Tuesday
May 5, 2015

Posts by andrew


Total # Posts: 1,040

chemistry
its C your original answer
November 10, 2012

chemistry
indeed
November 10, 2012

chemistry
Think a little more.. you have 1.25e23 atoms, and there are 6.02e23 atom in one mole. dividing the first by the second yields 2.08e-1 mol Mg
November 10, 2012

Physics
ive previously tried this and obtained 3.34e-13 m/s which the computer says is wrong where N = 8.46e28 m^-3 e = 1.6e-19 C and A = 7.07e-8 m^2
November 10, 2012

Physics
A small but measurable current of 3.20 E-10 A. exists in a copper wire whose diameter is 0.03 cm. Calculate the electron drift speed (in meters/second).
November 10, 2012

chemistry
you think correctly
November 10, 2012

math
denominator is the number beneath the line of a fraction. e.g. x/4 we know that 1/4 wont work, neither will 2/4 (1/2) nor 4/4 (1). That leaves us with one option 3/4 3/4 is greater than 1/2 but less than 1 and has a 4 in the denominator Hope that helps!
November 10, 2012

chemistry
you have the correct answer and are looking for an explanation? there are three nitrates of formula NO3. since there are 3 oxygen atoms per nitrate, and 3 nitrates total. 3x3 = 9 oxygen atoms per nitroglycerin
November 10, 2012

biology
d = m/v v = 5.18^3 m = 197g d = 197/(5.18^3) answer is in g/cm^3
November 10, 2012

nuclear chemistry
E=mc^2 10^6 J/s are being produced (1Mw) 10^6 J/s = m (3.0e8 m/s) solve for mass to find amount of mass lost in one second. ~ .0033kg
November 10, 2012

Physics deflection ammeter
thank you bob!
November 10, 2012

Physics deflection ammeter
8. A galvanometer has a coil resistance of 100 ohms and gives a full scale deflection when the potential difference across it is 0.0002 V. What size resistor (with a value measured in ohms) is required to make a 1.0 A. full scale deflection ammeter?
November 10, 2012

Capacitor
A parallel plate capacitor with plates of area 320 cm.^2 is charged to a potential difference V and is then disconnected from the voltage source. When the plates are moved 0.3 cm. farther apart, the voltage between the plates is increased by 152 V. What is the charge on the ...
November 4, 2012

Capacitance
A parallel plate capacitor with plates of area 320 cm.^2 is charged to a potential difference V and is then disconnected from the voltage source. When the plates are moved 0.3 cm. farther apart, the voltage between the plates is increased by 152 V. What is the charge on the ...
November 3, 2012

Chemistry
Tiffany, Assuming the reaction runs to completion and there is an excess of Al you know that Bromine is your limiting reagent. Stoichiometry will give you the amount of AlBr2 produced. You begin with 7.9 mol Br2 to cancel the moles of Bromine and find moles of Aluminum Bromide...
November 3, 2012

Capacitance (tricky)
Thanks! Our textbook did not cover dielectrics very well.
November 3, 2012

Capacitance (tricky)
Two parallel plates of area 41 cm.^2 have equal but opposite charges of 2.60E-07 C. Within the dielectric material filling the space between the plates, the electric field is 5.80E+05 V./m. Find the dielectric constant of the material. Feel like there is a huge lack of ...
November 3, 2012

physics
Alyssa, I suggest you draw a freebody diagram of the wagon and the handle. Youll notice that the handle has a force of magnitude 20N with a direction of 25 degrees above the horizontal. Now write your force summation using Newton's second law. Let Ft be the magnitude of ...
November 3, 2012

John Jay
what is sum or defference of 3/8 + 3/5
October 26, 2012

calculus
(a) Find the number c such that the limit below exists. Limit as x goes to -2 of: x^2+cx=c-3/x^2+2x (b) Calculate the limit for the value of c in part (a).
October 24, 2012

math
2 half dollars, 4 quarters, 2 dimes and 1 penny .50+.50+.25+.25+.25+.25+.10+.10+.01=2.21 2+4+2+1=9
October 24, 2012

Math
(a) Find the number c such that the limit below exists. Limit as x goes to -2 of: x^2+cx=c-3/x^2+2x (b) Calculate the limit for the value of c in part (a).
October 24, 2012

Physics Conducting Spheres
1. Two concentric conducting spherical shells have radii of 0.145 m. and 0.215 m. The inner sphere bears a charge of -3.00E-08 C. An electron escapes from the inner sphere with negligible speed. Assuming that the region between the spheres is a vacuum, compute the speed (in ...
October 21, 2012

physics
c)what is the balls speed just after the bounce?
October 11, 2012

physics
You drop a ball from a height of 1.9m , and it bounces back to a height of 1.3m . a)What fraction of its initial energy is lost during the bounce? b)What is the ball's speed just before the bounce?
October 11, 2012

Physics
Standing on a balcony, you throw your keys to a friend standing on the ground below. 1.2 seconds after you release the keys, they have an instantaneous velocity of 15.7 m/s, directed 52° below the horizontal. What initial velocity did you give them?
September 20, 2012

Physics
Standing on a balcony, you throw your keys to a friend standing on the ground below. 1.2 seconds after you release the keys, they have an instantaneous velocity of 15.7 m/s, directed 52° below the horizontal. What initial velocity did you give them?
September 20, 2012

Physics
What is the speed of the rocket when it is 350 above the surface of the earth? A rocket starts from rest and moves upward from the surface of the earth. For the first 10 of its motion, the vertical acceleration of the rocket is given by a(y)=2.9, where the -direction y+ is ...
September 9, 2012

Physics
A 160lb person steps into an elevator and stands on a bathroom scale. what is the weight on the scale when the elevator accelerates upwards at 2ft/s^2
August 26, 2012

chemistry
The average human body has 1.4x10^2 g of total K within it. Calculate the activity in disintegration/year of the potassium-40 in the average human body using your value of t1/2 (or K) of this substance
August 22, 2012

calculus
f(x)=[lnx]^5
July 19, 2012

physics, please help me, this question is hard
John Stands at the edge of a flat roof of a three story building and throws a 180g ball straight up into the air that reaches a height of 3.0 meters above the roof. ( building is 14 meters high) A. What is the initial speed of the ball? B. How long does it take to reach it'...
July 5, 2012

help please :)
yeah write teacher you are extremely rude get some manners
June 19, 2012

Chemistry
For 105ml of a buffer that is .40 M in HOCL and .36M in NaOCL what is the pH after 13.4 ml of 1.5M NaOH is added? Ka for HOCL is 3.5x10^-8
June 12, 2012

Chemistry
Alright, I got it thanks!
June 4, 2012

Chemistry
I'm messing up somewhere 1x10^30= [.011-x]/[x][.836+4x]^4 4.8x10^29(x)+2.56x10^32(x^5)=.011-x Factoring out an x and moving all terms x(4.8x10^29+2.56x10^32(x^4))-.011+x=0 Then because of the relative size I assumed -.011 and x are negligible x(4.8x10^29+2.56x10^32(x^4))=0...
June 4, 2012

Chemistry
What is the concentration of Hg^2+ in 500.0 mL of a solution that was originally 0.011 M Hg^2+ and had 73 g of KI added to it? Hg^2+(aq) + 4I^-(aq)<=> HgI4^2-(aq) The overall formation constant is 1x10^30
June 4, 2012

physics
A building has become accidentally contaminated with radioactivity. The longest-lived material in the building is strontium-90. (The atomic mass of Sr is 89.9077 u.) If the building initially contained 4.8 kg of this substance and the safe level is less than 10.0 counts/min, ...
June 3, 2012

physics
After 1.84 days, the activity of a sample of an unknown type radioactive material has decreased to 85.8% of the initial activity. What is the half-life of this material? (in days)
June 3, 2012

Chemistry
Alright, I was able to figure them all out. Thank you!
June 1, 2012

Chemistry
So for the first portion I came to Kb=1.5x10^-10 then x^2/.14-x= 1.56x10^-10 x^2-(2.2x10^-11)x - 1.56x10^-10=0 solving with the quadratic equation I came to x= 1.25x10^-5 (I'm disregarding i) So -log(1.25x10^-5)= 4.9 But somewhere I've done something wrong as the ...
June 1, 2012

Chemistry
Calculate the pH at the halfway point and at the equivalence point for each of the following titrations. (a) 100.0 mL of 0.14 M HC7H5O2 (Ka= 6.4 multiplied by 10-5) titrated by 0.14 M NaOH halfway point equivalence point (b) 100.0 mL of 0.29 M C2H5NH2 (Kb = 5.6 multiplied by ...
June 1, 2012

science
Its C...Nodules of certain plants such as clover fix Nitrogen to the soil...thats the reason farmers grow cver ...then plow it back into the soil..Natural source of Nitrogen...dontknow about the others...
May 31, 2012

Introduction to Psychology
way too much time on phone...in the shower..and on Facebook..:)
May 31, 2012

Math
Add it up...here goes..6 X $9.80...plus 1/4 hour =15 mins...so work out 1/4 of $9.80...remember 1/4 = 25%....then 7 x $14.50...plus 30 mins at $14.50/hr...remember 30 mins is 1/2 an hour so whats $14.50 divided by two..?...now add it all up and theres you answer...!
May 31, 2012

Art
Spanish Romanticism...not sure about any other....its oil on canvas (1820)
May 30, 2012

math
11,,,,,,!!!!
May 29, 2012

math
3y-12=21
May 29, 2012

math
It says Complete 10/3 on maths homework...what does this mean...thanks.. :)
May 29, 2012

chemistry
Its c....K= potassium...and there is is only one mentioned...and Cl= chlorine...again only one mentioned.. So its C...look up your elements table and it will tell you what K..is etc...then you wont have to send as many questions in...!!
May 28, 2012

chemistry
Its D..!!...the 2 after the Br means its attached to that element..so read as 2 X Br....there is nothing after the Mg...so that means there ais only one So therefore its D...
May 28, 2012

Minoxidil
C9H15N2O...chemical formula
May 28, 2012

Minoxidil
Try under its more common name "Rogaine"...its basically a chemical that slows hair loss....
May 28, 2012

Religion
Its Islam = Peace
May 28, 2012

Physics
A convex lens forms a real image 6 times the size of the object. The distance between object and image is 33 cm. Find the focal length of the lens.
May 28, 2012

physics
An object is placed 75.0 cm from a screen. (a)Where should a converging lens of focal length 8.0 cm be placed to form an image on the screen? shorter distance __cm from the screen farther distance __cm from the screen (b)Find the magnification of the lens. magnification if ...
May 23, 2012

Chemistry
Find [H+] [OH-] and Ph
May 21, 2012

Chemistry
A solution is prepared by adding 47.3 mL of concentrated hydrochloric acid and 16.3 mL of concentrated nitric acid to 300 mL of water. More water is added until the final volume is 1.00 L. Calculate [H+], [OH -], and the pH for this solution. [Hint: Concentrated HCl is 38% HCl...
May 21, 2012

physics
Calculate the magnitude and direction of the Coulomb force on each of the three charges connected in series: 1st - 6 micro Coulombs (positive charge) 2nd - 1.5 micro Coulombs (positive charge) 3dr - 2 micro Coulombs (negative charge) Distance between 1st and 2nd - 3cm Distance...
May 21, 2012

physics
An object is placed 75.0 cm from a screen. a)Where should a converging lens of focal length 8.0 cm be placed to form an image on the screen? shorter distance __cm from the screen farther distance __cm from the screen b)Find the magnification of the lens. magnification if ...
May 21, 2012

physics
A wire of initial length L0 and radius r0 has a measured resistance of 2.5 . The wire is drawn under tensile stress to a new uniform radius of r = 0.45r0. What is the new resistance of the wire?
May 21, 2012

physics
An air-filled capacitor consists of two parallel plates, each with an area of 7.60 cm2, separated by a distance of 1.70 mm. If a 19.2-V potential difference is applied to these plates, calculate the following: (a) the electric field between the plates, magnitude (in kV/m) and ...
May 18, 2012

physics
The potential difference between the accelerating plates of a TV set is about 30 kV. If the distance between the plates is 1.1 cm, find the magnitude of the uniform electric field in the region between the plates. (in N/C)
May 17, 2012

physics
Calculate the magnitude and direction of the Coulomb force on each of the three charges connected in series: 1st - 6 micro Coulombs (positive charge) 2nd - 1.5 micro Coulombs (positive charge) 3dr - 2 micro Coulombs (negative charge) Distance between 1st and 2nd - 3cm Distance...
May 16, 2012

Chemistry
Consider the following reaction: 2NOCl(g) 2NO(g) + Cl2(g) Initially pure NOCl(g) is placed in a vessel at 3.00 atm. At equilibrium, 0.416% of the NOCl has decomposed. Determine the value for Kp.
May 13, 2012

Chemistry
For the reaction below, Kp = 1.16 at 800.°C. CaCO3(s) CaO(s) + CO2(g) If a 25.0-g sample of CaCO3 is put into a 10.2-L container and heated to 800.°C, what percent of the CaCO3 will react to reach equilibrium?
May 12, 2012

Science
Table salt has a solubility of 36 g of salt in 100 g of water at 40°C. If 15 g of the salt are added to 50 g of water at the same temperature, is the resulting solution saturated or unsaturated? Explain your answer
May 11, 2012

Math
The question asks the opposite... not yellow. so 9/12 * 10/15 = .75 * .666 = 50%
May 9, 2012

Physics
calculate change in the momentum. remember that after it experiences this "perfectly elastic collision" it has a negative velocity. Therefore the change in momentum would be p = abs|m1v1 + m2v2| change in momentum p = Ft Force would be the average force or in this ...
May 9, 2012

Chemistry
solve q initial for the 240g of coke/water. solve q initial for the ice. subract q ice from q coke, then solve for deltaT q(coke) - q(ice) = (4.18 J/gK)(285g)(deltaT)
May 9, 2012

?
brought
May 8, 2012

chemistry
4Na + 02 = 2Na2O Considering Na is the limiting reagent.. 1.15g Na x 1molNa/23g x 2molNa2O/4molNa x 1molNa2O/62g = grams of Na2O
May 8, 2012

Environmental Chemistry
This is a strong acid/base titration. Balance your equation for the reaction and calculate if you have excess H30+ or OH- Remember that pH=-log[H30+] and pOH = -log[OH-] pOH = 14 - pH Where [H30+] and [OH-] is the concentration of each substance in moles/liter
May 8, 2012

physics
0 J
May 7, 2012

math
A dodecagon is the term for a regular 12 sided polygon with equivalent angles and side lengths. Looks like most the other regular 2D polygons. If its irregular.. use your imagination
May 7, 2012

physcis
1. Fnet=ma=Fs Fnet=ma=usFn Fnet=ma=usmg mass cancels a=usg Please stop reposting your question
May 7, 2012

physics
No energy will be required, as no work is being done one the weight as it is carried across the room. Wnc = Fdcos90 cos90 = 0 Wnc = 0 Wnc = change in Emech change in Emech = 0
May 7, 2012

physics
1. Fnet=ma=Fs Fnet=ma=usFn Fnet=ma=usmg mass canceles a=usg 2. not a very good visual description, cant figure out what you mean. draw pictures. use a free body diagram
May 7, 2012

Chemistry
DxDp = h/4p Where Dx is uncertainty of position, Dp is uncertainty in momentum, h is Planck's constant 5.26e-33 Joule seconds, and p is linear momentum, P = mv.
May 7, 2012

physics
A potential difference of 102 mV exists between the inner and outer surfaces of a cell membrane. The inner surface is negative relative to the outer surface. How much work is required to eject a positive sodium ion (Na+) from the interior of the cell? (in J)
May 7, 2012

physics
An electron is accelerated by a constant electric field of magnitude 325 N/C. (a) Find the acceleration of the electron. (m/s^2) (b) Use the equations of motion with constant acceleration to find the electron's speed after 1.05 10-8 s, assuming it starts from rest. (m/s)
May 6, 2012

Accouting
How much investment per dollar of expected annual operating savings can a company afford if the investment has an expected life of 8 years and its required rate of return is 14%?
May 5, 2012

physics
A 8.01-nC charge is located 1.95 m from a 4.06-nC point charge. (a) Find the magnitude of the electrostatic force that one charge exerts on the other. (b) Is the force attractive or repulsive?
May 5, 2012

physics
Two loudspeakers are placed above and below each other and driven by the same source at a frequency of 3.70 102 Hz.An observer is in front of the speakers at point O, at the same distance from each speaker. What minimum vertical distance upward should the top speaker be moved ...
May 3, 2012

physics
Tension is maintained in a string. The observed wave speed is 21 m/s when the suspended mass is 3.0 kg. a) What is the mass per unit length of the string? (in kg/m) b) What is the wave speed when the suspended mass is 1.6 kg? (in m/s)
May 2, 2012

Marketing
I need help coming up with 3 realistic Objectives for NIKE SHOES that would be used on a marketing plan. The objectives needs to be Specific, Measurable, Attainable, Realistic and Time Sensitive.
April 30, 2012

Calculus
Use the form of the definition of the integral to evaluate the intergral. From 0 to 9 (10+6x-x^2)
April 20, 2012

physics
3.3m/s2
April 20, 2012

Physics (Energy and Momentum)
solved
April 17, 2012

Physics (Energy and Momentum)
A block of mass m1 = 1.00 kg slides along a frictionless table with a speed of 16.0 m/s. Directly in front of it, and moving in the same direction, is a block of mass m2 = 6.00 kg moving at 8.00 m/s. A massless spring with a spring constant k = 1320 N/m is attached to the ...
April 17, 2012

Physics (Energy and Momentum)
solved using thrust = v (dM/dt)
April 17, 2012

Physics (Energy and Momentum)
A 4400 kg rocket is set for vertical firing. If the exhaust speed is 1500 m/s, at what rate (in kilograms/second) must the gas be ejected to supply the thrust needed to give the rocket an initial upward acceleration of 23.0 m/s^2? Not sure where to start.
April 17, 2012

Physics (Energy and Momentum)
A body of 5.10 kg mass makes an elastic collision with another body at rest and continues to move in the original direction, but with one-fourth of its original speed. What is the mass (in kilograms) of the struck body? Assuming a perfectly elastic collision, KEi=KEf ive tried...
April 16, 2012

Physics Mechanics (unsolved)
An electron of mass 9.1E-31 kg is released from rest at a distance of 7.1 E-10 m from a fixed electron. The force on the movable electron is given by the function F = 2.3E-28/r^2, where r is the distance between the electrons. Find the maximum velocity (in meters/second) of ...
April 13, 2012

Physics (Mechanics) - unanswered
An electron of mass 9.1E-31 kg is released from rest at a distance of 7.1 E-10 m from a fixed electron. The force on the movable electron is given by the function F = 2.3E-28/r^2, where r is the distance between the electrons. Find the maximum velocity (in meters/second) of ...
April 13, 2012

Physics (Mechanics)
An electron of mass 9.1E-31 kg is released from rest at a distance of 7.1 E-10 m from a fixed electron. The force on the movable electron is given by the function F = 2.3E-28/r^2, where r is the distance between the electrons. Find the maximum velocity (in meters/second) of ...
April 12, 2012

physics (mechanics)
A running man has half the kinetic energy of a boy half his mass. The man speeds up by 1.30 m/s and then has the same kinetic energy as the boy. What is the speed (in meters/second) of the boy?
April 12, 2012

Math 1200
a complex has 205 apartment units. When the rent is $635 per month all 205 units are occupied.Assume that for each $75 increase in rent 15 units becomes vacent. Assume that the number of occupied units is a linear function of the rent. Each occupied unit also requires an ...
April 5, 2012

Math
Jim has 400 ft of fence material and needs to enclose an area of 10,000 square feet for his garden as the diagram depicts. (The length of the house is 62 ft and the fence extends the same distance on either side of the house.) What must the dimensions of the rectangular ...
March 27, 2012

Physics
In the dangerous "sport" of bungee-jumping, a daring student jumps from a balloon with a specially designed elastic cord attached to his waist, as shown in Figure P5.77. The unstretched length of the cord is 25.0 m, the student weighs 675 N, and the balloon is 36.0 m...
March 25, 2012

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