# Posts by Charlie

Total # Posts: 487

college physics
A box on a frictionless horizontal surface is pulled by a tension of 42.4N directed at 45 degrees above the horizontal. what is the work done on the box as it moves 2.50 meters along the surface?

college physics
A box on a frictionless surface is pulled back a distance x into a spring with spring constant k and released. What is the formula for the kinetic energy of the box after it leaves the spring?

College Physics
A 50 kg skater moving at 5 m/s over frictionless ice grabs a rope stretched out 10m from a post and perpendicular to her path. She then moves in circles, spiraling inward as the rope wraps around the post. How fast is she moving when she is 2 meters from the post?

3p - 1.5

math
let me retype the question. Sorry for the scribble. 1/2 X 1/2 answer in simplest form. must show work. thanks

math
desperately seeking help. work must be shown. answer must be in simplest form. Thanks 1 1 _ X _ 2 2

mat115
There are multiple choices for the answer to this problem. They are a) 1/5 b) undefined c) 5 d) 5/7 Thanks again for both of your help

mat115
Sorry Reiny, The question is 11-6/7-7 I thought the answer was 5/0= undefined. Can you please let me know if I am wrong and show the work so I can further understand your answer. Thanks Reiny

Math
Thanks Reiny, Yes, I spotted that it dosen't work for any run of primes, but it does up to 9. I'm afraid i don't really follow your explanation! An answer for dummies maybe? Charlie

Math
I have to find the relationship between these sequences, and express a generality. Could you help please. 1 + 3 + 5 + 3 + 1 = 3^2 + 2^2 1 + 3 + 5 + 7 + 9 + 7 + 5+ 3 + 1 = 5^2 + 4^2 1 + 3 + 1 = 2^2 + 1^2 I'm thinking sum of consecutive primes can be expressed in squares? ...

Physics
It's too hard. You should give up now

gen.science
A compound containing 3 atoms of carbon and 8 atoms of hydrogen is combined in a reaction with oxygen molecules. The two end products of this equation are carbon dioxide and water. Which chemical or element will have the largest number of moecules?

chemistry
What was the purpose of the phenolphthalein?

Math algebra
I'm reposting this, because Mathmate's answer hasn't directed me to the WHY? part of the question. Any prompts appreciated. The product of any two (whole) numbers each of which leave a remainder of 1 on dividing by 7, also leaves a remainder of 1 on dividing by 7...

math
I have this question to work on, and I don't know where to start investigating the answer: The product of any two (whole) numbers each of which leave a remainder of 1 on dividing by 7, also leaves a remainder of 1 on dividing by 7. Why? I THINK that I can see a quadratic ...

physics
If the angular quantities θ,ω,α were specified in terms of degrees rather than radians, how would the kinematics equations for uniformly accelerated rotational motion have to be altered?

Physics
Ok thanks, but why isn't this true for an arm or leg?

Physics
Why is the CM of a 1.00m length of pipe at its midpoint, whereas this is not true for your arm or leg?

Math
I need to figure out what a deposit of 3500 a month, with 9 percent intrest compounded monthly, would be in 6 years. Any help would be greatly appreciated.

Math
I need to figure out what a deposit of 3500 a month, with 9 percent intrest compounded monthly, would be in 6 years. Any help would be greatly appreciated.

math
-3/4

freedom
iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiissssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssss WAR.

Biology
What differences would you expect to see in a population made up of individuals whose chromosomes experience crossing-over frequently compared with a population made up of individuals whose chromosomes do not cross over?

algebra
x+12+x-5+x=40 3x+7=40 3x=33 x=11 x-5+6 x+12=23 23, 11, 6

AP Physics B
can u give me these in numbers please, i don't understand what formulas u wrote and what some of the stuff in ur formulas are

AP Physics B
i figured out the amplitude and the period, i just don't kno how to get to the other 4 with using simple harmonic motion equations

AP Physics B
The position of a 20 g oscillating mass is given by x(t) = (2.0 cm) cos(2t), where t is in seconds. Determine the following. The Amplitude (cm.) The Period (s.) The Spring Constant (N/m) The maximum speed (cm/s) The total energy (J) The velocity at t=0.40 s. (cm/s) I need your...

Chemistry
The titration of 25.0 mL of an unknown concentration H2SO4 solution requires 83.6 mL of 0.12 M LiOH solution. What is the concentration of the H2SO4 solution (in M)? A) 0.40 M B) 0.10 M C) 0.20 M D) 0.25 M E) 0.36 M The answer is supposedly C, but I got A. What am I doing ...

Chemistry
Uranium-235 can be separated from U-238 by fluorinating the uranium to form UF6 (which is a gas) and then taking advantage of the different rates of effusion and diffusion for compounds containing the two isotopes. Calculate the ratio of effusion rates for 238UF6 and 235UF6 ...

Chemistry
Thanks so much! I got 4.82 which seems to be correct. Thank you again

Chemistry
Consider the following reaction: 2NiO (s)--> 2Ni(s) + 2O2 (g) If O2 is collected over water at 40.0 C and a total pressure of 752 mmHg, what volume of gas will be collected for the complete reaction of 25.67 g of NiO? I am struggling to set up this problem. Can anyone help ...

Physical Science
What is cracking and reforming? For what purposes are either or both used by the petroleum industry

Physics
I'm not doing the measuring, it's a graphing exercise, and I've been given the table of data. I was looking for confirmation of my choice of axes. But your extra points are well taken. Thanks for your comment.

Physics
I have to plot a graph of Pressure gradient vs average velocity (water in a pipe, I have all the data). I plan to put the average velocity on the x axis, since I could control that better in an experiment. Do you agree/ Thanks. Charlie

english
this is the quesion List four things to look for when you’re proofreading?

english
If you’re asked to list for things can the way of your listing be vertical or horizon.

Physics
Would someone check this please? A circular loop of wire of radius 0.10 m and of resistance 2.0 x 10^−3 ohms is in a region where there is a uniform magnetic field B. The field is at 30deg to the normal to the plane of the wire loop as shown in Figure 3. The magnitude of...

physics
The last stage in the fusion of hydrogen to form helium in the Sun involves the formation of an alpha particle (4He) from two 3He nuclei: 3He + 3He 4He + p + p The binding energy for 3He is 2.57 MeV per nucleon and that for 4He is 7.07 MeV per nucleon. Calculate the amount of ...

Physics
Would someone check this please? A circular loop of wire of radius 0.10 m and of resistance 2.0 x 10^−3 ohms is in a region where there is a uniform magnetic field B. The field is at 30deg to the normal to the plane of the wire loop as shown in Figure 3. The magnitude of...

Physics
The last stage in the fusion of hydrogen to form helium in the Sun involves the formation of an ƒ¿-particle (4He) from two 3He nuclei: 3He + 3He ¨ 4He + p + p The binding energy for 3He is 2.57 MeV per nucleon and that for 4He is 7.07 MeV per nucleon. ...

Physics
Would someone check this please? A circular loop of wire of radius 0.10 m and of resistance 2.0 ~ 10−3 ƒ¶ is in a region where there is a uniform magnetic field B. The field is at 30‹ to the normal to the plane of the wire loop as shown in ...

Physics
In an elastic collision: mass a is 1kg, and is moving at 100ms^1 in the +ve x direction when it hits mass b, 10kgs at rest. Given: mass a moves off at 80 ms^1 in the -ve x direction. What's the final velocity of mass b. Using cons of momentum, i say 2 ms^1 in the +ve x ...

physics
Thanks for that. So it would take longer to stop then?

physics
Would someone check my thinking please. A solid sphere (mass, r, and moment of inertia given) is rotating at a given angular speed. Friction is constantly applied at the 'equator' of the sphere, and brings it to rest in 3s. Find the force. I worked out the torque, and ...

Physics/Maths
Thanks

Physics/Maths
Keplers third law I understand. T^2/a^3 of one planet = T^2/a^3 second planet. But I can't do the algebra to solve for the second planet's a^3 (semimajor axis) Would someone walk me through the steps please? Thanks.

Entropy
Thanks for that.

Entropy
If a sample of an ideal gas is heated at a constant volume, I believe its entropy will increase. Am I right? Thanks.

Physics capacitance
Thank you very much.

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.

Thermodynamics
Thank you for giving such a detailed answer.

Thermodynamics
Would someone explain entropy in simple terms please. Thanks.

HELP! Time running out! Thanks

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 ...

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

physics
Thanks, CI

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?

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

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

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

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

math
write the next four letters in this sequence A B Z Y C D

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 ...

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 ...

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

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

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

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...

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

math
the response from Ms writeacher did not show the answer

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?

math
Thanks Jessica

math
what is the value of 4 in 0.045

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?

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?

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?

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

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...

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...

biology
can i get some help here please? much appreciated.

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

Very kind drwls, thanks a lot. Charlie

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 ...

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

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?

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...

Physics
that's 3x10^6, not -6

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

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 ...

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

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...

physics, fluids
Thanks, all 3.

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.

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

Human Anatomy
What are the bony landmarks of the abdominopelvic cavity?

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 (:

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

physics
Spotted! Thanks Dr Bob.

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

Physics ideal gases
Thank you both.

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