -\infty < y < \infty. Find an explicit solution that satisfies u = 1 on the ellipse 4x^2 + y^2 = 1. Homework Equations The Attempt at a Solution The characteristic curves are x(t,s) = f_1(s) e^t...

The questions arises because I want to use the solution of one PDE as initial condition to solve another. Then using NDSolve, the first solution is given by InterpolatingFunction. I tried, it takes the whole afternoon, almost kills my computer but still not giving any result. Another computer...

Homework Statement A 20.00kg curling stone is released at the hog line and moves 28.35m [W] to sit on the button and score a point. If the coefficient of kinetic friction between the stone and the ice is 0.0020000, what was the initial speed of the stone ? So we know: m=20.00kg...

The problem: dx(1-y^2)^1/2=dy(1-x^2)^1/2 y(0)=3^(1/2)/2 My attempt: I separated the variables and integrated, and came up with sin^-1(x)+c=sin^-1(y) This is where i am stuck. any suggestions? did I run astray anywhere?

Homework Statement I have found the general solution to a second order pde to be U(x,t) = f(3x + t) + g(-x + t) where f and g are arbitrary functions I have initial conditions U(x,0) = sin(x) Du/dt (x,0) = cos (2x) The Attempt at a Solution I have found that U(x,0) = f(3x) +...

Homework Statement In this problem, we will solve the initial value inhomogeneous differential equation in two steps. y''+4y=2x*e^(3x) y(0)=0 y'(0)=0 1.) First determine yp the particular solution to the differential equation. 2.) Next determine y=yc+yp the complete solution...

Homework Statement I have a PDE for which i have found the general solution to be u(x,y) = f1(3x + t) + f2(-x + t) where f1 and f2 are arbitrary functions. I have initial conditions u(x,0) = sin (x) and partial derivative du/dt (x,0) = cos (2x)Homework Equations u(x,y) = f1(3x + t) + f2(-x +...

Homework Statement A student is determined to test the law of gravity for himself. He steps off a skyscraper 320m high, stopwatch in hand, and starts his free fall. Five seconds later, superman arrives at the scene and dives off the roof to save the student. What must superman's initial...

I'm given the following DE and initial conditions: y''=2yy' y(0)=0, y'(0)=1 I started by doing a reduction of order like so: w=y', w'=y'', \int w=y=\frac{w^{2}}{2}+c which then gave me this: w'=2w(\frac{w^{2}}{2}+c) w'=w^{3}+2wc Now I'm stuck on where to go from here. I can't use any of the...

Homework Statement An arrow is shot at an angle of θ=45* above the horizontal. The arrow hits a tree a horizontal distance D=220m away, at the same height above the ground as it was shot. Use g=9.8m/s^2 for the magnitude of the acceleration due to gravity. Find t, the time that the arrow...

Hi all Another question (sorry) Water vapour in the air will phase shift back to liquid when it reaches its Dew Point temp (Partial Pressure = the Saturated Vapour Pressure), OK I have this. For this phase shift I assume that there are Condensation Nuclei and these nuclei are at a lower...

According to the usual way of applying determinism in physics:- If we know all the intitial conditions of a closed system at time t0, we can fully specify the the system at a time t1>t0. This seems natural and obvious within classical physics, but is it really true? I have never heard of a...

Homework Statement A baseball player throws a ball a distance of 250 ft. If the ball is released at an angle of 45°with the horizontal, find its initial speed. Homework Equations The Attempt at a Solution I don't know where to begin. All i know is that speed is the norm of...

Homework Statement A block is given a push up an inclined plane with an initial velocity. At what time will the speed of the block be equal to the initial velocity again? No varialbes are given. Homework Equations v= v(initial) + at The Attempt at a Solution The final...

Homework Statement A woman running at constant velocity speeds up and accelerates uniformly to the west by running 253 m west in 6.12 s. ff she ends up getting up to a velocity of 5.05 m/s w, how fast was she going originally? If she had run the same disance in 5.50 s, what would her average...

Homework Statement A ball is shot from a slingshot and clears a 10 meter fence 130 meters from the point of being flung and lands 10 meters behind the fence. What is the initial velocity of the ball? Assume the ball was caught at the same level it was kicked (delta Y=0). Homework...

Homework Statement A 50.0kg skier starts at A with an unknown initial velocity. The skier then goes over a hill (point B) which is 4.00m above point A. At point B (top of the hill), the skier experiences a Force normal 5/6 of his/her weight. The hill has a radius of 14.6m. What is the...

Because of the kinetic energy and frames of reference thread: https://www.physicsforums.com/showthread.php?t=534883 I was wondering how to show that a change from potential to kinetic energy in a closed system is independent of the (inertial) frame of reference. I think the math below...

I'm trying to help a friend with a physics problem. I've been helping her figure a few out(I always make sure she solves them and understands how she did) but we've hit one that's gotten us both stumped, so I'd appreciate a bit of assistance. The problem is basically, a Diver dives off a...

Why is it that you are able to have 1 initial value problem with 2 solutions, but not 2 initial value problems with 1 solution for an ODE? Is there a theorem that states this?

Homework Statement A rock is thrown downward from an unknown height above the ground with an initial speed of 27 m/s. It strikes the ground 7.1 s later. Determine the initial height of the rock above the ground. The acceleration of gravity is 9.8 m/s2. Answer in units of m. Homework...

Homework Statement See image Homework EquationsSee image The Attempt at a Solution I have tried, but I honestly have no Idea how to start this problem.

Homework Statement A child operating a radio-controlled model car on a dock accidentally steers it off the edge. The car's displacement 0.77 s after leaving the dock has a magnitude of 7.4 m. What is the car's speed at the instant it drives off the edge of the dock? @t = .77s displacement is...

Homework Statement Material ejected to a height of 2.00 x 10^5m. Acceleration of gravity is 1.80 m/s^2, find initial velocity Homework Equations v (zero) = v - at. The Attempt at a Solution Seems as though I am missing something since I don't have time or velocity, yet I have...

I need to find a solution to the following problem: (x^{2}-1)\frac{dy}{dx}+2y=(x+1)^{2} y(0)=0 I decided to try using variation of parameters. My teacher was unable to show any examples, and I'm having issues understanding the textbook. From what I see I need to get it onto this form...

A cannon sends a projectile towards a target a distance 1210 m away. The initial velocity makes an angle 26o with the horizontal. The target is hit. The acceleration of gravity is 9.8 m/s2 . What is the magnitude of the initial velocity? Answer in units of m/s y = viy•t +0.5•ay•t2 vix =...

Hi I need some help with this question: Estimate the maximum initial velocity you can achieve with a tennis ball I thought of using the maximum range formula: R=v2/g but doesn't that imply to the fact that I'm throwing at an angle of 45 degrees? Please help me, I really want to solve this...

How should I go about starting the following two problems solve the following initial value problems x''-4x=0 ; x(0)=1, x'(0)=0 and x''-4x'+4x=0 ; x(0)=1, x'(0)=0 Should i use a general solution with the basis m^2-4=0 for problem one and m^2-4x+4=0 for the second?

Hello all, I got this question off mastering physics and was unable to understand it. I eventually gave up to concentrate on other assignments and asked for the answer. I was unable to come up with more than one answer I thought possible without resorting to trial and error. Answer: Vx,Vy,Vz =...

Homework Statement Tow protons of equal energy collide head on and the result is p+p -----> p+p+ Pi0 If all particles produced at rest what must be the KE of the initial protons Homework Equations mass of Pi0 = 135MeV/c2 The Attempt at a Solution Total energy of the...

Hi can anyone help me with this formula: How do I end up with this equation, thanks in advance!

Homework Statement A juggler throws a ball just so it reaches the ceiling at 3.0 meters. (3m above hand) How do I solve for initial velocity? Homework Equations The Attempt at a Solution

How can you let Initial position and initioal velocity be equal to zero? I understand that it will be zero at time = 0, but as time goes on from 1, 2 , 3 , 4 won't it change? I underlined that it in read in the picture?

Homework Statement A flowerpot falls from the ledge of an apartment building. It takes .2 s for the pot to pass the 4 m window below. How far above the top of the window is the ledge from which the pot fell? (Neglect air resistance) Homework Equations y(t)=y0 + (voy)(t) - 1/2g(t^2)...

Ok so having a little problem with this one and i feel like its easier than what i am seeing, but just not sure how i can get a V-initial from this (Replaced actual numbers with AAA and BBB because i am trying to recall how to do all this, hope ya'll don't mind variables to much lol) The...

For the initial speed of an ideal projectile, how many launch angles equal for the range of the projectile -1 -2 -more than 2 but an infinite number of -only one if the angle is 45 but other wise only 2 -an infinite number

Homework Statement Gamma rays of energy 1.02 MeV are scattered from electrons that are initially at rest. If the scattering is symmetric, that is, if θ = ϕ in Fig. 1, find i. the scattering angle θ ii. the energy of the scattered photons. Homework Equations λ' - λ = (h/mc)[1 - cos(θ)] The...

Homework Statement If a flea can jump straight up to a height of .440 m, what is its initial speed as it leaves the ground? How long is it in the air? Homework Equations x = (1/2)at^2+Vo+xo V + at+Vo V^2 = Vo^2+2a(delta x) x-xo = ((Vo-V)/2)t It has to be one of these, since that's...

Initial angular momentum = 0 when we fall from a height, how does our head automatically reach the ground first than our legs though the initial angular momentum is zero?

Homework Statement Two identical small metal spheres with q1 > 0 and |q1| > |q2| attract each other with a force of magnitude 70.2 mN, as shown. The spheres are then brought together until they are touching. At this point, the spheres are in electrical contact so that the charges...

Homework Statement Find the solution to the initial value problem dy/dx - y = e^3x y(0) = 3 Homework Equations e^∫p(x) The Attempt at a Solution Do I treat p(x) = -1? I(x) = e^∫-1 = e^-x e^-x(dy/dx) - ye^-x = e^3x . e^-x e^-x(dy/dx) - e^-x . y = e^2x e^-x . y = ∫e^2x y = (2e^2x...

Homework Statement Suppose that I am jumping on the Earth, and I weigh 130 lbs. I push off with an initial vertical velocity of 2 m/s, and reach my highest height at 4 m. If I were to jump on a different planet with an extra 130 lbs (earth weight) because of a space suit etc., would I have a...

Homework Statement 1. Find he solution of the initial value problem: x^2 (dy)/(dx) = 4y y(1)=2 2. Find the general solution of the differential equation: (dy)/(dx) - 2y = e^(5x) The Attempt at a Solution i'm completely confused by this, no idea where to start. If...

Homework Statement The position x of an object as a function of time is given as x = 2.257 + 4.894 t + 16.5 t2. All quantities are understood to be quoted in SI units. What is the initial velocity ? Indicate with a negative (positive) sign whether the acceleration is constant (not constant)...