Wednesday

August 20, 2014

August 20, 2014

Total # Posts: 3,838

**chemistry**

gaseous hydrogen and fluorine combine in the reaction above to form hydrogen fluoride with an enthalpy change of -540kJ. What is the value of the heat of formation of HF(g)
*February 17, 2013*

**Physics 1**

A taut string connects a 5-kg crate to a 12-kg crate (see figure below). The coefficient of static friction between the smaller crate and the floor is 0.573; the coefficient of static friction between the larger crate and the floor is 0.443. Find the minimum horizontal force ...
*February 16, 2013*

**Science**

Can you please tell me the effects of human activities on ecosystems. Example Human Activity and Consequences....
*February 14, 2013*

**microeconomics **

1. Market demand is given as QD = 250 – 0.5P. Market supply is given as QS = 2P. In a perfectly competitive equilibrium, what will be the value of consumer surplus? a.$10 000 b.$20 000 c.$40 000 d.$80 000 2. Market demand is given as QD = 250 – 0.5P. Market supply is...
*February 13, 2013*

**microeconomics**

1. Suppose that an increase in the price of carrots from $1.20 to $1.40 per pound raises the amount of carrots that carrot farmers produce from 1.2 million pounds to 1.6 million pounds. Using the midpoint method, what would be the elasticity of supply? a. 0.50 b. 1.86 c. 0.54 ...
*February 13, 2013*

**Pre-Calculus**

Determine the equation of a line that passes through (2,2) and is parallel to the line tangent to y=3x^3-2x at (-1,5)?
*February 12, 2013*

**Math**

What is 9/25,35/100,and 2/5 in order from greatest to least
*February 12, 2013*

**physics**

If a 0.5kg toy car is rolling down a hill with a velocity of 0.8m.s, what is the car's momentum?
*February 11, 2013*

**math**

This year Martin is twice as old as his sister. If Martin is 12 years old then how old will his sister be next year
*February 10, 2013*

**math**

Use the Pythagorean Theorem to find the missing side length. someone please tell me what the Pythagorean Theorem is?
*February 7, 2013*

**Chemistry**

Equation: 3CaCl2 (aq) + 2 Na3PO4 (aq) → Ca3(PO4)2 (s) + 6 NaCl (aq) How many grams of Ca3(PO4)2 are formed when 450.0 g NaCl are formed in the reaction? please show steps, please
*February 6, 2013*

**Chemistry**

Heres a balanced equation: Na2CO3(aq)+2AgNO3 (aq) --> 2NaNO3(aq)+Ag2CO3 (s) From this equation, 10 mL of AgNO3 in this contains 34 grams of AgNO3. Calculate the grams of solid product, Ag2CO3. Part 2: 10 mL of Na2CO3 in this experiment contains 21 grams of Na2CO3. ...
*February 6, 2013*

**math**

At the time of the oil spill, the price of gasoline was 2.75 per gallon. Estimate how many dollars in gasoline is being lost per day as a result of the spill.- 2,000,000 gallons is lost per day.
*February 6, 2013*

**Math**

The greatest loss rate estimates are 4,200,000 gallons per day since the start of the spill, but after 44 days about 1,050,000 gallons were diverted into collection tankers.( The remaining amount was lost in the Gulf). Based on these data (assuming that the rate of loss was ...
*February 6, 2013*

**Math**

The greatest loss rate estimates are 4,200,000 gallons per day since the start of the spill, but after 44 days about 1,050,000 gallons were diverted into collection tankers.( The remaining amount was lost in the Gulf). Based on these data (assuming that the rate of loss was ...
*February 6, 2013*

**Math**

A driver uses about 600 gallons of gas a year to get around his car. For how many years could he drive his car on all the gasoline that is being lost in one day as a result of this spill.. In one day 2,000,000 gallons spilled.
*February 6, 2013*

**Math**

At the time of the oil spill, the price of gasoline was 2.75 per gallon. Estimate how many dollars in gasoline is being lost per day as a result of the spill.-
*February 6, 2013*

**Math**

Trigonometric identity SinD tanD Simplify please
*February 5, 2013*

**Math**

What is the rule for this function? Input: -2, Output: -4 Input: 0, Output: -2 Input: 5, Output: -3 Thank You!! :)
*February 5, 2013*

**Math**

What is the rule for this function? Input: -2, Output: -4 Input: 0, Output: -2 Input: 5, Output: -3 Thank You!! :)
*February 5, 2013*

**Calculus**

Marginal Cost Businesses can buy multiple licenses for data compression software at a total cost of approximately C(x) = 96x2/3 dollars for x licenses. Find the derivative of this cost function at the following values x=8 and x=64 I do not know where to start?
*February 5, 2013*

**Chemistry **

The metal palladium crystallizes in a face-centered cubic lattice with an edge length of 388.8 pm. What is the density of the palladium?
*February 4, 2013*

**Chemistry **

What is the value of q when 8.21g of water vaporizes at 373 K? The enthalpy of condensation of water at 373 K is -40.7 kJ/mol. I tried using the equation q= m x Cs x Delta T, but I never got the right answer which is 18.5 kJ apparently, so I need to find out what I did wrong.
*February 4, 2013*

**Trig **

How do I prove that tan(x/2) =( plus/minus) sqrt(1-cos(x/1+cos(x))
*January 27, 2013*

**BIOLOGY**

What is the majority of the mass of the heart composed of? a. Endocardium b. Myocardium c. Pericardium d. Endothelium
*January 26, 2013*

**physics**

A piece of pipe has an outer radius of 4.6 cm, an inner radius of 2.8 cm, and length of 35 cm. What is the mass of this pipe? Assume its density is 8.3 g/cm3. Answer in units of k
*January 26, 2013*

**physics **

an object weighing 15 newtons is lifted from the ground to a height of 0.22 meter. What is the approximate increase in the object's gravitational potential energy?
*January 23, 2013*

**English **

I need help with my thesis statement for my term paper on Alcatraz. The paper focuses on Alcatraz history, Life on Alcatraz and Famous Prisoners and escapes (10th grade). I have: Alcatraz, a federal penitentiary, history of Alcatraz, life on Alcatraz, while Alcatraz was a ...
*January 22, 2013*

**Calculus**

Use the Mean Value Theorem to find out what c is. f(x)= 2sec^2 x, [-pi/4, pi/4]
*January 22, 2013*

**chemistry, ap chemistry**

At 800 K the equilibrium constant for I2(g) 2 I(g) is Kc = 3.1 10-5. If an equilibrium mixture in a 10.0-L vessel contains 3.56 10-2 g of I(g), how many grams of I2 are in the mixture?
*January 22, 2013*

**Logic**

Situation 1: You have eight billiard balls. One of them is "defective," meaning that it weighs more than the others. How do you tell, using a balance, which ball is defective in two weighings? Situation 2: You have five jars of pills. All the pills in one jar only ...
*January 21, 2013*

**structure and function of the human body**

With your understanding of bone and muscle tissue (cells and the extracellular material) discuss two lifestyle factors (one for bone and one for muscle) that affect the growth, development, size and/or healing (positively or negatively) of the tissue. Also state whether the ...
*January 20, 2013*

**calculus**

limx→∞3x+127x+11
*January 19, 2013*

**Math**

An archer misses the target on her first shot and hits the target on the next 3 shots. What is the least number of consecutive shots that she must now make in order to have hit the target on at least 9/10 of all her shots? ( please show work on how to derive the answer!! Thx...
*January 19, 2013*

**Math**

At a college basketball game, the ratio of the number of freshmen who attended to the number of juniors who attended was 3 to 4. The ratio of the number of juniors who attended to the number of seniors who attended was 7 to 6. What was the ratio of the freshman to the number ...
*January 19, 2013*

**physics**

1 is angle 1 and 2 is angle 2
*January 16, 2013*

**physics **

Consider two vectors where F1 = 53 N, F2 = 81 N, 1 = 320 , and 2 = 13 ,measured from the positive x axis with the counter-clockwise. What is the magnitude of the resulting vector?
*January 16, 2013*

**maths**

A statistician wants to estimate the mean weekly family expenditure on clothes. He believes that the standard deviation of the weekly expenditure is $125. Determine with 99% confidence the number of families that must be sampled to estimate the mean weekly family expenditure ...
*January 16, 2013*

**Math**

Simplify. Express answer with positive exponents -48x^8y^-3/ 12x^-4y^6 Is x^12\4y^9
*January 15, 2013*

**Math**

Expand an simplfy. 3(x-6)(x+4)-(3x-5)^2 Is the answer -6x^2+24x-39
*January 15, 2013*

**Liberal arts math**

if this is the eaquation of a line y=2x+3 what is the parallel line and perpendicular line?
*January 13, 2013*

**english**

write a composition about whirlpools !
*January 11, 2013*

**Social Studies**

Examine The Black Family And Black Religion. Consider How Slavery Affected Both White And Black Views Of Women And Family.
*January 9, 2013*

**Math**

The sum of the integers from 40 to 60, inclusive, is 1050. what is the sum of the integers from 60 to 80 inclusive? Please help me find the pattern and how to use it instead of adding 60+61+62+63..... etc.
*January 9, 2013*

**Math**

The sum of the integers from 40 to 60, inclusive, is 1050. what is the sum of the integers from 60 to 80 inclusive? Please help me find the pattern and how to use it instead of adding 60+61+62+63..... etc.
*January 9, 2013*

**MAth**

what equation is that?
*January 9, 2013*

**MAth**

The front row of a stadium has 25 seats. Each of the other rows has two more seats than the row in front of it. how many seats are there altogether in the first 20 rows? i know how to do this in the "long" way but how do you do this is a "shorter" way by ...
*January 9, 2013*

**calculus**

three forces with magnitudes 100, 50, and 80 lb act on an object at angles of 50 degree, 160 degree, and -20 degree respectively. ind the direction and magnitude o the resultant force.
*January 8, 2013*

**pre-cal**

Three forces with magnitudxes 100, 50 and 80 lbs act on an object at angles of 50 degree, 160 degree and -20 degree respectively.
*January 8, 2013*

**algebra 2**

ok well sorry:P
*December 31, 2012*

**algebra 2**

Oh wait for the axis of symmetry put the vertex form to standard form and then do -b/2a For example: x^2+6x+13 A=1 B=6 C=13 Axis of Symmetry equation x=-b/2a x=-6/2(1) x=-3
*December 31, 2012*

**algebra 2**

vertex(6,-5) Direction is opening down(maximum) I don't know the axis of symmetry...but I hope this helped:)
*December 31, 2012*

**AP Chemistry**

How can you find the average temperature of a refrigerator or any fridge by using colligative properties?? I am doing a lab in school and i'm not sure how to approach or start this. I know that you have to have two solutions where on one solution, you put a tremendous ...
*December 30, 2012*

**chemistry**

sodium carbonate and hydrochloric acid react to give sodium chloride, carbon dioxide and water. How many grams of sodium carbonate and hydrochloric acid would be required to produce 286g of carbon dioxide? step by step answers please:)
*December 29, 2012*

**Calculus-Regressions**

How do you find the best and simplest model given a table of data? I know how to find a specific regression (linear, cubic ect...) but i'm lost when it comes to choosing the best one.
*December 25, 2012*

**Chemistry**

One of the flavouring compounds that have been isolated from aniseed oil is anethole. a.What is the configuration of the molecule, cis or trans? b. The compound will react with bromine. i.What would you observe? ii.Write an equation for the reaction.
*December 19, 2012*

**math**

help please! Factorise (x+4)(3x^2-11x+6)
*December 19, 2012*

**Math**

3.1 ft
*December 16, 2012*

**Precalculus**

log3 (x+1) - log3 (x-3) = 2
*December 11, 2012*

**Precalculus**

ln x -4 In 3 =ln (1/5 x)
*December 11, 2012*

**Precalculus**

More log/exponential equations log2 x + log2(x+2) =3
*December 11, 2012*

**Precalculus**

This is for solving exponential/logarithmic functions: (This is a base e Logarithmic function I would assume): e^(4x)/10 =4^x-2 ? I understand the properties of logs for the most part, but I have a hard time figuring out the step-by-step process on how to solve exponential/log...
*December 11, 2012*

**Math**

What is the simple interest on a loan with a principal of $6,000, an interest rate of 7.39%, and a term of four years?
*December 11, 2012*

**CALCULUS**

a bacteria culture grows with a constant per capita growth rate. After 2 hours there are 500 bacteria and after 6 hours the count is 312500, find the initial population and the population after 8 hours
*December 9, 2012*

**math**

a rectangular prism has l=6" & v= 144in^3. what are possible values for w & h?
*December 7, 2012*

**Grade 11 MAth**

Determine the equation of a sine function that would have a range of {y| -4 ≤ y ≤ 1, y ε R} and a period of 45o. Determine the cosine function that results in the same graph as the function above. Deter
*December 7, 2012*

**Chemistry**

How is the intercept of the Rydberg plot related to the Rydberg constant?
*December 7, 2012*

**Chemistry Check**

I just want to make sure I did the following problem right, and don't have to convert any further. What is the frequency of light whose frequency is 6.4 x 10^15 sec^-1? c= wavelength x v wavelength= c/v 3 x10^8 divided by 6.4 x 10^15 =4.69 x 10^-8?
*December 7, 2012*

**Chemistry**

The ionization energy of hydrogen is 1313 kJ/mol. Covert this energy to: wavelength (nm) 1/wavelength, reciprocal wavelength (cm^-1) spectral region? (IR, visible, UV, etc.) I know E=hv=hc/wavelength h=6.62 x 10^-34 J-s c= 3x10^8 v=c/wavelength But for some reason trying to ...
*December 7, 2012*

**College Chemistry**

Cu(s) + 4HNO3(aq) → Cu(NO3)2(aq) + 2H2O(l) + 2NO2(g) i need the chemical equation and the net ionic equation
*December 6, 2012*

**PHYSICS**

A force of 25.0 N acts at an angle of 25° to the horizontal. Find the horizontal and vertical components of the force.
*December 5, 2012*

**Math**

I have a 73.3 and that is worth 70% of my mark. My final is worth 30%. What do i need to get on my final to finish with anything over a 70%?
*December 5, 2012*

**easy chemistry**

what is the entropy of 10 molecules in a system of 100 boxes?
*December 5, 2012*

**chemistry **

what is the pH of the solution formed when 25 mL of 0.173 M NaOH is added to 35 mL of 0.342 M HCl?
*December 5, 2012*

**chemistry **

a buffer prepared by mixing equal moles of an acid having Ka=4.5x10^-4 and a salt of its conjugate base has a pH of what?
*December 5, 2012*

**chemistry **

the pH of a solution of HIO3 (Ka=1.7x10^-1) and KIO3 is 1.00. what is the molarity of KIO3 if the molarity of HIO3 is 0.025 M?
*December 5, 2012*

**chemistry **

what is the pH of the solution formed when 25 mL of 0.173 M NaOH is added to 35 mL of 0.342 M HCl?
*December 5, 2012*

**chemistry **

a buffer prepared by mixing equal moles of an acid having Ka=4.5x10^-4 and a salt of its conjugate base has a pH of what?
*December 5, 2012*

**chemistry**

the pH of a solution of HIO3 (Ka=1.7x10^-1) and KIO3 is 1.00. what is the molarity of KIO3 if the molarity of HIO3 is 0.025 M?
*December 5, 2012*

**Physics- PLEASE HELP**

The overall length of a piccolo is 30.6 cm. The resonating air column vibrates as in a pipe that is open at both ends. Assume the speed of sound is 343 m/s. (a) Find the frequency of the lowest note a piccolo can play, assuming the speed of sound in air is 343 m/s. (b) Opening...
*December 4, 2012*

**Physics- PLEASE HELP**

The overall length of a piccolo is 30.6 cm. The resonating air column vibrates as in a pipe that is open at both ends. Assume the speed of sound is 343 m/s. (a) Find the frequency of the lowest note a piccolo can play, assuming the speed of sound in air is 343 m/s. (b) Opening...
*December 4, 2012*

**Physics- PLEASE HELP**

The overall length of a piccolo is 30.6 cm. The resonating air column vibrates as in a pipe that is open at both ends. Assume the speed of sound is 343 m/s. (a) Find the frequency of the lowest note a piccolo can play, assuming the speed of sound in air is 343 m/s. (b) Opening...
*December 4, 2012*

**Physics Please Help me!**

The overall length of a piccolo is 30.6 cm. The resonating air column vibrates as in a pipe that is open at both ends. Assume the speed of sound is 343 m/s. (a) Find the frequency of the lowest note a piccolo can play, assuming the speed of sound in air is 343 m/s. (b) Opening...
*December 4, 2012*

**Physics- Elena please help!**

The overall length of a piccolo is 30.6 cm. The resonating air column vibrates as in a pipe that is open at both ends. Assume the speed of sound is 343 m/s. (a) Find the frequency of the lowest note a piccolo can play, assuming the speed of sound in air is 343 m/s. (b) Opening...
*December 4, 2012*

**Algbra**

Marsha must have surgery and she does not have the $2,700 cash necessary for the operation. Talking to an administrator at the hospital, she finds that it will accept MasterCard, VISA, and Discover credit cards. All of these credit cards have an APR of 13%, so she figures that...
*December 4, 2012*

**Algbra**

A car dealer will sell you the $16,650 car of your dreams for $3,290 down and payments of $331.97 per month for 48 months. What is the APR? (Round your answer to the nearest tenth of a percent.) I keep getting the wrong answer. I get 26.1
*December 4, 2012*

**Trigonometry**

Find all solutions between 0 and 2pi to tan(x)=-Squareroot3 exactly.
*December 3, 2012*

**Physics**

Two resistors of equal resistance are connected in series with each other and are connected to a battery that produces a potential difference of 8 V. If the current is 0.2 A what is the value of each resistance?
*December 2, 2012*

**Chemistry**

The compound CH3F has van der Waals constants a = 5.009 atm•L2 /mol 2 and b = 0.0562 L/mol. Using both the ideal gas law and van der Waals’s equation, calculate the pressure expected for 25 mol of CH3F gas in a 5.00-L container at 75 °C. no idea how to even start...
*December 1, 2012*

**Chemistry**

If you place 10.0 L of propanol (C3H8O) in a sealed room that is 7.5 m long, 3 m wide, and 3 m high, will all the propanol evaporate? If some liquid remains, how much will there be? The vapor pressure of propanol is 10.7 torr at 25 °C, and the density of the liquid at this...
*December 1, 2012*

**Chemistry**

Dimethylamine burns in oxygen according to the following equation: 4 C2H7N + 15 O2 → 8 CO2 + 14 H2O + 2 N2 (a) How many liters of O2 at 35 °C and 0.840 atm will be needed to burn 7.70 L of C2H7N at 35 °C and 0.840 atm? (b) How many liters of CO2 at 35 °C and ...
*December 1, 2012*

**Chemistry**

= 728/(2.807)(0.08206)(291.15) =10.855 g ?
*December 1, 2012*

**Chemistry**

What is the molar mass of a compound if a gaseous sample has a density of 2.807 g/L at 18 °C and 728 torr?
*December 1, 2012*

**Physics !:(**

A carbon dioxide laser is an infrared laser. A CO laser with a cavity length of 48.6cm oscillates in the m=100,000.0 mode. What is the wavelength of the laser beam? b). What is the frequency of the laser beam?
*November 30, 2012*

**Calculus**

Find the derivative of y = x^x
*November 28, 2012*

**Calculus**

Find the maximum volume of a cylindrical tin that has a total surface area of 600pi cm^2.
*November 28, 2012*

**Math**

I need help figuring out the unit rate for $5/3. Please help, :D
*November 28, 2012*

**science**

In cattle, red hair and white hair are codominant. Cattle with both white hair and red hair are what? please help! thanks!
*November 27, 2012*

**Physics**

A toy is attached to the cieling by a string. As the toy flies around in a horizontal circle with a radius 45 cm, the string makes an angle of 60 degrees with the cieling. What is the speed of the toy?
*November 27, 2012*

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