All Questions
0
votes
0answers
3 views
Two transverse waves with equal frequencies f and amplitudes A move towards each other at velocity v. What is the resulting wave?
I came across this question in a SAT Physics Practice Test.
The possible answers are:
...
0
votes
1answer
5 views
Simplest derivation of Fourier transform for periodic functions (in crystal lattice)?
What is the simplest derivation of the following two well-known formulas that work for crystal lattice [1]:
$$
F[f(\mathbf{x})] \equiv \tilde f(\mathbf{G})
= {1\over\Omega_\mathrm{cell}} ...
1
vote
0answers
4 views
Estimating minimum energy with uncertainty principle
I'm currently trying to solve a problem that involves estimating the minimum energy of a particle in the potential:
$$
V(x) = \frac{-V_0a}{|{x}|}
$$
I'm quite confused about how to handle the ...
0
votes
0answers
8 views
Why does a particle fall in a straight line?
In Lagrangian Mechanics we choose the path of least action.
Given a uniform gravitational field, and a particle of finite mass; and fixing two points the start & end-point we consider all paths ...
0
votes
0answers
6 views
Pressure applied to flat plate
I have a question about the pressure placed on a plate of material X, how the force is distributed and what would be the material property that would determine its failure.
To simplify things ...
0
votes
0answers
6 views
Inelastic collision calculations
Assuming absolutely inelastic collision of two objects in vacuum without gravity. Objects not fixed in any axis and collision is made in 2d-space( omit methods of finding rotation axis ).
first ...
0
votes
1answer
9 views
Four protons are held on the corners of a square. What is their speed when they are far apart? [on hold]
This is a homework question, but I honestly have no idea how to go about it. Even the textbook says it's difficult, based on their disclaimer here:
"This is a challenging multi-step problem. Solve it ...
-1
votes
1answer
21 views
If nothing weighs something then doesn't that mean there is mass associated with spacetime?
Lawrence M. Krauss says, "If you removed all of the particles, all of the radiation,absolutely everything from space and all that remained was nothing that nothing would weigh something."
What ...
2
votes
2answers
18 views
What does it mean to be stationary?
I'm looking for a simple answer. What do we regard a stationary. Do we mean an object that is not moving noticeable from the viewers perspective because then a parked car would be considered ...
0
votes
0answers
8 views
What's the typical material used as a low-k ILD in semiconductors?
Semiconductor companies (namely IBM, Intel, TSMC and etc.) may use different low-k materials as inter-layer dielectric (ILD) in their fabrication process. I'm wondering what is the most typical one. ...
1
vote
1answer
18 views
Molecular formula of a compund
I have no idea on how to get information out of this one.
A compound contains only hydrogen and nitrogen. Nitrogen makes up for 87.4% of the mass. A sample of this have a density of 0.977 g/L at ...
5
votes
4answers
93 views
Why are rockets so big?
I'm curious why rockets are so big in their size. Since both the gravitational potential one need to overcome in order to put thing into orbit, and the chemical energy burned from the fuel, are ...
1
vote
0answers
11 views
How do they draw collision pictures in Atlas?
Is the picture below a simulation? How to they draw these pictures? The picture is from here.
3
votes
0answers
19 views
Effective mass of a black hole?
Suppose a black hole forms from a given mass of particles such as the core of a star going supernova. The black hole formed will have an effective mass due to the curvature of space time induced. Such ...
-1
votes
0answers
27 views
Question about angular momentum [on hold]
Two objects are attached to ropes that are attached to two wheels on a
common axle, as shown in Figure 9-60. The two wheels are attached
together so that they form a single rigid object. The ...
