Recent content by davidY

thanks. by the way, would it be the fringing effects of the electric fields that cause the force? (as the non fringing electric field would be pointing in the direction of one plate to another)

suppose you had a capacator and a free to move dialetric, which was outside of it, and you attatch a voltage to the capacator. the dialetric will move in. however, does anybody know what force and where the force is that causes the dialetric to move in?

1. assume that the steady state 2. get a thin slice of tube 3. since steady state: heat enter=heat exit 4. this means H is constant over all x 5. our equation: H=-kA(dT/dx) H=-k*pi*r^2*(dT/dx) 7. well, pi is constant over all x 8. well, r is not constant over all x 9. good luck...

for hollow sphere: well, the e field is constant over the surface of the sphere. so all you have to do is to use a polar integration with two cosines in the function. to find the component in the away from centre direction. because by symmetry the force is outwards radially. for solid...

if you are good at maths, here is one option: use gauss laws to find equation E field at every point integrate the F=Eq over the entire sphere long integration, not really that hard if it is a hollow sphere. seems quite hard if it is solid, not sure (i hope this method works)

if you are confused about that i think that he used: dsin(theta)=m*lambda and for small theta sin(theta)=tan(theta) and in this case, tan(theta)=Size projected on screen/distance to screen

try this: let a^n=1 =cis(0+2k*pi) for k=integer by de-moivres a=cis(2(k/n)*pi) there you have the roots, the bth root is probably k=b

yeah, i want the total velocity of the little block. however here are the conservation equations: Energy Initial = mgh Energy Final = 1/2 M(velocity of wedge)^2 + 1/2m(velocity in horizontal direction of little block)^2 + 1/2 m(velocity in vertical direction of little block)^2 P Inital =...

simple question: a movable block on a movable wedge on some frictionless ground. we know all masses, angles, and there is no friction. the block starts on the wedge at some height h, and slides down the wedge. the block moves forwards, and the wedge moves backwards. what is the velocity of the...