Saturday

October 10, 2015
Total # Posts: 845

**physics (Compton effect)**

need helppp. Find the energy of an x-ray photon that can impart a maximum energy of 50 keV to an electron by Compton collision. Max energy being Kinetic Energy? do I just plug the 50*10^3 eV (convert to J) into the E=h (c/lambda) equation?? We are not given theta, the incident...
*October 10, 2015*

**Chemistry**

Rules for addition and sig figs are that you go by the decimal place. 2.1 has 1 decimal place. So the answer has to have 1 decimal place as well. 1.3*10^4.
*October 7, 2015*

**chemistry (inorganic) reflection planes**

how many planes of reflection (sigma v) does the letter "H" have? an infinite amount? this is for an intro to group theory / symmetry operations.
*October 7, 2015*

**Math**

wait just kidding, its already noted that Y is the product, so it would be C, my bad.
*October 7, 2015*

**Math**

I would go with B. It's the only choice that states the product is greater than 4.
*October 7, 2015*

**chemistry uncertainty rule**

if I want to find the uncertainty for a certain molar mass containing 4 atoms of Oxygen, do I multiply the error and the MM by 4: like this 4(15.9994 plus of minus .0003) = 63.9976 plus or minus .0012 (distribute the 4?) or follow the rules for mult. of uncertainty which would...
*September 25, 2015*

**Math**

Identify the build up of the Sine-Bar to represent the angle. Identify the angle in degrees, minutes and seconds of the arc. Sine29(angle), 17'(minutes),57"(seconds)
*September 19, 2015*

**math**

make one equation = 0 so 2(0)-3y=6 3y/3=6/3 y=2 now 2x-3(2)=6 2x-6=6 2x=6+6 2x=12 2x/2=12/2 x=6 now sub that it to the other side y=4(6)-7 y=24-7 y=17 2=4x-7 2+7=4x 9=4x 9/4=4x/4 2.25=x
*September 19, 2015*

**chemistry**

would NBr3O be polar or nonpolar?
*September 18, 2015*

**Chemistry**

use the formula q = m*c*deltaT
*September 17, 2015*

**chemistry polarity **

would one consider the molecule NBr3O to be nonpolar or polar? I feel like all of the dipole moments will cancel, when you draw the VSPER structure the Br atom in the plane and out of the plane cancel, however O going up and the Br coming out of the plane, ...I feel like the ...
*September 17, 2015*

**chemistry vsper/lewis polarity**

would one consider the molecule NBr3O to be nonpolar or polar? I feel like all of the dipole moments will cancel, when you draw the VSPER structure the Br atom in the plane and out of the plane cancel, however O going up and the Br coming out of the plane, ...I feel like the ...
*September 17, 2015*

**Chemistry**

Mg--->MgO .248 g Mg x (1 mol Mg/MM Mg) x (1 mol MgO/1 mol Mg) x (MM MgO/1 mol MgO) MM are molar masses.
*September 14, 2015*

**physics relativistic energy**

thank you! How would I know not to use the mass of 20 kilotons though? I wish they didn't put that in the question it really throws you off haha
*September 12, 2015*

**physics relativistic energy**

unlessss.... I just solve for mass and the 20 kiloton is just extra useless information meant to throw people off and do this: e=mc^2 m = E/c^2 m = 8*10^13 J / (3.0*10^8 m/s)^2 m= 8.89 * 10 ^-4 kg hmm
*September 12, 2015*

**physics relativistic energy**

I'm not too good with these special relativity problems :/ The question is: A 20 kiloton bomb releases 8 x 10^13 joules. How much mass must be converted into other forms of energy? You are already given Energy, would I still use the E=mc^2 formula?? E=(2.0*10^7 kg)(3*10^8 ...
*September 12, 2015*

**Math**

how much yellow paint is needed to mix with one cup of red paint
*September 10, 2015*

**health part 2**

According to the world wide web, there are 3. 1)Non-nucleoside reverse transcriptase inhibitors 2)reverse transcriptase inhibitors and 3)protease inhibitors. I would say the simple answer is generally "Inhibitors"
*September 2, 2015*

**Physics Lorentz contraction**

This seems like a pretty straightforward question but it's just not making sense at the moment. A meter stick is projected into space at so great a speed that its length appears to have contracted only 50 cm. How fast is it going? So you want the velocity, v. (in terms of ...
*September 2, 2015*

**Chemistry**

A, C, E.
*September 2, 2015*

**math**

you have 2 positive numbers. One number is one-fifth of the other number.The difference between the two numbers is 152, find the numbers.
*September 2, 2015*

**cnn student news world georgraphy**

and why are you unable to listen to the videos on the website?
*August 27, 2015*

**chemistry**

Thanks sir! :)
*August 27, 2015*

**chemistry **

back again with another analytical Q, the question tells you to prep a 50 mL solution of a 750 ppm iron solution using ammonium iron III oxalate trihydrate (MM: 428.06 as a source of iron. Determine the mass of compound required. I'm assuming you would start with a ...
*August 27, 2015*

**chemistry**

first you need to write out the balanced reaction equation of LiOH reacting with CO2. So... 2LiOH + CO2--->Li2CO3 + H2O You start with 920 g CO2 and use this equation to convert to moles CO2 and then to moles LiOH. There are 2 moles LiOH for every 1 mole of CO2. And finally...
*August 27, 2015*

**algebra**

Slope of parallel lines are the same. m = -9/2 here so the new line will have a slope of m= -9/2 as well. Through the points (-2,5) y-y1=m(x-x1) y-5=(-9/2)(x--2) y-5=(-9/2)(x+2) y-5=(-9/2)x+(-9) y=(-9/2)x-4.
*August 19, 2015*

**algebra**

Get the slope: y2-y1/x2-x1 m= (5-4)/(3-4) m= -1 formula y-y1=m(x-x1) pick a set of points. y-4=m(x-4) y-4=(-1)(x-4) y-4=-x+4 y=-x+8 There is the equation.
*August 19, 2015*

**Dimensional Analysis Chemistry**

ahh yes I multiplied by 10^-3 instead lol thank you!
*August 19, 2015*

**Dimensional Analysis Chemistry**

want someone to check if this is right, Q: The concentration of lead in drinking water in a home was found to be 2.1x10-9 M. What is the concentration in ppm? ppb? MM=207.2 g/mol. 1 ppm = 1 mg/L. A: 2.1x10^-9 mol/L x 207.2 g/ 1 mol x 1000 mg / 1 g = 4.35x10^-4 ppm. and that is...
*August 19, 2015*

**physics**

A bicycle is rolling down a circular portion of a path; this portion of the path has a radius of 8.73 m. As the drawing illustrates, the angular displacement of the bicycle is θ = 0.979 rad. What is the angle (in radians) through which each bicycle wheel (radius = 0.320 m...
*August 5, 2015*

**accounting**

47059
*July 19, 2015*

**PSYCH**

Unlike the Rescorla Wagner model, Mackintosh's theory of attention states that: A. subjects can learn to pay increased attention to informative CSs. B. subjects can learn to pay less attention to uninformative CSs. C. Both a and b D. Neither a nor b PLEASE HELP
*July 16, 2015*

**math**

on monday 464 students went on a trip to zoo .all 9 buses were filled and 5 students had to travel in cars. how many students were in each bus?
*May 25, 2015*

**Mathematics**

A motorist drives 80km/h at an average speed of 63km/h. Which average is this: mean, mode, median?
*May 23, 2015*

**physics **

If an object is thrown in an upward direction from the top of a building 160 ft high at an initial speed of 30 mi/h, what is its final speed when it hits the ground
*May 21, 2015*

**Organic Chemistry**

Oh, the reactant involved is KOH. I forgot to mention that.
*May 10, 2015*

**Organic Chemistry**

any o-chemists out there? Some help would be greatly appreciated. So I have this compound, it has 5 C's total, a bromine at one end and 2 methyl groups coming off the 3rd C from the bromine and an OH group at the end. like this: Br-CH2-CH(CH3)2-CH2OH. Now I have to come up...
*May 10, 2015*

**chemistry help meee **

okay so I'm given a graph of a melting profile of a macromolecule, it is a sigmoid "s" curve, which states that a protein is cooperative. I have four choices on what the graph will look like if it is uncooperative. 1) Graph 1- straight line with + slope 2) Graph ...
*May 7, 2015*

**math**

Of the 6796 students in one school district, 1537 cannot read up to grade level. Among a sample of 812 of the students from this school district, 211 cannot read up to grade level. Find the sample proportion of students who cannot read up to grade level. A. 0.14 B. 0.26 C. 211...
*April 17, 2015*

**physics**

A centrifuge for separation of sugar crystals in molasses must exert a force of 6 N/g. If the filter drum has a radius of 350 mm, determine the required speed in the revolution per minute I tried the following F = 6 = 10^-3*a a = 6000 = ω^2*r
*April 14, 2015*

**physics**

A centrifuge for separation of sugar crystals in molasses must exert a force of 6 N/g. If the filter drum has a radius of 350 mm, determine the required speed in the revolution per minute I tried the following F = 6 = 10^-3*a a = 6000 = ω^2*r
*April 14, 2015*

**History **

What was the goal of the minimum foundation program for education? A. It integrated whites and blacks int he same school system. B.It improved the quality of white-only education. C. It raised taxes. D. It put more money into black schools. @Writeacher please don't help me...
*March 24, 2015*

**physics**

a 70 kg block rests on the earth's surface. How much energy is required to move the block very far from the earth, ending up at rest again?
*March 22, 2015*

**Math**

V=pi*r*h V=pi*6*12 V=72 pi or roughly 226 ft^3
*March 7, 2015*

**Math**

it comes out as 450 for me in the calculator, 300+90+60
*March 7, 2015*

**Math**

450 Surface Area of a Box: 2lw + 2lh + 2wh
*March 7, 2015*

**Urgent maths homework help**

At a boarding school, in the evening, 9 students always take walks in groups of 3. How can the groups be arranged so that each person walks in a group with every other person exactly once in 4 days? I would like to know whether there is a trick to these type of questions. My ...
*February 21, 2015*

**Introductory Algebra**

the length of a rectangle is 7 meters more than twice the width. the perimeter is 68 meters. solve for length and width. I need this step by step using the blueprint...please.
*February 11, 2015*

**chemistry**

why would dipole moment increase with temperature for a planar molecule? even though those are inversely related...
*February 8, 2015*

**chemistry**

what mass of AgBr is produced when 100.0 mL of 0.150 M AgNO3 is added to 20.0 mL of 1.00 M NaBr?
*January 27, 2015*

**langage arts**

Which of the following passages from the novel is most useful in helping you determine what type of ruler general gage is from Johnny remain? Select all that apply A Sam Adams was so happy his hands shook worse then ever B. He was not brilliant, but he was so tyrant C. His ...
*December 17, 2014*

**Math Question**

Given tan θ = -8/5 and sin θ < 0, find sin θ, cos θ, csc θ, sec θ, and cot θ.
*December 14, 2014*

**math**

0.3 divited by 0.06 is 5. 0.3 goes in to 0.06 5 times
*December 11, 2014*

**capacity problems**

80 buckets of water fill a pond each bucket holds 2litres how much water does the pond hold
*December 6, 2014*

**chemistry**

How many bonds can each atom make without hybridization? B,N, and O
*December 5, 2014*

**Maths**

What side lengths could a rectangle have such that it's area rounds to 20 m squared ( to the nearest 10 )
*November 23, 2014*

**physics**

1) How many seconds does it take a car traveling 40 mph, decelerating at a rate of 7 miles per second, to come to a complete stop? 2) How many feet?
*November 20, 2014*

**programming c++**

write a simple c++ application that displays different varieties of meal. the application must do the following; I. allow a user to choose a meal, ii. prompt the user of the choice made, iii. display the cost of the food.
*November 14, 2014*

**Algebra**

A seismograph 300 km from the epicenter of an earthquake recorded a maximum amplitude of 5.3 x 10^2 um. Find the earthquake's magnitude. Round your answer to one decimal place.
*November 7, 2014*

**social studies**

identify 3 kinds of artifacts and explain what they tell us about ancient people.
*October 28, 2014*

**math**

3/5 + 3/4 round each fraction and estimate the sum. add the two fraction using a common denominator and then round the result. which estimate is closer to the actual answer.
*October 27, 2014*

**Chemistry**

How to convert 24.63cm to nm^2
*October 6, 2014*

**Chemistry**

Report 2 decimal places and appropriate units, the molar mass of steric acid (C17H35COOH). Please help
*October 6, 2014*

**Chemistry**

How many moles of steric acid are contained in 0.25mL of a hexane solution containing 5.4x10^-4 grams of steric acid/L? (Hint: g/L x L = g/ (g/mol)=mol). Please show your work. Please help. Thank you
*October 6, 2014*

**Chemistry**

Report 2 decimal places and appropriate units, the molar mass of steric acid (C17H35COOH). Thank you
*October 6, 2014*

**Chemistry**

How many moles of steric acid are contained in 0.25mL of a hexane solution containing 5.4x10^-4 grams of steric acid/L? (Hint: g/L x L = g/ (g/mol)=mol). Please show your work. Please help. Thank you
*October 6, 2014*

**Chemistry**

I need help with two problems need helps please!! 1) Calculate the surface area in nm^2 of a water solution contained in a watch glass with a diameter of 5.6cm. Remember that the area of a circles is calculate as A=πr2 and diameter= 2r 2) If a molecule of stearic acid ...
*October 6, 2014*

**Algebra**

Find a scalar equation of the plane that contains the given point P=(-3,-3,1)and the given normal vector n = (-1,4,7)
*September 24, 2014*

**Physics**

A gamma ray with 700KeV energy is Compton-Scattered from an electron. Find the energy of the photon scattered at 110 degrees, the energy of the scattered electron, and the recoil angle of the electron.
*September 23, 2014*

**Physics**

If a 6.0keV photon scatters from a fee proton at rest, what is the change in the photon's wavelength if the photon recoils at 90 degrees?
*September 23, 2014*

**Physics**

A television tube operates at 20,000V. What is min wavelength for the continuous x-ray spectrum produced when the electrons hit the phosphor?
*September 23, 2014*

**Physics**

The Stanford Linear Accelerator can accelerate electrons to 50GeV (50x10^9eV). What is the minimum wavelength of photon it can produce by bremsstrahlung? Is this photon still called an x-ray?
*September 23, 2014*

**Physics**

An experimenter finds that no photo-electrons are emitted from tungsten unless the wavelength of light is less than 270nm. Her experiment will require photo-electrons of maximum kinetic energy 2.0eV. what frequency of light should be used to illuminate the tungsten?
*September 23, 2014*

**Physics**

What is the threshold frequency for the photoelectric effect on lithium (phi= 2.93eV)? What is the stopping potential if the wavelength of the incident light is 400nm?
*September 23, 2014*

**Physics**

An FM radio station of frequency 107.7MHz puts out a signal of 50,000W. How many photons/s are emitted?
*September 23, 2014*

**Physics**

White dwarf stars have been observed with a surface temperature as hot as 200,000 o C. What is the wavelength of the maximum intensity produced by this star?
*September 23, 2014*

**Physics**

A body's temperature is increased from 900K to 1900K. By what factor does the total power radiated per unit area increase?
*September 23, 2014*

**Physics**

A gamma ray with 700KeV energy is Compton-Scattered from an electron. Find the energy of the photon scattered at 110 degrees, the energy of the scattered electron, and the recoil angle of the electron.
*September 23, 2014*

**Physics**

If a 6.0keV photon scatters from a fee proton at rest, what is the change in the photon's wavelength if the photon recoils at 90 degrees?
*September 23, 2014*

**Physics**

A television tube operates at 20,000V. What is min wavelength for the continuous x-ray spectrum produced when the electrons hit the phosphor?
*September 23, 2014*

**Physics**

The Stanford Linear Accelerator can accelerate electrons to 50GeV (50x10^9eV). What is the minimum wavelength of photon it can produce by bremsstrahlung? Is this photon still called an x-ray?
*September 23, 2014*

**Physics**

An experimenter finds that no photoelectrons are emitted from tungsten unless the wavelength of light is less than 270nm. Her experiment will require photoelectrons of maximum kinetic energy 2.0eV. what frequency of light should be used to illuminate the tungsten?
*September 23, 2014*

**Physics**

An experimenter finds that no photo-electrons are emitted from tungsten unless the wavelength of light is less than 270nm.
*September 23, 2014*

**Physics**

What is the threshold frequency for the photoelectric effect on lithium (phi= 2.93eV)? What is the stopping potential if the wavelength of the incident light is 400nm?
*September 23, 2014*

**Physics**

An FM radio station of frequency 107.7MHz puts out a signal of 50,000 W.How many photons/s are emitted?
*September 23, 2014*

**Physics**

White dwarf stars have been observed with a surface temperature as hot as 200,000 o C. What is the wavelength of the maximum intensity produced by this star?
*September 23, 2014*

**Physics**

A body's temperature is increased from 900K to 1900K. By what factor does the total power radiated per unit area increase?
*September 23, 2014*

**health**

The spinal cord serves as a conduction pathway for impulses going to and from the ________. A. Lungs B. Liver C. Brain D. Heart
*September 23, 2014*

**Physics**

Calculate the energy needed to accelerate a spaceship of mass 10,000 kg to a speed of 0.3c for intergalactic space exploration. Compare with the projected energy usage of the Earth in a decade~10^22J? well i don't know how to start the problem
*September 14, 2014*

**algerbra**

The participants in a weight-loss class lost the following weights (in pounds) after three weeks of dieting: 1,5,2,1,3,6 Assuming that these weights constitute an entire population, find the standard deviation of the population. Round your answer to at least two decimal places...
*August 27, 2014*

**Health**

D I think
*August 23, 2014*

**Chemistry**

A 2.00g sample of Fe3O4 is reacted with with 8.00g of O2 to produce Fe2O3. a) What mass of Fe2O3 will be produced? b) What mass of Fe2O3 will actually be produced if the percentage yield for reaction is 85% produced?
*August 12, 2014*

**algebra**

P=2L+2W;L=68,W=84
*August 1, 2014*

**algebra**

The sum of two page numbers on facing page of a book is 81. What are the page numbers
*August 1, 2014*

**mathematics**

125,454 dollars take 30% how much is left
*July 29, 2014*

**PSY/410**

Thanks Ms. Sue
*July 9, 2014*

**PSY/410 **

Will someone please check my answer please. Thanks in advance. Match the definitions to the correct theoretical model. 1. ___J__ Experiences as a child affect life. Child is influenced by caretaker but also has a part in development. 2. __F___ 2–3 years of age and the ...
*July 9, 2014*

**PSY/410**

Thanks Ms. Sue
*July 9, 2014*

**PSY/410**

I need help finding information to this question please. I found some information on Modern Psychology but not Abnormal Psychology. Thanks in advance. Create a timeline that displays the development of abnormal psychology. Include at least five to seven main milestones.
*July 9, 2014*

**Chemic**

so how much sulphuric acid ml need and how much water?
*July 8, 2014*