0
votes
0answers
10 views

How to do This Torque problem? [closed]

The answer for the Question is 0.15kg. Is there any problem with the question because I cant seem to solve it. You can try working backwards.
1
vote
0answers
25 views

Euler Bernoulli beam

A simple model of the beam subjected to bending stresses is given by Euler-Bernoulli differential equation. Finite element discretization leads to a system of liniar equations.As discretization size ...
0
votes
0answers
28 views

Don't understand how this answer is arrived at; dynamic power

According to my notes the fomula for dynmaic energy is $\frac{1}{2}capacitive load \times voltage^2$ and formula for dynamic power is $\frac{1}{2}capaxitive load \times voltage^2 \times switching ...
1
vote
2answers
20 views

Getting the Amps from Watts, Amps and the voltage of a line

What amperage capacity should the supplied wired be rated for a refrigerated fixture which has a 208V power supply and the following loads? 4 Evaporator fan motor rated at 9W each 4 Evaporator fan ...
2
votes
0answers
53 views

Integral over orthogonal cylindrical harmonics

I am unsure how to solve an integral equation. As you know the orthogonality relation for cylindrical harmonics is: $$ \int_0^{2\pi}e^{in\phi'}e^{-im\phi'}d\phi'=2\pi\delta_{m,n}\ $$ The problem I ...
-1
votes
0answers
31 views

Mathematic Model Based newton Law [modelling math]

lower mathematical model By making use of Newton's laws, lower the mathematical model The following mechanical systems. Provide sufficient explanation of the phenomenon occurs. sorry for my bad ...
1
vote
2answers
25 views

Finding the magnitude of a vector product between two vectors?

Vector $\overrightarrow{A}$ has magnitude $11.0m$ and vector $\overrightarrow{B}$ has magnitude $16.0m$ . The scalar product $\overrightarrow{A}\bullet \overrightarrow{B}$ is $79.0m^2$. What is the ...
0
votes
3answers
54 views

Boxes on a slope [closed]

A box with friction slides down a slope and takes 2 times longer than a similar box with no friction takes to slide the same slope. What is $ \mu $ (the coefficient of friction)? I'm pretty lost. I ...
0
votes
1answer
25 views

Trying to understand free body diagram [closed]

Please consider the following image: Now I'm just trying to understand how exactly this thing is rotated...I'm looking at it exactly like on the image of the car...So the normal force is slightly ...
0
votes
1answer
46 views

Primitive of $(\frac{1}{\sqrt2}v_0e^{-kt})\sqrt{1+e^{-kt}} $

I have a watertank with a waterflow given by: $$v(t) = (\frac{1}{\sqrt2}v_0e^{-kt})\sqrt{1+e^{-kt}} $$ as a function of $t$ where $v_0$ and $k$ are positive constants. I'm trying to define the ...
0
votes
1answer
50 views

Suppose that $\int _0^1 f(x)v(x)=0$ for every $v \in C^{\infty}([0,1])$ for which $v'(0)=v(1/2)=0$. Show that $f(x)=0$ for all $x\in [0,1]$.

Suppose that $\int _0^1 f(x)v(x)=0$ for every $v \in C^{\infty}([0,1])$ for which $v'(0)=v(1/2)=0$. Show that $f(x)=0$ for all $x\in [0,1]$.Suggestion: take u to be the suitable cut off version of ...
2
votes
0answers
35 views

Fock Subspaces and Weight Vectors

I've got an assignment due in a few hours, and I'm at a complete loss as to how to even start it, really. I haven't encountered any Dirac notation before, so I'm having a lot of trouble attempting the ...
0
votes
0answers
39 views

Equations of motion for a block

I am looking for a very simplified derivation of the equations of motion (rotational and translational) for a block with a body fixed frame. I need to compare the EOMs for a system when the center ...
1
vote
1answer
34 views

Compute the curl

Given that $\vec{\nabla}.{\vec{m}}=0$, and the vectors be in $\mathbb{R}^3$ I am trying to show that $$\vec{\nabla}\times \frac{r^2}{2}\vec{r}\times\vec{m}=(\vec{m}.\vec{r})\vec{r}-2r^2\vec{m}$$ I ...
0
votes
1answer
33 views

Periodicity on System of Equations

$$ y(t) = \begin{bmatrix} cos\sqrt\omega & -sin\sqrt3\omega & 0 & 0 \\ sin\sqrt3\omega & cos\sqrt3\omega & 0 & 0 \\ 0 & 0 & cos\omega & -sin\omega \\ 0 & 0 ...
3
votes
1answer
124 views

How do I calculate the following? (with answers)

Would anyone be able to help me calculate the following questions? I have the answers, I just want to understand the process. If you are able to give me any feedback, would you be able to write your ...
12
votes
1answer
191 views

Problem in Hamiltonian system

Not sure if this is too much physics to be here... Consider $$H:\mathbb{R}^{2N+1}\rightarrow\mathbb{R}$$ of class $C^2$, let $H(x,y,z)$ such that $x\in\mathbb{R}^N$, $y\in\mathbb{R}^N$ and ...
1
vote
1answer
50 views

What does this mean: Symmetry of the KDV generated by a vector field

What is a symmetry of the KDV $$\frac{\partial u}{\partial t}=6u\frac{\partial u}{\partial x}-\frac{\partial^3 u}{\partial x^3}$$ generated by $$V=A(t,x,u)\frac{\partial }{\partial ...
1
vote
1answer
68 views

Is the following differentiating under the integral sign correct?

Suppose $$\frac{\delta f[u]}{\delta u(x)}\equiv \frac{\partial f}{\partial u}-\frac{\partial }{\partial x}\frac{\partial f}{\partial u_x}+\left(\frac{\partial }{\partial x}\right)^2\frac{\partial ...
0
votes
0answers
71 views

Geodesic equation for a 2D manifold

I am having trouble understanding how the following statement (taken from some old notes) is true: For a 2D manifold such that $$ds^2=\frac{1}{u^2}(-du^2+dv^2)$$ If we assume that $$\dot x^a\dot ...
1
vote
1answer
260 views

How to solve a tensor differential equation?

Essentially, How does one solve the tensorial differential equation $$\frac{dx^a}{d\tau}=A^a{}_bx^b$$ where $x^a$ is a 4-vector and $A^a{}_b$ is a $(1,1)$ tensor. The original Problem How does ...
1
vote
1answer
48 views

Sketch the waves described by $y=(0.8\text{ meters})\sin[0.628(x-vt)]$

Ocean waves with a crest to crest distance of $10$ meters can be described by the wave function $$y=(0.8\text{ meters})\sin[0.628(x-vt)]$$ where $v=1.2 \text{ meters/s}$. a) Sketch $y$ at ...
2
votes
0answers
63 views

Laplacian of a function implies the function cannot have max or min.

If $\bigtriangledown^2f = 0 $ in some region in the space, then $f$ cannot have maximum or minimum on that region. My approach was to assume $f$ has a maximum and then use the second derivative test ...
0
votes
1answer
136 views

Find the parametric equation of the path of an object going at a speed x , with an orientation vector at time t and point p

$$ x = 1/2, v[2,−2], t = 3, P(1, 2)$$ x = speed, v = orientation, t = time, p is a point. I tried this : $$((2, -2) - (1,2)) \sqrt{1^2 + 4^2} $$ I got my <1,4> from $(2-1, 2-(-2))$ , which is my ...
3
votes
1answer
1k views

Frobenius Method to solve $x(1 - x)y'' - 3xy' - y = 0$

So, Im trying to self-learn method of frobenius, and I would like to ask if someone can explain to me how can we solve the following DE about $ x = 0$ using this method. $$ x(1 - x)y'' - 3xy' - y = 0 ...
1
vote
1answer
69 views

bundle isomorphism

Let $M$ be a manifold and let $U_{\alpha}$ and $U_{\beta}$ be coordinate charts with coordinates $x^{\alpha}$ and $x^{\beta}$, respectively. How to show that $f_{\alpha} : ...
1
vote
1answer
52 views

How to linearize $V=V_w+(V_0-V_w)e^{-kt}$

I have a physics homework and I was asked to transform $v=v_w+(v_0-v_w)e^{-kt}$ into a linear equation to be graphed. ($v_w$ is one variable that is constant and $k$ is constant.) $v$ is velocity ...
3
votes
3answers
166 views

How to conclude this solution is periodic?

I've met the following problem in finishing my argument. The expression I ended with is $$\frac{\mathrm d}{\mathrm d\xi}U(\xi)=\pm\sqrt{C_1-\frac{U^4(\xi)}{2}},$$ with $U:\mathbb R\to\mathbb R$ and ...