Tagged Questions
-1
votes
1answer
31 views
Can someone help with this hydrostatic force question? [closed]
A gate is in the form of a trapezoid 8 ft wide at the top, 5 ft wide at the bottom and is 3 ft high. If water reaches the top of the gate, what is the total hydrostatic force on the face of the gate?
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0
votes
0answers
60 views
Small oscillations [closed]
I am asked to consider a fixed homogeneous rod of length $2L$ and mass density $\rho$ It is centered around $O$. A particle with mass M is moving in the same plane. The attractive force between the ...
1
vote
1answer
295 views
Derivation of the self gravitational potential energy of a sphere
I have been searching on the Internet but have not found a derivation of the formula for the self gravitational potential energy of a sphere. Can someone show how to do this? I assume it involved 6 ...
0
votes
1answer
919 views
Calculating Moment Of Inertia
The problem I am working on is:
A uniform, thin, solid door has height 2.10 m, width 0.835 m, and mass 24.0 kg.
(a) Find its moment of inertia for rotation on its hinges.
(b) Is any ...
2
votes
3answers
211 views
How to get an integral formula for the flux time derivative
$$\frac{d}{dt}\int \limits_{A} \mathbf B d \mathbf A = \int \limits_{A} \left( \frac{\partial \mathbf B}{\partial t} + \mathbf v (\nabla \cdot \mathbf B ) + [\nabla \times [\mathbf v \times \mathbf B ...
0
votes
0answers
480 views
Create general equation of racing cars with head start [closed]
Cars A and B are racing each other along the same straight road in the following manner: Car A has a head start and is a distance $d_A$ beyond the starting line at $t=0$. The starting line is at ...
1
vote
1answer
113 views
Determine the flow and amplitude equation for thermal energy (with Del operator)
It is a question vector calculus and Maxwell's laws. I put it this way. Let's say, we are working in a $3$-Dimensional space ( e.g $x\cdot y\cdot z = 4\cdot3\cdot2$, a certain room/class of that size ...
1
vote
1answer
126 views
How to decompose a divergence operator
I am reading a paper, and see someone decompose a divergence operator as follows, could someone judge and see if it is correct?
$$\nabla \cdot {\bf{v}} = \left( {{\bf{n}} \cdot \nabla } \right){v_n} ...
2
votes
2answers
362 views
Galilean transformation of wave equation
I have this general wave equation:
\begin{equation}
\dfrac{\partial^2 \psi}{\partial x^2}+\dfrac{\partial^2 \psi}{\partial y^2}-\dfrac{1}{c^2}\dfrac{\partial^2 \psi}{\partial t^2}=0
\end{equation}
...
