# Search results

1. ### Hydrostatic Force and Pressure

Homework Statement A semicircle with radius 3 m is submerged vertically in water so that the top is 1 m above the surface. Express the hydrostatic force against one side of the plate as an integral and evaluate it I'm not getting the correct answer, so can someone help me to understand my...
2. ### Simple Arc Length Problem

Haha. I apologize. The question I asked was actually very simple compared to the other topics being posted in this forum. The link you sent me looks like cases in which you would use trig substitution (though, that doesn't seem to be how the problems are worked out). But in the problem above...
3. ### Simple Arc Length Problem

Homework Statement x = 1+3t^2 y=3+2t^3 0<= x <=4 Homework Equations L = integral from a to b of \sqrt{[dx/dt]^2 + [dy/dt]^2} dx The Attempt at a Solution dx/dt = 6t dy/dt = 6t^2 L = integral from 0 to 4 of \sqrt{(6t)^2 +(6t^2)^2} dx = " \sqrt{36t^2 +36t^4} dx = "...
4. ### I think it's a conservation of energy problem

I looked up on google what MeV stood for and I saw that it was 1 electron volt times a million. Maybe my source was wrong *shrug*. So is b significant at all in finding the closest distance that the alpha particle comes to the lead nucleus?
5. ### I think it's a conservation of energy problem

So far is this the correct setup? L1 = L2 P0b = p(Rmin) [Rmin is the minimum distance the two particles get to each other] v0b=vf(Rmin) [mass doesn't change so I canceled it] K0+U0 = Kf+Uf K0 = .5mV0^2 = 1 mil(1.602E-19) J [ I can use this to find initial velocity, assuming that I can use...
6. ### I think it's a conservation of energy problem

So then it's just approaching at an angle then? That's the only difference between this and what I described?
7. ### I think it's a conservation of energy problem

Wait... does the alpha particle cause the lead nucleus to rotate?
8. ### I think it's a conservation of energy problem

Homework Statement An alpha particle with kinetic energy 10.5 MeV makes a collision with lead nucleus, but it is not "aimed" at the center of the lead nucleus, and has an initial nonzero angular momentum (with respect to the stationary lead nucleus) of magnitude L = p_0 b, where p_0 is the...
9. ### Electric potential on long insulating cylinder

Nevermind. I think I just need to clear the memory out the memory in my calculator. Thanks a lot!
10. ### Electric potential on long insulating cylinder

So... S = 2\pirh ES = \lambda*h/\epsilon0 E(r) = \lambda*h/(\epsilon02\pirh) h cancles.... E(r) = \lambda/(\epsilon02\pir) And now... v = \int E(r) * dr Is that right?
11. ### Electric potential on long insulating cylinder

Is \intdl the distance from the surface of the insulating cylinder to the point at which I'm measuring potential? I'm guessing not because I'm totally not getting the right answer.
12. ### Electric potential on long insulating cylinder

Homework Statement A long, insulating cylindrical shell of radius .06 m carries a linear charge density of 8.5E-6 C spread uniformly over its outer surface. What would a voltmeter read if it were connected between the surface of the cylinder and .04 m above the surface? Homework Equations...
13. ### Work needed to pump water out of spherical tank

Homework Statement A spherical tank is full of water. If radius r = 3m and height h = 1.5m, find the work W required to pump the water out of the spout. (Use 9.8 for g and 3.14 \pi) Homework Equations Work is the integral from a to b of f(x)dx. The Attempt at a Solution Volume= area *...
14. ### Electric Field: not quite getting the correct answer

Homework Statement E1 = 2.9E4 N/C E2 = 8.6E4 N/C Both fields are uniform Homework Equations flux = \int Eperp*dA = Qencl/ \epsilon0 The Attempt at a Solution flux1 = E1cos(30)(.05m)(.06m) flux2=E2cos(30)(.05m)(.06m) (flux1+flux2) = Qencl/ \epsilon0 Homework...
15. ### Gauss's law; large sheet

Okay, I changed the problem.
16. ### Gauss's law; large sheet

Homework Statement Two very large, nonconducting plastic sheets, each 10.0 cm thick, carry uniform charge densities \sigma1, \sigma2, \sigma3, & \sigma4 on their surfaces, as shown in the figure . These surface charge densities have the values \sigma1= -6.00E-6 C/m^2, \sigma2=...
17. ### Electric Field magnitude problem help

Homework Statement A very long uniform line of charge has charge per unit length 4.88E-6 C/m and lies along the x-axis. A second long uniform line of charge has charge per unit length -2.44E-6 C/m and is parallel to the x-axis at y1 = 0.408 m. What is the magnitude of the net electric...
18. ### Calculating Flux for Hemispheres of Different Radii

How do I open it?
19. ### Calculating Flux for Hemispheres of Different Radii

Homework Statement For some reason, I'm not quite understanding this scenario. " Two hemispherical surfaces, 1 and 2, of respective radii r1 and r2, are centered at a point charge and are facing each other so that their edges define an annular ring (surface 3), as shown. The field...
20. ### Stopping the Proton

"Stopping the Proton" Homework Statement An infinitely long line of charge has a linear charge density of 8.00×10−12 C/m. A proton is at distance 14.0 cm from the line and is moving directly toward the line with speed 1500 m/s. I just want a better understanding of this statement: "An...
21. ### Electric Potential Energy

Ah, never mind. I think it had to do with the fact that the electric field was uniform, so there was only one direction for the force to be exerted. Sorry about that.
22. ### Electric Potential Energy

My book first introduces expressions for work and energy by referring to concepts from mechanics and gravitation. It uses the familiar expressions F =mg (-y direction) & U=mgy to explain the expressions it gives for electric potential energy. However... I understand that the force due to gravity...
23. ### Electric field of a charged ring

I don't know if there's a better way to explain.
24. ### Electric field of a charged ring

Homework Statement This is a http://session.masteringphysics.com/problemAsset/1003223/45/14677_a.jpg" [Broken] of the problem -I know that the direction of the electric field at any point on the z-axis is parallel to the z-axis E = k*q/r^2...
25. ### Charge Distribution on a Conducting Shell

Ah, nevermind. I have discovered the answer.
26. ### Charge Distribution on a Conducting Shell

This is just a quick conceptual question. If you have a charge on the surface of a conductor, and the gaussian surface within that has a cavity containing a positive charge... and you move that charge off-center, does that affect the charge distribution on the surface of the conductor?
27. ### Basic Gauss's Law problem

Oh.. I guess I didn't realize that the area in Gauss's law was for enclosed charge only. Anyway,Thanks guys! I will definately refer back to this post when I work future problems! Hopefully, the more of these I work, the better my understanding of this subject will be. My main problem is that...
28. ### Basic Gauss's Law problem

Um. I guess radially outward? But how does that remove my need for rb in the expression? I should also have mentioned that I'm struggling with the material. My professor is absolutely no help. I've started skipping lecture just to hang out in the Physics helpdesk and work problems, since...
29. ### Basic Gauss's Law problem

Ah.. >< I'm almost 99% sure that the problem is me. But I'll ask anyway if nobody else on here can spot the mistake.
30. ### Basic Gauss's Law problem

Homework Statement We have solid ball of radius rb and charge density \rho. I need to find the magnitude of electric field E(r) at a distance r < rb from the center of the ball and express my answer in terms of \rho, r, rb, and \epsilon 0. Homework Equations Gauss's Law \int EA...