# All Questions

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### Delta wing flow patterns (straight and yawing)

I was wondering the differences between fluid patterns and their consequences when a delta wing is straight and yawed slightly.
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### Can we deviate a bullet from its target? Did anybody try this?

Can we deviate a bullet from its target? Means by applying any strong field at the target? Is there any technique so far like this!
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### What are the “other” Hadamard matrices?

The Pauli matrices $$X = \begin{pmatrix}0&1\\1&0\end{pmatrix}, Y=\begin{pmatrix}0&-i\\i &0\end{pmatrix},\,\text{and}\, Z=\begin{pmatrix}1&0\\0&-1\end{pmatrix}$$ can be used ...
100 views

### What does traveling close to speed of light mean?

This has been bugging me for a while. We all know in relativity that if you travel close to speed of light, all sorts of crazy things happen. But what does it mean to travel close to speed of light? ...
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### 2 spheres both negative or positive [closed]

Two small charged metal spheres A and B are situated in a vacuum. The distance between the centres of the spheres is 12.0 cm, as shown in Fig. 4.1. The charge on each sphere may be assumed to be a ...
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### Are the laws of physics bound by the same performance bounds algorithms are bound by?

Consider the problem of finding the convex hull for $n$ points on a plane. No constant time algorithms exist to solve it. Now say you represent the points as poles of equal height that you hammer ...
1k views

### Intuition on positive-operator valued measures (POVM)

I'm having a little trouble understanding what positive-operator valued measure (POVM) are- in particular why/how they are non-negative. For instance, if they just represent measurements, what about ...
144 views

### Uses of Static Electricity

Is it possible to store static electricity in any type of battery and can they be used in electric appliances(light,bulbs mainly)?
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### Is a gapless system always conducting and a gapped system insulating?

In an answer to this question, @user566 mentioned that there is a qualitative difference between gapped and gapless systems; that gapless systems are conducting and gapped system are insulating. Is ...
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### Relative time/space - Two clock thought experiment [duplicate]

Please pardon my english. Here is my simple thought experiment. ...
82 views

### Hydrogen bond and van der Waals bond

Just now I am studying about hydrogen bond and van der waals bond. I understand and able to differentiate between them but thinking of the similarities, do they have any?
98 views

### Determine eigeinvalue and eigenvector of two operators R and L [closed]

Question: Let H be a Hilbert space with countable-infinite orthonormal basis ${|n>}_{n \in N}$. The two operators R and L on H are defined by their action on the basis elements \begin{align} ...
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### How can there be current if all paths have same potential difference

I am learning about circuit analysis now, but there is something that I can't wrap my head around. Imagine this simple circuit: ...
2k views

### How can energy be useful when it is 'abstract'?

The topic which haunted me for two years until I gave up on it. But now I am doing engineering and this topic suddenly popped out of my textbook from nowhere. I seriously need to understand this topic ...
465 views

### Why in series combination of circuit has same amount of current flow in every conductor? [duplicate]

Why in series combination of circuit has same amount of current flow in every conductor? Whereas in parallel combination the amount of voltage is same?
122 views

### Clarification about Bragg's law explanation

The Wikipedia has this illustration of Bragg's law and then says The two separate waves will arrive at a point with the same phase, and hence undergo constructive interference, if and only if ...
114 views

### Standing waves on a compound string

I've been having some difficulties in understanding standing waves. The questions that I have are as follows: 1) Suppose I have a compound string, made up of two strings. What is the correct way to ...