Friday

April 29, 2016
Total # Posts: 128

**AP Chemistry**

Determine the pH of an HF solution with a 4.70x10^-2M and 2.20x10^-2M. I tried this by looking up the Ka and putting it over molarity-ka squared. Am I doing something wrong? Can someone please show me the proper way to solve this problem?
*February 9, 2016*

**science**

what is the velocity of a 0.7 kg ball that has a momentum of 1.4 kg m/s
*January 30, 2016*

**Math**

David and Mike are brothers. David is 33 years old today. This is three times as old as Mike was when David was the age that Mike is today. How old is Mike?
*October 14, 2015*

**health**

How many American adults does OCD affect each year?
*May 14, 2015*

**Chemistry**

What is the percent by mass of NaHCO3 and KCl in the mixture.
*February 15, 2015*

**chemistry**

A buffer solution is made by dissolving 0.45 moles of a weak acid (HA) and 0.13 moles of KOH into 760 mL of solution. What is the pH of this buffer? Ka = 3.3 × 10−6 for HA.
*February 2, 2015*

**physics**

An airplane of mass 1.30 104 kg is moving at 52.0 m/s. The pilot then increases the engine's thrust to 7.00 104 N. The resistive force exerted by air on the airplane has a magnitude of 3.00 104 N.
*November 24, 2014*

**physics**

a hemisphere container is made with the following dimensions. the external diameter of the container is 12 cm. the internal diameter of the container is 6 cm. it is filled with water to the brim. what is the density of the empty container if the total mass of the container ...
*September 2, 2014*

**science**

a hemisphere container is made with the following dimensions. the external diameter of the container is 12 cm. the internal diameter of the container is 6 cm. it is filled with water to the brim. what is the density of the empty container if the total mass of the container ...
*September 2, 2014*

**Science**

A car converts 1000 J of energy from a sample of fuel. 750 J of heat (thermal energy) is produced by the engine, 150 J of heat is produced in the transmission, drive train, etc., and 100 J of work is done to move the car. How efficient was the process of burning fuel for the car?
*August 8, 2014*

**Math**

Helping grandson with math. I would like to know how to do it before he does. "How many different rectangles can be made with a perimeter of 20 units? (Remember, a square is also a rectangle.)"
*May 25, 2014*

**medical coding**

755.01, 755.58, 765.29, 747.10, 745.4, V30.00
*October 15, 2013*

**Physics **

A skater rotates 880 degrees clockwise, stops, and rotates counterclockwise for 340 degrees. What is her angular distance? Angular displacement?
*August 6, 2013*

**Physics**

A block of wood has a mass of 340g .what is its weight ? ( g = 10n kg-1)
*July 14, 2013*

**life orientation**

one environmental or human factor that causes ill health or accidents or disasters within your community or any other community within south Africa. discuss eight ways it can have an impact and five recommendations how to address the problem.
*May 18, 2013*

**us history**

In many ways after the divisiveness and devastation of the Civil War, the United States searched for order economically, politically, geographically, socially and racially. Select one of these areas, or suggest another, and make a case for the reasons why it was the most vital...
*December 5, 2012*

**chemistry**

The orbitals 2s and 3p would be the same shape as the 1s and 2p, but would be larger in size.
*December 1, 2012*

**algebra**

steps to (.15x)+(-.3x)=
*November 11, 2012*

**Math**

A box with an open top is to be constructed from a rectangular piece of cardboard with dimensions 12 in by 12 in by cutting out equal squares of side x at each corner and then folding up the sides as in the figure. Express the volume V of the box as a function of x.
*September 10, 2012*

**Math**

Find an expression for the function. Top half of the circle: x^2+(y-2)^2=4.
*September 10, 2012*

**Math**

A cylindrical can with both a top and bottom has the same surface area as a cube with edge 50mm. The height of the can if 6cm. Find the radius of the can to the nearest thousandth.
*September 3, 2012*

**Chemistry**

Rank the following from most polar to least polar (aspirin, caffeine, ibuprofen, acetaminophen): I am getting caffeine>acetaminophen>aspirin>ibuprofen. Is that correct?
*September 2, 2012*

**Math**

Use the Intermediate Value Theorem to show that there is a root of the given equation in the specified interval. cos x = x. How do I begin this problem? According to the theorem, a=0, b=1 and N=x?
*September 2, 2012*

**Math**

Use the Intermediate Value Theorem to show that there is a root of the given equation in the specified interval. x^4+x-3=0, interval (1,2). According the to theorem, I found that a is 1, b is 2 and N is 0. f(1)= 2 and f(2) = 17. Is the root (1.16,0)?
*September 1, 2012*

**Math**

Use a graph to find a number delta such that if abs(x-pi/4) < delta then abs(tanx-1) < 0.2. I understand that the epsilon is 0.2. But what step do I take next? How do I solve the problem?
*September 1, 2012*

**Math**

Prove that lim (x->0) x^4 cos 2/x = 0.
*September 1, 2012*

**Math**

Answer check please: Consider the circle (x-3)^2 + (y+1)^2 = 169. The point (15,4) is on the circle. Find an equation for the line that is tangent to the circle at this point. I got y= 5/12x-9/4.
*August 26, 2012*

**Math**

An oil tank is the shape of an inverted right circular cone with the pointed end down. The tank is 15 feet tall and is 12 feet in diameter at the top. At 1:00pm, the tank has oil 5 feet deep in it. Oil is pouring in at 5 cubic feet per minute. To the nearest minutes, at what ...
*August 26, 2012*

**Math**

A truck tire with a diameter of 36 in is rolling over level ground spinning at 11 rotations/second. If the speed limit is 55 miles per hour and the penalty is $20 per hour over the speed limit, should the driver be fined and if so, how much?
*August 26, 2012*

**Math**

An isosceles triangle has its vertex at the origin and the ends of its base on the parabola y=9-x^2. Express the area of the triangle as a function of the length of its base. Assume its base lies above the x-axis.
*August 26, 2012*

**Chemistry**

How many milliliters of a .5M HNO3 (aq) is needed to completely neutralize 100mL of a 0.10M KOH (aq)?
*May 30, 2012*

**algebra**

a bank teller has 52 $5 and $10 bills in her cash drawer. the value of the bills is $460. how many $5 bills are there?
*April 18, 2012*

**chemistry**

Which of the following pairs can be used to prepare a buffer? (select all that can apply) a. HCl/NaCl b. HF/KF c. NH3/NH4Cl d. HNO3/HNO2 e. NaNO2/HNO3 can you also please explain how they form a buffer? thank you
*April 12, 2012*

**math**

Jamal buys 59 stickers. Stickers come in packs of 5 or 8. How many packs of 5 stickers does Jamal buy? 8 stickers?
*March 7, 2012*

**Biology**

Which of the following would be the most sigificant between mitosis and meiosis? A. Chromosomes are duplicated before mitosis B. Meiosis is not followed by cytokinesis C. Homologous Pairs of chromosomes are split up in meiosis. D. Crossing over occurs in mitosis. So far i got ...
*March 6, 2012*

**Math**

Greta said that the product of two prime numbers must also be a prime number. Joan disagreed. Who is correct?
*December 6, 2011*

**Math**

Thank you so much!
*December 5, 2011*

**Math**

There are 189 students in the band. The difference between the number of boys and the number of girls is 27. How many boys and girls each are in the band?
*December 5, 2011*

**Math**

Thank you so much !!!!
*December 5, 2011*

**Math**

Jun-Jee either ran 5 or 7 miles each day for 30 consecutive days. His total mileage during this period was 166> How many days did he run 5 miles? How many days did he run 7 miles?
*December 5, 2011*

**math**

Thank you
*December 5, 2011*

**math**

If there are 264 students in a school and there are 84 eighth graders and There are 22 fewer seventh graders than sixth graders. Then which grade has the most students and how many students are there.
*December 5, 2011*

**chemistry**

CH4 + 2O2 ---> CO2 + 2H2O Delta H H2O= -285.8 kJ/mole Delta H CO2= -393.3 kJ/mole What is the standard heat of formation of methane, Delta H CH4, as calculated from the data above
*November 18, 2011*

**trig**

5. If the angles X and Y each measure between 0° and 90°, and if sinX = cosY, what is the sum of the measures of the angles X and Y?
*November 17, 2011*

**geometry **

How would you write that line segment PK has equal length with line segment OQ?
*November 14, 2011*

**geometry**

Thank you:) I got x=12 too but I wanted to make sure I was correct.
*November 14, 2011*

**geometry**

If FD=4x-27, and SG is congruent to FD and SG=2x-3, Then whais the length of SG?
*November 14, 2011*

**algebra**

You could demonstrate the process with an example by replacing the equal sign in the example with an inequality by using the less than or greater than sign (< or >) Then solve the inequality by your example. :)
*November 14, 2011*

**Statisitcs**

since the mean is a parameter of interest, it is a better estimate.
*October 6, 2011*

**Animal Skeletal and Muscular Systems**

wich of the fallowing muscles are used when breathing?
*September 21, 2011*

**algebra**

-rs^3-r^3s=
*September 6, 2011*

**chemistry**

Suppose the following: HO-C(H2)-C(H2)-OH + 2 HI --> I-C(H2)-C(H2)-I + water How many mL of the first compound* are needed to react with 9.3 grams of HI? (The density of the first compound is A = 1.11 g/mL) *by first compound, i mean HO-C(H2)-C(H2)-OH
*September 2, 2011*

**pre cal 2 **

solve the equation 4cos^2x-1=0
*July 24, 2011*

**pre cal 2**

verify the identity tanx times cotx/cosx=secx
*July 24, 2011*

**pre cal 2**

find the exact solutions in the interval [0,2pi), sin4x=-2sin2x
*July 24, 2011*

**Math**

Thankyou Sir for helping me. I am studying for my tcap exam and some of the stuff on the test we didnt have time to cover because it snowed so much and we couldnt go to school.I think I no what I am looking for now. You have been a bunch of help.
*April 9, 2011*

**Math**

What addition property can you use to find the missing number? 8+(6+5)=8+(5+_)
*April 9, 2011*

**us history**

My paper is on 3 reasons I would stay and fight 1. with so many men being sick or dying, I will stay and fight 2. freedom doesn't come cheap and anything of value is worth fighting for 3. the Congressional Committee that G. Washington brought over to Valley Forge will now ...
*March 16, 2011*

**us history**

I'm writing a paper about re-enlisting during the American Revolution, even though I'm miserable with the sick and dying all around me. I need to come up with a good grabber to start my paper with. Can you help?
*March 16, 2011*

**Statistics**

You need a double integral. integral from 10 to 10.85 integral from 10.07 to 10.39 ( only one changed because it is asking for a single pipe.) integrate the function 1/(10.85-10)^2
*March 5, 2011*

**Economics**

How would a communist economy react to social and technological changes? What is the role of nature in a communist economy? I can't find any information on these subjects. Could someone please help me? Thanks so much
*February 11, 2011*

**hcs/335**

I do not understand it either. I cannot give the answer because I really don't know where to start. My confusion is in the culture, does it mean the "organizational culture", which could be the philosophies, values, etc... or the culture of the people in the ...
*February 9, 2011*

**math**

1.Robin has a certain number of dimes in his pocket. If the dimes were pennies, he would have $1.08 less than he has now. How many dimes does he have in his pocket?
*January 27, 2011*

**math**

1.Robin has a certain number of dimes in his pocket. If the dimes were pennies, he would have $1.08 less than he has now. How many dimes does he have in his pocket?
*January 27, 2011*

**Math**

A class has 12 students. In how many different ways can the students be put into lab groups consisting of 3 students in each group. The answer in the book is 369600. But I do not understand how they got this answer.
*January 26, 2011*

**Math percentages**

I have to compare two amounts given in percent. Last year, 80% of a cafe's sales were coffee; this year only 20% of the cafe's sales are coffee. How much has the percent of coffee sales changed over the past year. Is the answer simply down by 60% or is it more ...
*January 10, 2011*

**college**

6.25 is correct
*December 16, 2010*

**Physics**

A 7.0 kg bowling ball moves at 2.40 m/s. How fast must a 2.60 g Ping-Pong ball move so that the two balls have the same kinetic energy?
*December 10, 2010*

**physics**

A 726 kg car travels from Boone to Blowing Rock along US321. How much working is needed to keep the car traveling at a constant speed of 21.8 m/s around a curve of radius 28.4 m?
*December 5, 2010*

**Physical Chemistry**

The equilibrium constant for a reaction was measured at several temperatures and the data plotted at right. The slope and y-intercept of the plot are +3.25 kK and -4.04, respectively. Calculate ΔrH(std), ΔrS(std), and ΔrG(std) using this information.
*November 10, 2010*

**Physical Chemistry**

A 100 amino acid folded protein (F) is in equilibrium with it’s unfolded (U) (or denatured) form. Let ΔrH(std) =+347 kJ mol-1 and ΔrS(std) =-1010 J K-1 mol-1 for the equilibrium (F U) at 25℃. (a) Calculate the concentration of protein in each form if the ...
*November 10, 2010*

**Physical Chemistry**

Calculate the standard reaction Gibbs energy of the oxidation of ammonia to nitric oxide according to the equation 4 NH3g) + 5O2(g) → 4 No(g) + 6 H2O(g).
*November 10, 2010*

**physical chemistry**

Calculate the equilibrium constant (K) for the ammonia synthesis reaction at 25°C and show how K is related to the partial pressures of the species at equilibrium. Consider that the overall pressure is low enough for the gases to be treated as perfect. N2(g) + 3H2(g) ->...
*November 10, 2010*

**math**

If the ratio of onions to cilantro is 4:3 and I'm using 2/3 cup of onions, how much cilantro will I need?
*November 8, 2010*

**Math**

Fireworks are fired at an angle of 82degrees with the horizontal. They are expected to explode about 100 m in the air, 4.8 secs after they are fired. What is the initial velocity of a shell fired from ground level. I think I have to find the vertical and horizontal components ...
*November 1, 2010*

**Physics**

An artillery shell is fired with an initial velocity of 300 m/s at 65.0° above the horizontal. To clear an avalanche, it explodes on a mountainside 37.5 s after firing. What are the x and y components of the shell where it explodes, relative to its firing point? x = ...
*October 20, 2010*

**Physics**

A student stands at the edge of a cliff and throws a stone horizontally over the edge with a speed of 21.0 m/s. The cliff is h = 60.0 m above a flat horizontal beach. A)How long after being released does the stone strike the beach below the cliff? B)With what speed and angle ...
*October 20, 2010*

**college**

need help with miscrosoft excel 2010 spreadsheet IS 160
*September 1, 2010*

**science**

Provide specific examples from the Bridger Teton video as you defend your position.
*June 17, 2010*

**math**

a rabbit climb up a flight of 10 stairs and can only hop 1 or 2 steps each time. he never hops down, only up. How many ways can the rabbit hop up the flight of 10 steps?
*June 7, 2010*

**biology**

how is emigration and immigration not important factors when studying global human population growth?
*May 25, 2010*

**algebra**

list all the possible rational zeros of f using the rational zero theorem. then find all the zeros of the function. 1. f(x)=x^2-6x+5 2. f(x)=x^3+x^2-10x+8
*May 23, 2010*

**biology**

why is it important to understand challenges in a species' environment in order to understand the species' evolution? Relate your answer to what Darwin referred ti as "the struggle for survival".
*May 22, 2010*

**english**

In the book, When the Legends Die, what does it mean when Tom draws the deer in the dirt?
*April 19, 2010*

**social civics**

the three basic types of government: mayor-council plan, the commission, and the manger-council plan. give at least one strength and one weakness for them . and size of city where most effective thanks alot i cannot not seem to find this in my book
*April 9, 2010*

**college**

What are the three most important points you think a group of people must keep in mind when working collaboratively on a writing project? Why? Support your response with references to readings and personal experiences.
*April 5, 2010*

**Math**

Thanks.
*November 24, 2009*

**Math**

I'm having trouble with reciprocal functions. If a graph of a reciprocal function is given, how do you find its equation? Any help would be really appreciated.
*November 24, 2009*

**Algebra**

I need this question put into an equation. I have been working on this forever and cannot figure out! Please explain what you did. Thanks so much for your time! Mark sold 105 tickets for the basketball game. Each adults ticket cost $2.50 and each child's ticket cost $1.10...
*October 14, 2009*

**Biology**

1. A famous scientist once said that wherever in the universe life exists, some of those life-forms must be colored. Why would the scientist make such a statement? 2. One of the accessory pigments used in photosynthesis is beta-carotene, a carotenoid found in high ...
*October 12, 2009*

**history**

can u please give me a site tht will have a short but an informative article on the English Reformation? thnks
*May 25, 2009*

**Physics**

Thanks!
*April 11, 2009*

**Physics**

If a ball is sliding along a frictionless horizontal surface is the total work being done on the ball zero? I think so because there is no mention of applied force. Am I correct? P.S. On this holiday weekend, I want to send a BIG THANK YOU to all the teachers who very ...
*April 11, 2009*

**Physics**

Thank you very much!
*April 6, 2009*

**Physics**

Thanks. Is this the only way to calculate because in our lesson we only learned the formula for work =fd? We've haven't done KE yet.
*April 6, 2009*

**Physics**

I don't know where to start with this one. "Find the work done accelerating a 2 kg box from 2m/s to 3 m/s." Can't find acceleration because I don't know time. In fact, I don't see how any of the kinematic equations can help me out to find either ...
*April 6, 2009*

**Physics**

Thank you so much!!!
*April 6, 2009*

**Physics**

I have a follow-up to my question at 4:10 about work because I still can't figure it out. F-F(friction)=ma F-F(friction)=2*3 F-2.5=2*3 F=2*3 + 2.5 W=Fd W=(2*3 + 2.5)4 Distributing the "4" I get W=2*3*4 +2.5*4 Please help in pointing out where I have gone wrong. ...
*April 6, 2009*

**Physics**

Help!I'm really lost on this one.
*April 6, 2009*