PhoenixFire
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Questions Asked

PhoenixFire:
Group Title
Determine what the speed v of the bullet should be such that the rod swings exactly 90 degrees from it's initial equilibrium position. Expre…
 updated one month ago
 21 replies
 1 Medal
Mathematics

PhoenixFire:
Group Title
If a uniform rod fixed at one end hangs in earth gravitational field is given an initial angular velocity w. Find how far it rotates, \(\the…
 updated one month ago
 40 replies
 1 Medal
Mathematics

PhoenixFire:
Group Title
Let H be the set of all vectors of the form (a5b, b2a,b,a), where a and b are arbitrary real scalars. Show that H is a subspace of \(\math…
 updated one month ago
 12 replies
 1 Medal
Mathematics

PhoenixFire:
Group Title
Sequence:
\(x_1=1\), recursive definition: \(x_{n+1}=\sqrt{1+x_n} \) for all n>=1
…
 updated one month ago
 11 replies
 2 Medals
Mathematics

PhoenixFire:
Group Title
\[\lim _{ a\rightarrow 0^+ }{ \frac{1}{a^a} } \]
I know the answer is 1, but how do you approach this question?
…
 updated one month ago
 7 replies
 2 Medals
Mathematics

PhoenixFire:
Group Title
How would I show that the error function erf is strictly increasing?
I got the Taylor series:
…
 updated one month ago
 11 replies
 3 Medals
Mathematics

PhoenixFire:
Group Title
Thermodynamics:
A column of dry air with crosssectional area \(1m^2\) with surface pressure of 1atm.
Over a few hours it gains 2MJ of en…
 updated one month ago
 No Medals Yet
Mathematics

PhoenixFire:
Group Title
How do you row reduce this? No matter what I try I get ugly numbers.
\[ \left[\begin{matrix} 22 & 16 & 2 \\ 16 & 12 & 0 \end{matrix}\rig…
 updated 2 months ago
 2 replies
 2 Medals
Mathematics

PhoenixFire:
Group Title
Given the equation of damped shm \[\frac{d^2x}{dt^2} +B\frac{dx}{dt}+Cx=0\]
And the solution \[x=Ae^{\frac{t}{T}} cos(wt+d)\]
Where T is …
 updated 3 months ago
 6 replies
 2 Medals
Mathematics

PhoenixFire:
Group Title
Particle moving in spiral where decreasing radius r is given by \(r=bct\) and the angular velocity increases \(w=kt\) . Where b,c,k are con…
 updated 3 months ago
 No Medals Yet
Mathematics

PhoenixFire:
Group Title
A free electron in an oscillating field experiences a force \(\mathbf{F}=e\mathbf {E}(t)\), where \(\mathbf {E}(t)=\mathbf {E_0}sin(wt)\) a…
 updated 3 months ago
 5 replies
 2 Medals
Mathematics

PhoenixFire:
Group Title
Calculating errors.
if uncertainty in x = 5% and \(y=\frac{1}{100} x\) and \(z=x+y\) calculate the error in \(z\) when the uncertainty in y…
 updated 4 months ago
 No Medals Yet
Mathematics

PhoenixFire:
Group Title
Calculating errors.
if uncertainty in x = 5% and \(y=\frac{1}{100} x\) and \(z=x+y\) calculate the error in \(z\) when the uncertainty in y…
 updated 4 months ago
 No Medals Yet
Mathematics

PhoenixFire:
Group Title
\[F(x)=\int _{ 1 }^{ ln(x^{ 2 }+e) }{ sin(e^{ t }) } dt\]
Find F'(x).
Not sure how to do this, I understand from the Fundamental Theorem o…
 updated 8 months ago
 4 replies
 1 Medal
Mathematics

PhoenixFire:
Group Title
If everyone on the earth lined up around the equator and started running east at 2.5 m/s (EDIT: velocity is relative to surface of the Eart…
 updated 8 months ago
 52 replies
 3 Medals
Mathematics

PhoenixFire:
Group Title
Calculating the Spring Constant.
A bungy cord 20m in length has a 85kg ball attached to it. The ball is dropped off a 45m building and s…
 updated 8 months ago
 No Medals Yet
Mathematics

PhoenixFire:
Group Title
Pressure variation of helium gas in equilibrium is given by \[\triangle P=2.9x{ 10 }^{ 5 }cos(6.2x3000t)\] where x and t have units m and …
 updated 9 months ago
 No Medals Yet
Mathematics

PhoenixFire:
Group Title
\[\int_{e^1}^{e} {\frac{1}{t(1+\left  ln(t) \right )} dt}\]
Can anyone guide me on starting this integral? I've tried numerous times but…
 updated 10 months ago
 10 replies
 No Medals Yet
Mathematics

PhoenixFire:
Group Title
An inductor is connected to an AC power supply with maximum output voltage \(V\) at frequency \(f\).
What inductance is required to keep th…
 updated 11 months ago
 6 replies
 1 Medal
Mathematics

PhoenixFire:
Group Title
Simple algebra that I apparently cannot do... Can anyone help here? Simplify the following:
\[{x\frac{1}{x}}={y\frac{1}{y}}\]
…
 updated 11 months ago
 10 replies
 1 Medal
Mathematics

PhoenixFire:
Group Title
A uniform rod of length 'L' sits at rest vertically. The base of the rod is connected to a frictionless pivot.
It then falls over under th…
 updated 11 months ago
 1 reply
 No Medals Yet
Mathematics

PhoenixFire:
Group Title
Net force between three long wires (undefined length) must equal zero.
Wire 1: Current going Up \(I_1\)
Wire 2: Current going Down \(I_2\)…
 updated 11 months ago
 31 replies
 2 Medals
Mathematics

PhoenixFire:
Group Title
Funtion Definitions
*Need editor hold on*
 updated 11 months ago
 7 replies
 2 Medals
Mathematics

PhoenixFire:
Group Title
Confused here...
\[F=mg=m \frac{GM}{r^2}\]
We know 'g' is an acceleration which is \(ms^{2}\)…
 updated one year ago
 4 replies
 2 Medals
Mathematics

PhoenixFire:
Group Title
Evaluate the surface integral:
\[\iint _{ S }^{ }{ \vec { F } \cdot \vec { dS } }\] Vector field: \[\vec { F } =<y,zy,x>\]
Surface 'S'…
 updated one year ago
 2 replies
 No Medals Yet
Mathematics

PhoenixFire:
Group Title
Evaluate the surface integral:
\[\iint _{ S }^{ }{ z } dS\]
Where S is the surface \(x=y+3z^2\) for \(0\le y\le 1\) and \(0\le z\le 1\)
 updated one year ago
 5 replies
 2 Medals
Mathematics

PhoenixFire:
Group Title
Factoring a cubic polynomial.
\[x^3108x^2+3564x34992\]
…
 updated one year ago
 14 replies
 1 Medal
Mathematics

PhoenixFire:
Group Title
Double Integrals
Find the volume of the solid \(z=(x^2 + y^2)1\) between the two plates z=0 and z=1
…
 updated one year ago
 43 replies
 No Medals Yet
Mathematics

PhoenixFire:
Group Title
Two point Charges each with a charge of +10nC sit at (0,0,0) and (1,2,1). Find the Electric Field E at point (4,4,4).
Give me a second to…
 updated one year ago
 3 replies
 No Medals Yet
Mathematics

PhoenixFire:
Group Title
How do I use Gauss' Law to show that the electric field of any point inside (r<R ) the hollow sphere is 0?
 updated one year ago
 2 replies
 1 Medal
Mathematics
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