Difficulty Definition and 261 Threads

I understand that a wave is most often oscillatory in character. That said, it does not have to be the case, for a wave is simply not the same as an oscillation: the former refers to a spatial pattern whereas the latter to a variation in time. We may think of a wave formed by an infinite number...

Please help me! I have been thinking on this problem A car of mass 450kg travels east at 4.5m/s, and collides with a 550kg truck infront of it traveling east at 3.7m/s. What are their velocity after the elastic collision. I know the energy formula and the momentum formula, and I know that...

A large tank of water has a hose connected to it. The tank is sealed at the top and has compressed air between the water surface and the top. When the water height h has the value 3.5 m , the absolute pressure p of the compressed air is 4.20 * 10^5 Pa. Assume that the air above the water expands...

Having difficulty finding the inverse laplace transform! Hello everyone, I am really stuck on finding the inverse Laplace transform for this: f(s)=\frac{5se^{-3s} - e^{-3s}}{s^{2}-4s+17} Heres my reasoning: I feel that I should rewrite the denominator in some kind of form such as (s-2)^2...

Recently took a test and got one of the lowest scores I've ever gotten...theres no tutor avaliable and the prof isn't avaliable either...I'm trying to figure out the correct answers and how and which equations to use for each problem. I always have difficulty interpreting the questions and...

Thank you for viewing this problem, hope u can help me. In one type of computer keyboard, each key holds a small metal plate that serves as one plate of a parallel-plate, air-filled capacitor. When the key is depressed, the plate separation decreases and the capacitance increases. Electronic...

Suppose the population of mosquitos in a certain area increases at a rate proportional to the current population... in the absense of other factors, the population doubles each week. There are 200,000 mosquitos in the area initially, and predators (birds, etc) eat 20,000 mosquitos /day...

This question is quite interesting: A uniform meter stick of mass M is pivoted on a hinge at one end and held horizontal by a spring with spring constant k attached at the other end. If the stick oscillates up and down slightly, what is it's frequency? The length of the stick is one meter...

Hi everybody The integral in question is the triple integral of x dV over the region E, where E is enclosed by the planes z=0, and z=x+y+3, and the cylinders x^2 + y^2 = 4 and x^2 + y^2 = 9. Well--- so far in cylindrical coordinates I know the r limits will be from 2 to 3 since the...

The Erdos-Straus Conjecture proposes that: For n >= 1, 4/n = 1/a + 1/b + 1/c, has postive integer solutions. n = 2k (evens) n = 4k+3 (odds) n = 4k+1 (odds) For 2k I have found the pattern --> if k >= 1, 4/2k = 1/2k + 1/2k + 1/k. This is simple, I know. I am having difficulty...

What is the technique behind lucid dreaming, and how difficult is it to accomplish?