Recent content by lu6cifer

My book says that positive charges drift in the direction of electric field, and negative charges drift in the direction opposite of electric fields But wouldn't that depend on if the electric field was generated from a positive or negative charge? How can they just make a generalization like...

A nonuniform linear charge distribution given by λ = bx, where b is a constant, is located along an x-axis from x = 0 to x = 0.50 m. Suppose that b = 25 nC/m2 and V = 0 at infinity. (b) What is the electric potential at the point y = 0.30 m on the y axis? E = kq/r^2 V = -EdSince there's no...

Ring of Charge--how to maximize the Electric Field A thin nonconducting rod with a uniform distribution of positive charge Q is bent into a circle of radius R. The central perpendicular axis through the ring is a z-axis, with the origin at the center of the ring. (c) In terms of R, at...

Let's say there's a lab where one hangs weights off a spring, and graphs the length and weight to find the spring constant. Graphs have the independent variable--weight in this case--on the x axis, and the dependent variable--length--on the y axis. So, by that method, the graph should be...

I know that moving things is a lot easier with wheels, and I suspect it has something to do with the friction on the wheels versus the friction on just a regular sliding object. But how do you prove, with the laws and equations of physics, that it takes less force to move something when there...

A projectile is shot directly away from Earth's surface. Neglect the rotation of Earth. (a) As a multiple of Earth's radius RE, what is the radial distance a projectile reaches if its initial speed is one-third of the escape speed from Earth? (b) As a multiple of Earth's radius RE, what is...

Thanks---Your hints worked!

Two satellites, A and B, both of mass m = 110 kg, move in the same circular orbit of radius r = 7.45 x 10^6 m around Earth but in opposite senses of rotation and therefore on a collision course. (a) What is the total mechanical energy EA + EB of the two satellites + Earth system before the...

Spring Energy--a block slides down a frictionless incline plane A block of mass m = 13 kg is released from rest on a frictionless incline angled of angle θ = 30°. Below the block is a spring that can be compressed 2.0 cm by a force of 270 N. The block momentarily stops when it compresses the...

I realize that they're opposites, meaning one is a positive value and the other is negative, but how is that determined? That is, how would you derive that based on the laws of physics?

No, I get the semantics part, that in one case it's work done on a spring and in another it's work that's being done by the spring, but what's the physics explanation for why the x's are positioned where they are?

Why is it that the equation for work done to stretch a spring is W = 1/2k(x22-x12) while the work done by a spring on an object is W = 1/2k(x12-x22) ? That is, how come it's x22-x12 for the first case, and x12-x22 for the second?

1.Quick question: a 12kg mass is on a 30 degree incline where the coefficient of static friction is 0.8. What is the friction force exerted on the mass? 2. F = ma, f = uN 3. I got around 83 N for this. All I did was multiply the coefficient of friction by normal force, which...

A spring with a pointer attached is hanging next to a scale marked in millimeters. Three different packages are hung from the spring. W1 is 110 N, and hangs 40mm from the spring, W2 is 240N and hangs 60mm from the spring W3 is x N and hangs 30 mm from the springWhat mark on the scale will the...

So, when the centripetal force, ie, the mv2/r part of the equation is less than W, that means that the normal force is directed upwards, and if it's more than W, the normal force is directed downwards? And, what would an upward normal force mean as opposed to a downward one if this situation...