Monday

November 30, 2015
Total # Posts: 5,167

**Physics**

A particular task exposes the operator to alpha radiation at an average dose of 200 ìGy each time the task is performed. If the company needs the task performed once per day over a 250-day working year and the maximum occupational dose limit is 20mSv per year, how many ...
*October 1, 2013*

**physics**

This is an example question which I have the answer to but can not seem to get the same answer through my workings, any help with the equation would be great. A particular task exposes the operator to alpha radiation at an average dose of 200 ìGy each time the task is ...
*October 1, 2013*

**Math**

Emma is 5 years older than 6 times beth's age. If Emma is 29 years old how old is Beth?
*October 1, 2013*

**check my work on derivatives**

Can someone check my work? So, I took the derivative of (1-x^2)/((1+x^2)^2) I used the quotient rule ((2x((1+x^2)^2)-2((1+x^2)^2)(2x)(1-x^2))) / ((1+x^2)^4) Then I simplified it (2x+2x^2 - 4x((1+x^2)^2)(1-x^2)) /((1+x^2)^4) Then I simplified by factoring out some numbers 2x(x^...
*September 30, 2013*

**physics**

A motorist travelling at 82 km/hr is being chased by a police car at 121 km/hr. If the police car starts from 4.0 km back, how long does it take to catch the motorist? Leave time in hours.
*September 30, 2013*

**geometry**

what is a concave polygon using the classify and differentiate method
*September 26, 2013*

**Chemistry**

A volume of 60.0mL of aqueous potassium hydroxide (KOH ) was titrated against a standard solution of sulfuric acid (H 2 SO 4 ). What was the molarity of the KOH solution if 25.7mL of 1.50 M H 2 SO 4 was needed? The equation is 2KOH(aq)+H 2 SO 4 (aq)¨K 2 SO 4 (aq)+2H ...
*September 26, 2013*

**History (chronological order)**

1,2,4,3
*September 25, 2013*

**Physics 2 College Level**

A cylinder is closed at both ends and has insulating walls. It is divided into two compartments by an insulating piston that is perpendicular to the axis of the cylinder as shown in Figure a. Each compartment contains 1.00 mol of oxygen that behaves as an ideal gas with γ...
*September 17, 2013*

**grammar fast plz**

Well then it will be just freshmen. So you would say "...YOU, the freshmen-class of 2017.
*September 17, 2013*

**Chemistry**

We did a flame test today to see what substances produce what colors when burned. Can you please explain... Why each of the different elements have a different atomic emission spectrum? Would the flame tests be useful for detecting individual elements present in a mixture of ...
*September 17, 2013*

**Math urgent**

Oh I understand now. Thank you so much!
*September 16, 2013*

**Math urgent**

Thank you! Could you please show your work to how you got to 1/10? It would be easier to explain to my class.
*September 16, 2013*

**Math urgent**

What is 4.1 repeating written as a fraction? I don't know if it should be written over 100 or over 10.
*September 16, 2013*

**Chemistry**

Orange light has a frequency of 4.8 x 10^14 s^ -1. What is the energy of one quantum of orange light?
*September 16, 2013*

**Economic**

Who has an unlimited checking account with the US Treasurer that enables them to write all the checks they want without regard to having funds in the bank?
*September 14, 2013*

**Science**

Helium doesn't react with any other substance. Is it accurate to say that helium has no chemical properties? Explain. Please help because I'm not sure of the answer. Thank you.
*September 13, 2013*

**Science**

*IM SORRY I MEANT SCIENCE FOR THE SUBJECT.
*September 13, 2013*

**History**

Helium doesn't react with any other substance. Is it accurate to say that helium has no chemical properties? Explain. Please help because I'm not sure of the answer. Thank you.
*September 13, 2013*

**AP Calculus**

I asked this yesterday and someone answered. but i didn't understand the explanation.. Two circles of radius 4 are tangent to the graph of y^2=4x at the point (1,2). Find equations of these two circles. I got (x-1)^2+(y-2)^2=16 and (x-4.36)^2+(y+1.36)^2=16
*September 12, 2013*

**Math**

plug in 4 for x, and -3 for y. 4-4(-3)/2 4+12/2 16/2 8
*September 12, 2013*

**math**

At 4 pm, Jack who is 6 ft tall cast a shadow that is 4 1/2 ft long. At the same time, a nearby free cast a shadow that is 12 ft long, how tall is the tree?
*September 12, 2013*

**AP Calculus**

A projectile fired upward from ground level is to reach a maximum height of 1,600 feet. What is its initial velocity?
*September 11, 2013*

**AP Calculus**

Two circles of radius 4 are tangent to the graph of y^2=4x at the point (1,2). Find equations of these two circles. I found the derivative of y^2=4x, but i don't know what to do next!
*September 11, 2013*

**Computer Science**

The array represents a map with coins, and the integers represent a row and column location of a coin gatherer. The gatherer is greedy and lazy when deciding to which adjacent location (either up, down, left, right) to move next. It’s greedy because it moves to the ...
*September 8, 2013*

**Physics**

A firefighter 41.8m away from a burning building, directs Zach stream of water from a ground level fire hose at an angle of 33.0 degrees above the horizontal . If the speed of the streams it leaves the hose is 42.7m/s, at what height will the stream of water hit the building
*September 8, 2013*

**Physics**

Suppose a single electron orbits about a nucleus containing two protons (+2e), as would be the case for a helium atom from which one of the two naturally occurring electrons is removed. The radius of the orbit is 2.65 10-11 m. Determine the magnitude of the electron's ...
*September 8, 2013*

**Physics**

A circular surface with a radius of 0.058 m is exposed to a uniform external electric field of magnitude 1.49 104 N/C. The electric flux through the surface is 74 N · m2/C. What is the angle between the direction of the electric field and the normal to the surface?
*September 8, 2013*

**Physics**

In the rectangle in the drawing, a charge is to be placed at the empty corner to make the net force on the charge at corner A point along the vertical direction. What charge (magnitude and algebraic sign) must be placed at the empty corner? (the rectangle has +3 uC charges in ...
*September 8, 2013*

**Physics**

Suppose a single electron orbits about a nucleus containing two protons (+2e), as would be the case for a helium atom from which one of the two naturally occurring electrons is removed. The radius of the orbit is 2.65 10-11 m. Determine the magnitude of the electron's ...
*September 8, 2013*

**Math**

A projectile is fired with an initial velocity of v0 feet per second. The projectile can be pictured as being fired from the origin into the first quadrant, making an angle O with the positive x-axis. If there is no air resistance, then at t seconds the coordinates of the ...
*September 8, 2013*

**Physics**

Suppose a single electron orbits about a nucleus containing two protons (+2e), as would be the case for a helium atom from which one of the two naturally occurring electrons is removed. The radius of the orbit is 2.65 10-11 m. Determine the magnitude of the electron's ...
*September 6, 2013*

**Physics**

A circular surface with a radius of 0.058 m is exposed to a uniform external electric field of magnitude 1.49 104 N/C. The electric flux through the surface is 74 N · m2/C. What is the angle between the direction of the electric field and the normal to the surface?
*September 6, 2013*

**physics**

A is the bottom left corner. The empty corner is the top right corner.
*September 6, 2013*

**physics**

In the rectangle in the drawing, a charge is to be placed at the empty corner to make the net force on the charge at corner A point along the vertical direction. What charge (magnitude and algebraic sign) must be placed at the empty corner? (the rectangle has +3 uC charges in ...
*September 6, 2013*

**Physics**

Two point charges are fixed on the y axis: a negative point charge q1 = -26 µC at y1 = +0.21 m and a positive point charge q2 at y2 = +0.30 m. A third point charge q = +8.5 µC is fixed at the origin. The net electrostatic force exerted on the charge q by the other ...
*September 6, 2013*

**Physics**

A circular surface with a radius of 0.058 m is exposed to a uniform external electric field of magnitude 1.49 104 N/C. The electric flux through the surface is 74 N · m2/C. What is the angle between the direction of the electric field and the normal to the surface?
*September 6, 2013*

**Physics**

A circular surface with a radius of 0.058 m is exposed to a uniform external electric field of magnitude 1.49 104 N/C. The electric flux through the surface is 74 N · m2/C. What is the angle between the direction of the electric field and the normal to the surface?
*September 6, 2013*

**Physics**

The drawing shows a positive point charge +q1, a second point charge q2 that may be positive or negative, and a spot labeled P, all on the same straight line. The distance d between the two charges is the same as the distance between q1 and the spot P. With q2 present, the ...
*September 6, 2013*

**Science**

Outline a step-by-step method for determining the density of a baseball. Please help with this too! Thanks
*August 31, 2013*

**Science**

Estimate the length of a baseball bat and mass of a baseball in SI units. How can you check how close your estimates are? Please help! Thank you
*August 31, 2013*

**Physics**

When point charges q1=+8.4uC and q2=+5.6uC are brought near each other, each experiences a repulsive force of magnitude 0.66N. Determine the distance between the charges.
*August 28, 2013*

**Physics**

When point charges q1=+8.4uC and q2=+5.6uC are brought near each other, each experiences a repulsive force of magnitude 0.66N. Determine the distance between the charges.
*August 28, 2013*

**Physics**

When point charges q1=+8.4uC and q2=+5.6uC are brought near each other, each experiences a repulsive force of magnitude 0.66N. Determine the distance between the charges.
*August 28, 2013*

**Physics**

Displacement vector A points due east and has a magnitude of 2.26 km. Displacement vector B points due north and has a magnitude of 2.62 km. Displacement vector C points due west and has a magnitude of 2.6 km. Displacement vector D points due south and has a magnitude of 2.6 ...
*August 26, 2013*

**Maths **

Heather loves roses.In her rose garden she has half as many pink roses as red,and four times as many red ones as white.There are 37 roses that are either yellow or white.Twenty are yellow.How many roses are in Heather's garden? Help me out please anyone
*August 24, 2013*

**Maths**

Twenty-four ladybirds were sitting at various places around the garden.One sixth of the ladybirds flew away to settle in the garden.Half of the remaining ladybirds sat on a yellow sunflower.Then half of those on the sunflower flew onto a fence post.There were no ladybirds on ...
*August 24, 2013*

**Maths**

Twenty-four ladybirds were sitting at various places around the garden.One sixth of the ladybirds flew away to settle in the garden.Half of the remaining ladybirds sat on a yellow sunflower.Then half of those on the sunflower flew onto a fence post.There were no ladybirds on ...
*August 24, 2013*

**Math**

Let F(x)= X^2+ 5 and G9x)= (x+1) / (x-1). Find (a) F-3G and (b) F(g(x))
*August 22, 2013*

**Math**

I really want to understand factoring, and I have a problem and the answer but I don't understand the steps to getting an answer. 3x^5-12^4+18x^3
*August 22, 2013*

**Biology (Science)**

Which of the following is not true about a hypothesis? 1) Previous knowledge can help support it. 2) It is a tentative explanation. 3) It can be proven to be false. 4) It must be testable to be useful. 5) It can be proven to be true. I know for sure that 2 and 4 is not the ...
*August 21, 2013*

**Biology (Science)**

John uses mechanical "predators" to approach frogs at a pond shore, and he records the distance between predator and frog as the frogs jump. (PEER REVIEW) On a walk around pond John sees that small frogs on the shore only allow him to get within 5 feet before jumping...
*August 21, 2013*

**Math**

Find an equation of the tangent line to the circle x^2+y^2=25 at the point (4,-3)
*August 20, 2013*

**MAth**

Is this undefined?
*August 20, 2013*

**MAth **

find equation of line which passes through the points (5,7) and (5,-8).
*August 20, 2013*

**Math**

150 x .20 = 30 30 x $6 = $ 180
*August 20, 2013*

**leadership**

In your leadership model, what are the a leader's most important task? What are the core values that your leadership model emphasized?
*August 15, 2013*

**leadership**

what are the core values that your leadership model emphasizes? In what ways does my leadership model reflect existing scholarship on leadership and in what ways is my approach unique to me? what barriers and opportunities exist towards the implementation of my personal ...
*August 15, 2013*

**chemistry**

no im wrong, the ph will not decrease.
*August 13, 2013*

**chemistry**

Can the ph of a buffer solution of potassium hydroxide decrease when exposed to air overnight? I'm pretty sure the answer is yes
*August 13, 2013*

**Chemistry**

If you have a di or polyprotic buffer state below whether you see evidence of this in the form of your pH curve. If you do not see evidence of this, explain why this should be the case Wouldn't you see evidence of a di or polyprotic buffer if there are multiple ...
*August 13, 2013*

**physics**

A hot-air balloon is rising upward with a constant speed of 2.80 m/s. When the balloon is 9.48 m above the ground, the balloonist accidentally drops a compass over the side of the balloon. How much time elapses before the compass hits the ground?
*August 13, 2013*

**chemistry**

I do mean spilled, thanks.
*August 7, 2013*

**chemistry**

That is excellent thank you. Now you have given me the answer working through it myself makes a lot more sense. Can you help me with the one below as well. A 25.0 mL solution of HCl has been spilt. It took 21.8 mL of saturated 2.5 M NaOH to neutralise the acid. What was the ...
*August 7, 2013*

**chemistry**

Can one calculate the number of moles of air? If so, calculate the number of moles in 1 kg of air (making sure your calculation, units and assumptions are fully explained); If not, explain why it is not possible to calculate the number of moles of air.
*August 7, 2013*

**chemistry**

A 25.0 mL solution of HCl has been spilt. It took 21.8 mL of saturated 2.5 M NaOH to neutralise the acid. What was the molar concentration of the acid?
*August 7, 2013*

**maths**

Determine the acute angle between the line passing through the points A(-2;1/5) and B(0;1) and the line passing through the points C(1;0) and D(-2;6)
*August 6, 2013*

**Physics**

Why is it highly unlikely to find an ion with a charge less than -4 or greater than +4? I need examples of different types of ions and evidence to support the logic using the concepts of ionization energy and electronegativity.
*August 6, 2013*

**Math**

during the warranty period, 6% of their computers are returned because they have defective keyboards, 5% are returned because they have defective disk drives, and 1% are returned because both the keyboard and the disk drive are defective. What is the probability that a ...
*July 27, 2013*

**math**

sorry,i 'm not understand the number 4,4,4 either
*July 27, 2013*

**math**

complete the pattern : 1/2 , 3/4 , 1 , 4 , 4 , 4
*July 27, 2013*

**math**

it's the right answers,that's why i cannot figure it out
*July 27, 2013*

**math**

the iceman found recently in a glacier was a first thought to be about 5300 years old.Roughly when did he have his 14th birthday?2700bc,300bc,3700bc,5300bc or 7300bc
*July 27, 2013*

**math**

i don't understand what is x of y alone ,
*July 27, 2013*

**math**

if a number x is 10%of y and z,and z is 3 times of y.What % is x of y alone? 1)3.3% 2)2.5% 3)5% 4)4%
*July 27, 2013*

**math**

complete the pattern:50,20,8,4,4,4.
*July 23, 2013*

**Spain History**

I'm doing a survey for my class to get opinions to see which side people favored the most, the Nationalists or the Republicans? I have interviewed the people I know but I'm still lacking.
*July 23, 2013*

**Spain History**

Which side would you support in the Spanish Civil War and Why?
*July 23, 2013*

**world geography**

Why are some bodies of water in Russia unnavigable for part of the year? They are frozen. They are too shallow. They are too swift. They contain chernozem.
*July 22, 2013*

**math**

would u please explain,thanks
*July 21, 2013*

**math**

a taut wire of length'w'emits a single note when plucked.if it were half as long it would emit the same note but one octave higher.how long should the same wire be to emit the same note but one octave lower?which gives the biggest answer?1)2.3x8 2)3.4x7 3)4.5x6 4)5.6x5...
*July 21, 2013*

**math**

in the number 0.123451234512345......(recurring)what is the 1992th digit after the decimal point
*July 21, 2013*

**math**

when tessa and fatima run a 100 metre race,tessa wins by 10m.then they repeat the race,this time with tessa starting 11m behind the starting line.if both girls run at the same speed as efore,what would be the expected result?
*July 21, 2013*

**Chemistry 3A**

An aqueous solution contains the ions B, C, and D that are in equilibrium with one another according to the reaction B (aq) + C (aq) ->/<- D (aq) A certain amount of water is added so as to double the volume of this solution, while keeping the temperature and the ...
*July 21, 2013*

**math**

A GARDEN places some lilies in a pond.he does this on the first day of the month of september.the lilies double in volume every day until on the last day of the month,the pool is full.on what day of the month was the pool half full of lilies?
*July 21, 2013*

**math**

thanks,but what is 3^2,is it 3time 2 or square root of 3
*July 20, 2013*

**math**

2 people start off to work directly away from each other.they each walk for 4 kms then turn directly to their right and walk for another 3 kms.how far apart are they
*July 20, 2013*

**math**

5 people measured a metal bar using the same measuing instrument,but each read the scale to a different level of accuracy.their 5 answers are show below.4 of them are correct(to the chosen level of accuracy),but one is not.which is the odd one out?1)244mm 2)243mm 3)243.7mm 4)...
*July 20, 2013*

**math**

a quiz has 25 questions with 4points awarded for each correct answer and 1 point deducted for each incorrect answer,with zero for each question omitted.John scores 77points.how many questions did he omit?
*July 20, 2013*

**math**

as a regular customer in my favourite restaurant,i get 10%discount.but to the cost of the meal must be +17.5%gstand 12%service charge.if the %are to be worked out in turn(which each%-addition or discount-being on the previous answer),which order of working leaves me the least ...
*July 20, 2013*

**math**

it takes 3weeks to build a large garage.if it takes 2/3 of a week to construct the frame and 5/4 of a week to put the roof on.how much time is spent on the rest of the construction?
*July 20, 2013*

**english**

“Boys don’t cook.” What type of rhetorical device or fallacy is this? :“…what are you doing in those overalls? You should be in a dress and camisole, young lady!” what type of rhetorical device or fallacy is this?
*July 19, 2013*

**english**

The older you grow the more of it you’ll see. The one place where a man ought to get a square deal is in a courtroom, be he any color of the rainbow, but people have a way of carrying their resentments right into a jury box. As you grow older, you’ll see white men ...
*July 19, 2013*

**english**

"There's four kinds of folks in the world. There's the ordinary kind, like us and the neighbours, there's the kind like the Cunningham's out in the woods, the kind like the Ewell's down at the dump, and the Negroes." what rhetorical device or ...
*July 19, 2013*

**english**

to kill a mockingbird movie analysis question. 1) how does the lack of eye contact show Mayella is lying? Why is she lying? How does this show racism?How is this significant to the film? analysis further toward the so what factor. Thanks
*July 18, 2013*

**psy**

suppose you wanted to do research on how best to gradually charge the behavior of a fearful child. Which of the following theorist are you likely to come across in your resarch
*July 15, 2013*

**Math**

Simplify the complex fraction: [(4/(x-5))+(2/(x+2))]/ [((2x)/(x^2-3x-10))+3]
*July 12, 2013*

**Social Studies**

It can be said that one of the greatest contributions of the Moors was religious tolerance. Do you believe that is true? If so, why is it then that some people view Muslim culture to be a culture of intolerance?
*July 10, 2013*

**math**

OMG I CAN NOT get this !!!! Purchase price of article = $495 Down payment = $50 Number of payments = 36 True annual interest rate = 18% Monthly payment amount = $ The formula is I= 2YC ________ M(N+1) y = the number of payments made in a year. m = the amount financed or how ...
*July 10, 2013*