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### Can anyone suggest which piechoelectric material is the cheapest

can anyone suggest which piechoelectric material is the cheapest. Or maybe there are similar materials that have the ability to respond to pressure? Please excuse my english))
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### Question about a problem involving electrostatics

I need help with the following problem: An uncharged ball of mass m = 1 g hangs on a thin inextensible thread of length L = 10 cm in air. A second ball with charge Q = 2 · 10−8 C is brought into the ...
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### When deriving the analytic representation of Fock states , why doesn't the $\hat{P}$ operator act on the ground state?

Starting with \begin{align*} |n \rangle=\frac{1}{\sqrt{n!}}(\hat{a}^{\dagger})^{n}|0\rangle \end{align*} and \begin{equation} \psi_{0}(x)=\left(\frac{m\omega}{\pi\hbar}\right) ^{\frac{1}{4}}\...
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### Relation between acceleration vectors from ground frame and a frame rotating relative to ground [closed]

How do we find out the relation between acceleration vectors from ground frame and a frame rotating relative to ground. I have been trying it for hours with little to no success so any help would be ...
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### How can velocity of water remain constant for a vertical cylindrical tube?

I have got a question in the Physics textbook which is as follows: Water enters through end A with speed v1 and leaves through end B with speed v2 of a cylindrical tube AB. The tube is always ...
1 vote
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### Four vectors and coordinates

Hartle, gravity. Chapter 5 A four-vector is defined as a directed line segment in four-dimensional flat spacetime in the same way as a three-dimensional vector (to be called a three-vector in this ...
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### Why electric field and magnetic field are in phase in electromagnetic waves?

I can understand in mathematics but could you please explain it's physical significance (such as from the energy perspective)?
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