Saturday
February 6, 2016

Posts by Charlie

Total # Posts: 439

Physics capacitance
Thank you very much.
May 7, 2009

Physics capacitance
I know that to solve: f=1 over 2 pi sqrt LC for C, I have to use C= 1 over L(2 pi f)^2 Can someone take me through the rearranging please. Thanks.
May 7, 2009

Thermodynamics
Thank you for giving such a detailed answer.
May 3, 2009

Thermodynamics
Would someone explain entropy in simple terms please. Thanks.
May 3, 2009

physics :thinking check please
HELP! Time running out! Thanks
April 30, 2009

physics :thinking check please
I think that: psi= A sin kx; is a solution to Schrodinger's time independent eqn for a particle confined: a) within an infinite pot well, and b) within the walls of a finite well;but psi= B exp(-kx) would only be a solution for outside the walls of a finite well. Am I ...
April 30, 2009

Physics
If energy is 1/2 mv^2; and m and v are always positive.... How come the ground state energy of Hydrogen is a minus value? Charlie
April 14, 2009

physics
Thanks, CI
April 11, 2009

physics
If I had made it conditional that the electron was orbiting at a constant radius, would it then be correct; and would it also be accurate in 'ordinary' situations, eg spinning a stone around on a string?
April 11, 2009

physics
I've just read that the centripetal force on an electron is mv^2/r; and that this is also equal to the electrostatic force pulling the electron toward the nucleus. Does mv^2/r hold good in all Newtonian siuations as a formula for centripetal force acting on a body? Thanks
April 11, 2009

physics: relativity
I think I can rearrange the Lorentz contraction equation, solving for v using: v=sqrt[1-(L/Lo)^2] x c^2 Would someone check my thinking please? Thanks
March 30, 2009

math
The answer was incorrect and that is why I am asking again Mr. Parsley
March 27, 2009

math
In the number 268,743 how many times greater than the 3 is the 6?
March 27, 2009

math
write the next four letters in this sequence A B Z Y C D
March 27, 2009

Physics
Reposted under Physics... I've tried for hours to solve for v, but can't get the rearranging right. I'm using L= Lo sqrt 1- v^2/c^2 Can anyone suggest the first couple of steps? I can get the answer by the way, by substituting values 'til I get the contracted ...
March 27, 2009

lorentz contraction
I've tried for hours to solve for v, but can't get the rearranging right. I'm using L= Lo sqrt 1- v^2/c^2 Can anyone suggest the first couple of steps? I can get the answer by the way, by substituting values 'til I get the contracted length. Original and final ...
March 27, 2009

math
what is the answer to. Write the next 4 letters in this sequence: A,B,Z,Y,C,D
March 26, 2009

math
In the number 268,743 how many times greater than the 3 is the 6
March 26, 2009

lenses, still stuck!
Thanks drwls, for that. However, the question acually asks me 2 things: the total M; and to find the length of the microscope! The questioner clearly thinks I have enough info to go on from what I've given above. Charlie
March 24, 2009

lenses, still stuck!
I need to calculate the magnification, m of an objective lens, so I can then x it by the eyepiece value for M to get the total magnification. I need v/u (v is dist from lens to image; u is dist of object to lens) I'm using 1/f = 1/v+1/u rearranged for 1/v. That's: 1/v...
March 24, 2009

math
Ms Writeacher my math work book which is a fifth grader Harcourt Math Practice Workbook does not say what Tues so my mon think it has to be the same Tues in the week of the other days
March 9, 2009

math
the response from Ms writeacher did not show the answer
March 9, 2009

problem solving
kirk grew a crystal in science class. On monday it was 13/16 inch tall. it had grown 1/4 inch bet friday and monday. It had grown 1/2 inch between Tues and Fri. How tall was Kirk'a crystal on Tues?
March 9, 2009

math
Thanks Jessica
March 9, 2009

math
what is the value of 4 in 0.045
March 9, 2009

Physics
Can the magnitude of a magnetic field be negative? If we consider an electron in a mag field, using r=mv/qB, the negative charge on the electron gives a negative answer. Do I drop the minus sign?
February 25, 2009

Math/Physics
In a 9V circuit, all the resistors are 20 or 40 kilo Ohms. Convention says that calcs should therefore be quoted to 1 sig fig, since the volts are the least accuracy. 2 seems better though. Any ideas?
February 23, 2009

Sig Figs
In a 9V circuit, all the resistors are 20 or 40 kilo Ohms. Convention says that calcs should therefore be quoted to 1 sig fig, since the volts are the least accuracy. 2 seems better though. Any ideas?
February 22, 2009

Physics
Thanks (I'm not much wiser!), but what's ve as in 'between ve and zero' please?
February 17, 2009

Physics
(1) 2 particles of equal mass are fixed at X=0 and another +ve point on the x axis. No other grav influences are in the system. (they can be ignored) I have to derive an expression for Vgrav at a general position x, on the x axis. I believe this is related to V=-GM/r, but can...
February 17, 2009

gravitational potential
(1) 2 particles of equal mass are fixed at X=0 and another +ve point on the x axis. No other grav influences are in the system. (they can be ignored) I have to derive an expression for Vgrav at a general position x, on the x axis. I believe this is related to V=-GM/r, but can...
February 17, 2009

biology
can i get some help here please? much appreciated.
February 16, 2009

biology
i'm doing the same problem and confused about the same thing, so i'll just wait for the answer
February 16, 2009

Physics, Thinking check please
Very kind drwls, thanks a lot. Charlie
February 16, 2009

Physics, Thinking check please
A 9v circuit charges a capacitor to steady state. Then the switch is opened. All resistance units in kilo-ohms: 2 rsistors, 20 and 40kO in parallel with a single 20 kO resistor. Total R is 3.33x10^4 Ohms. Am I close? If so, and the time constant is 1.6x10^-3 seconds, then is ...
February 16, 2009

physics: Electricity/Resistance
I forgot to say "take the reciprocal". Does that make more sense?
February 16, 2009

physics: Electricity/Resistance
I get it. My text shows your formula, but recommends 1/R= 1/R1+1/R2 etc as easier! I'm with you. If the numbers match, is my thinking ok?
February 16, 2009

physics: Electricity/Resistance
If I have a 9V circuit, with: 2 resistors in parallel; followed by: 2 single resistors in series; and I calculate the effective R of the parallel pair (using 1/R=1/R1+1/R2); can i then add this value to the series resistors to get a total for the circuit? As in: (1/R=1/R1+1/R2...
February 16, 2009

Physics
that's 3x10^6, not -6
February 7, 2009

Physics
I need to calculate the closest two parallel plates can get before they spark I have the voltage, and will use E=V/dist (rearranged) to get the distance. I THINK the field strength value I should use is 3x10^-6 Vm^-1. No other info is given in the question, so am i close? Thanks
February 7, 2009

Physics
I'm stumped: So bringing it back to the top. Hope that's ok! 2 charges, Q1 and Q2, equal magnitude, but different signs (not assigned) lie on a line, x axis, a known distance apart. Segment p-q lies centrally on the line, distance apart is known. An electron is ...
February 4, 2009

physics fields and charges
Sorry, the field is said to be constant around the central segment pq, which is only 10 cm long.
February 3, 2009

physics fields and charges
I'm stumped: 2 charges, Q1 and Q2, equal magnitude, but different signs (not assigned) lie on a line, x axis, a known distance apart. Segment pq lies centrally on the line, distance apart is known. An electron is released at p from rest, and passes q at a given time later...
February 3, 2009

physics, fluids
Thanks, all 3.
January 24, 2009

physics, fluids
It's given that it is an ideal fluid, and I'm asked to explain the significance of the expressions. I se a relationship with 1/2mv squared and mgh, but can't explain it clearly.
January 24, 2009

physics, fluids
would I be correct if I explained the 3 expressions in Bernoulli's equation as representing: P is the pressure 1/2*rho*v squared is the kinetic energy rho*g*h is the gravitational kinetic energy. Or is it more complicate than that. Thanks
January 24, 2009

Human Anatomy
What are the bony landmarks of the abdominopelvic cavity?
January 13, 2009

French
My french teacher has asked us too gather us questions to ask our pen pals on a live link up. (webcam to each other) but, i cannot think of anything to ask her. Please help and give me some ideas ? Charlie. x (:
January 12, 2009

Atomic Mass
Hi if I divide a molar mass of an element by Avogadro's number (63022X10^23) will i have the mass of 1 atom of the element? Thanks
January 7, 2009

physics
Spotted! Thanks Dr Bob.
January 7, 2009

physics
Hi if I divide a molar mass of an element by Avogadro's number (63022X10^23) will i have the mass of 1 atom of the element? Thanks
January 7, 2009

Physics ideal gases
Thank you both.
January 3, 2009

Physics ideal gases
If 2 samples of nitrogen (different PVTs) are separated by a conductive barrier, they will eventually achieve equilibrium, I believe. Am I right to assume that the final T and P at equilibrium in this case would be the SAME T and P if the barrier was highly insulated, then ...
January 3, 2009

Physics ideal gases
Thanks Damon, I realise I didn't tell you what i'm asked to do! I note your point about the start point for the equation. Thanks
January 2, 2009

Physics ideal gases
Would someone check my thinking please. PVT of an ideal gas (nitrogen) are all given. I've used PV=nRT rearranged to get the number of moles. Then, U= 3/2nRT to get the internal energy of the sample. Am I on the right track? Thanks.
January 2, 2009

Physics
For a child's swing in lightly damped SHM, I am given the time period and a value for g; (as well as the mass.) with just these, can i rearrange the equation: T (4s)= 2pi times sqrt l/g to calculate the length of the swing? I believe i have (3.98m), but the question says ...
December 16, 2008

Physics
For a child's swing in lightly damped SHM, I am given the time period and a value for g; (as well as the mass.) with just these, can i rearrange the equation: T (4s)= 2pi times sqrt l/g to calculate the length of the swing? I believe i have (3.98m), but the question says ...
December 16, 2008

Physics (checking my thinking)
Thanks both, for the answers.
December 14, 2008

Physics (checking my thinking)
Yes, it's zero. That seems to make the second term (m2u2) zero, but I still get what i think is the correct answer. What should be my next approach?
December 14, 2008

Physics (checking my thinking)
2 spheres, of unequal masses, hang on strings and are touching. Sphere a is pulled back to the left, string taught, and released, hitting sphere B at a known velocity. Sphere B's post impact velocity is known, and to the right. i have to find A's post collision ...
December 14, 2008

physics
How large a pressure increase (in ATM) must be applied to water if it is to be compressed in volume by 1%? The bulk modulus of water is 2 ~ 10^9 N/m^2 and 1 ATM = 10^5 N/m^2 I think that it is P = bulk modulus * 0.01 because 1/100 = 0.01, which is 1% of a volume. B = &#...
December 10, 2008

Physics
why 0.001? 1/100 is 0.01. I thought that was 1 %. Also is that pressure minus (-) or pressure (equals)?
December 10, 2008

Physics
How large a pressure increase (in ATM) must be applied to water if it is to be compressed in volume by 1%? The bulk modulus of water is 2 × 109 N/m2 and 1 ATM = 105 N/m2
December 10, 2008

Physics
Thanks very much, I appreciate it.
December 5, 2008

Physics
A pendulum of a given mass is pulled back through a given vertical height and released to swing back down to a 'wall' where it impacts. Can i use mg delta h to get E kin; and then use E= half mv^2 to get the collision impact velocity? Would someone check my thinking ...
December 5, 2008

Physics, Collisions
A pendulum of a given mass is pulled back through a given vertical height and released to swing back down to a 'wall' where it impacts. Can i use mg delta h to get E kin; and then use E= half mv^2 to get the collision impact velocity? Would someone check my thinking ...
December 4, 2008

Geography
Wouldn't the ground soak up the water? The sediment would come from the surrounding mountains.
November 19, 2008

Geography
I think sediment would build up on the valley floor and raise the elevation. And a lot more vegetation would grow. Am I close?
November 19, 2008

Geography
If Death Valley was located in an area with a lot of rainfall, how would the valley floor change? How would Death Valley change? Thanks!
November 19, 2008

Geology/Glaciers
Why do north facing slopes on mountains support glaciers today while south facing slopes do not?
November 12, 2008

Physics SHM
Sorry Bob, The wave represents a simple pendulum. In 3, I'm referring to the equation x(t)=Asin(wt+(greek letter phi)), so was looking to confirm that in that specific circumstance I outlined, the value of phi would either be zero or pi (as in 22/7). Thanks.
November 5, 2008

Physics SHM
Am self studying SHM, so sorry for the elementary questions. Would someone check/confirm some facts i think I've learned please. 1 If a sine wave graph starts at the origin at time = 0s, the sysyem is in equilibrium? 2 The amplitude at t= 0s is zero. 3 Same system, the ...
November 5, 2008

Physics SHM
Whether or not it'll help me, am i safe to deduce that: If a simple pendulum is released from rest at time t=0; from a displacement of x rad from equilibrium; Then the amplitude of the oscilation is also x rad? Thanks
November 3, 2008

math
what is the rest of the problem?
October 13, 2008

Physics
If a space station must "provide one sixth the magnitude of the acceleration due to gravity on Earth" Can I use 9.81ms^-2/6 or is that too simple? Thanks.
October 9, 2008

Physics/mechanics
Thank you very much
October 1, 2008

Physics/mechanics
I have to do calculations based upon a bow shooting an arrow vertically, and I have to state any assumptions i'm making. Am I right to cite air resistance as negligible; and that the displacement will start 2m above the ground (not at ground level)? The rest I'm ok with.
October 1, 2008

physics
While her kid brother is on a wooden horse at the edge of a merry-go-round, Sheila rides her bicycle parallel to its edge. The wooden horses have a tangential speed of 6 m/s. Sheila rides at 4 m/s. The radius of the merry-go-round is 8 m. At what time intervals does Sheila ...
September 29, 2008

Math
I posted another question accidentally as an answer to my question
September 12, 2008

Math
I looked at that sight and can see the tables but what I have is a table that show the heights of students in a class males on top females on bottom with heights out beside them. I have to make a cumulative frequency table from the data in my collumns I have, height,frequency ...
September 12, 2008

Math
How do you make a cumulative frequency table
September 12, 2008

college
what's the most commonly overlooked reason for forgetting?
September 9, 2008

GEOGRAPHY
please could someone help, i need to find information about broughton chester airbus to write an essay about it.i need to write about what is made there how the parts are transported to different places how big the factory is what alterations have been made to the factory. ...
May 19, 2008

CHEMISTRY
I'm struggling with this homework question...i have no idea how to set this up. We start with a 33.50 mL aliquot of acetic acid and titrate it with 0.215 M of NaOH. Find the pH at: 21.7 ML added the equivalence point i don't understand how this works. please help, ...
May 18, 2008

Physics
A spring of k=11 N/m has a block of mass 4 kg attached to it on a frictionless table. If the block is pulled a distance 0.15 m to the right and released from rest, how long will it take the block to return to its equilibrium position?
April 28, 2008

Physics
The position of some object moving along the x-axis is observed to be x(t)=9cos(pi*t/3+pi/4) meters. Find the frequency.
April 28, 2008

French Pen-Pal
Me and my french pen pal enjoy chatting about our opinions of things. Maybe one of her favourite films (?) are on of the worst in your opinion. So tell her your own opinion. We also like talking about what's in our town (where we live) and what we love to do on the weekend...
April 20, 2008

Algebra
How do you convert money to pecent?
April 8, 2008

chem
Dude, That is a freakin HAAAAARRRDDD guestion. your in colledge right??
April 7, 2008

Science
MRIs use very powerful electo magnets>
April 7, 2008

Physics
I'm still not getting the right answer. It asks to convert it to centimeters but even when I do that I am still getting it wrong.
April 6, 2008

Physics
An advertisement claims that a centrifuge can produce a radial acceleration of 3,524g at 4,608 rev/min. Calculate the required radius of the centrifuge.
April 6, 2008

Physics
An object of mass 3.5x1023kg circles the earth and is attracted to it with a force whose magnitude is given be GMeM/r^2. If the period of rotation is 22 days, what is the distance from the earth to the object? Here G=6.67x10-11 Nm2/kg2, Me=6x1024 kg.
April 5, 2008

Physics
Suppose you are driving a car around in a circle of radius 157 ft, at a velocity which has the constant magnitude of 42 ft/s. A string hangs from the ceiling of the car with a mass of 1.8 kg suspended from it. What angle (in degrees) will the string make with the vertical?
April 5, 2008

Physics
A cannon shoots a shell straight up. It reaches its maximum height, 837 feet, and splits into two pieces, one weighing 2 lb and the other 5 lb. The two pieces are observed to strike the ground simultaneously. The 5 lb piece hits the ground 1,564 feet away from the explosion (...
March 29, 2008

Physics
OK thanks. There is another part of the question that asks for the momentum of the 4 lb piece and I can't figure out how to solve that.
March 29, 2008

Physics
A cannon shoots a shell straight up. It reaches its maximum height, 1,051 feet, and splits into two pieces, one weighing 2 lb and the other 4 lb. The two pieces are observed to strike the ground simultaneously. The 4 lb piece hist the ground 1,608 feet away from the explosion...
March 29, 2008

Physics
sorry I don't know what happened but I posted it again and the question is on there.
March 29, 2008

Physics
A cannon shoots a shell straight up. It reaches its maximum height, 1,051 feet, and splits into two pieces, one weighing 2 lb and the other 4 lb. The two pieces are observed to strike the ground simultaneously. The 4 lb piece hist the ground 1,608 feet away from the explosion...
March 29, 2008

Physics
You are stranded in the middle of a frozen pond, 825 m in diameter which is so slippery that your feet slide freely and don't move you. In desperation you write an S.O.S. on your hat, mass 0.6 kg, and fling it towards the north with a velocity of 13 m/s at 54o with the ...
March 28, 2008

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