Recent content by eil2001

so, would it not work if I assume that the +z-axis is OUT of the page?

Ok, so let me just get this straight. Let's say the charge is moving along the +x-axis, so directly to the right and B is out in the +z-direction, then vXB gives an F down, but b/c the q is negative, F really goes up along the +y-axis. Now, b/c v is really 50 degrees CCW from the +x-axis, you...

Thanks...ok, but so then why is the F 40 degrees CW from the +x-axis? If instead of pointing in the 4th quadrant, it points in the 2nd quadrant now b/c q is negative, then shouldn't the answer be 40 degrees CW from the -x-axis? Thanks.

Hi, I have a question: If there is a negative charge moving w/a velocity that is 50 degrees counter-clockwise from the +x-axis and a B field in the +z direction, I get that the magnitude of the Magnetic Force=(abs. val of q)(abs. val of v)(abs. val of B)sin(theta), where theta=angle b/t v and B...

E is the emf.

I have a homework question about a potentiometer. There is a resistor between a and b that is a uniform wire of length l, with a sliding contact c at a distance x from b. An unknown potential difference V is measured by sliding the contact until the galvonometer G reads zero. I need to show...

Here's a question from my textbook: Two positive point charges, each of magnitude q, are located on the y-axis at points y=+a and y=-a. A third positive charge of the same magnitude is located at some point on the x-axis. (a) What is the net force exerted on the third charge when it is at the...

Thanks, but why should q_1 and q_2 have the same magnitude? And then how do you go from "q" to the number of electrons?

Here's a question from my textbook: Two copper spheres, each having a mass of .4 kg, are separated by 2 m. (a) How many electrons does each sphere contain? The atomic mass of copper is 63.5 g/mol, and its atomic number is 29. (b) How many electrons would have to be removed from one sphere...

At the top of the snowball, isn't there kinetic energy, too, b/c the problem says that the skier starts with a small initial velocity? Or, is that "small" supposed to mean negligible? Also, how do I find the height at which the skier leaves the snowball? I feel like it's something w/angles...

Hi, thanks for your help, but when I do -mgdsin(30), I get -(28 lb)(32 ft/s^2)(15 ft)sin(30) = -6,720 ft-lb, not the -210 ft-lb that the book says I should get. Any ideas?

Ok, here's the question: A skier starts at the top of a very large frictionless spherical snowball, with a very small initial velocity, and skis straight down the side. At what point does she lose contact with the snowball and fly off at a tangent? That is, at the instant when she loses...

I have this question: A 28 lb suitcase is pulled up a frictionless plane inclined at 30 degrees to the horizontal by a force P with a magnitude of 18 lb and acting parallel to the plane. If the suitcase travels 15 ft along the incline, calculate: (a) the work done on the suitcase by the...