Most popular questions and responses by q
  1. Physics

    A refrigerator has a coefficient of performance of 4.0. When removing 2.4x10^4 J from inside the refrigerator, how much energy is sent into the environment?

    asked on November 19, 2012
  2. Grade 12 Calculus

    A rectangular piece of paper with perimeter 100 cm is to be rolled to form a cylindrical tube. Find the dimensions of the paper that will produce a tube with maximum volume. I have made it up to getting an equation for V(w).

    asked on March 25, 2014
  3. Grade 12 Calculus

    For an outdoor concert, a ticket price of $30 typically attracts 5000 people. For each $1 increase in the ticket price, 100 fewer people will attend. The revenue, R, is the product of the number of people attending and the price per ticket. a) Let x

    asked on March 25, 2014
  4. Calculus

    There are 50 apple trees in an orchard, and each tree produces an average of 200 apples each year. For each additional tree planted within the orchard, the average number of apples produced drops by 5. What is the optimal number of trees to plant in the

    asked on March 25, 2014
  5. English.

    Please check my answers? Letter of Recommendation Mary O'Dell PLTW Program Willow High School 1400 Old Tamah Road Irmo, SC 29067 April 11, 2007 Subject: Letter of Recommendation for Mr. Chris Moses To Whom It May Concern: Chris studied under my supervision

    asked on March 12, 2015
  6. physics

    In attempting to jump up a waterfall, a salmon leaves the water 2.0 m from the base of the waterfall. With what minimum speed must it leave the water in order just to make it up a waterfall 1.6 m high?

    asked on September 22, 2013
  7. AP Chemistry

    The Ksp of Ni(CN)2 is 3.0 × 10−23. What is the molar solubility of Ni(CN)2 in a 0.065 M KCN solution? Answer in units of mol/L. I found that the normal molar solubility is 1.957x10^-8, but I don't know how the KCN solution affects it. Sig figs aren't

    asked on January 20, 2015
  8. Math

    water flows over a dam at a rate of 500 gallons per minute write a function rule relating the amount of water a that flow over the dam to the number of minutes m that have passed what are the initial value and rate of change

    asked on February 8, 2016
  9. chemistry

    How would you do this question: A student dissolved 5.0 g of vitamin C in 250 mL of water. The molar mass of ascorbic acid is 176 g/mol, and its Ka is 8.0 × 10−5. Calculate the pH of the solution. Note: Abbreviate the formula of ascorbic acid to HAsc.

    asked on June 7, 2014
  10. Math 3rd

    Tim tracked the change in outside temperature one afternoon. He recorded a temp of 85.4 f at noon. The Temperature then rose 3.85 f over the next 4 hours. At 5:00 Tim recorded the temperature of 89.25 f how did the temperature change betwn 4:00pm and

    asked on March 13, 2017
  11. MATH157


    asked on March 18, 2010
  12. math

    simplify (8*10^7)(7*10^4) i think it's 5.6*10^10 simplify (3*10^6)(8*10^-4) i think it's 2.4*10^3 Astronomers measure large distances in light-years. One light-year 5.88*10^12 mi Star is 9.8*10^1 light years from Earth in scientific notation how many miles

    asked on March 10, 2017
  13. science

    Egg-laying land animals have evolved to produce eggs with tough shells to ensure that A .external fertilization can take place. B.the egg and sperm can fuse C.parental care is unnecessary*** D. the developing embryo does no dry out

    asked on February 19, 2019
  14. chemistry

    i need help solving this Benzoic acid is a weak, monoprotic acid (Ka = 6.3 × 10−5). Calculate the pH and the percent dissociation of each of the following solutions of benzoic acid. Then use Le Châtelier’s principle to explain the trend in percent

    asked on June 7, 2014
  15. AP Chemistry

    Calculate ΔHrxn for the following reaction: C(s)+H2O(g)→CO(g)+H2(g) Use the following reactions and given ΔH values: C(s)+O2(g)→CO2(g), ΔH= -393.5 kJ 2CO(g)+O2(g)→2CO2(g), ΔH= -566.0 kJ 2H2(g)+O2(g)→2H2O(g), ΔH= -483.6 kJ

    asked on December 7, 2015
  16. Physic

    A space station that does not rotate cannot simulate gravity for its occupants. A)True B)False From within a rotating reference frame, the centrifugal force simulates gravity. A)True B)False On a rotating station, a person at the center of the station, in

    asked on November 30, 2018
  17. chemistry

    Determine the number of representative particles in each of the following and identify the representative particle. a. 13.0 mol Ag b. 23.7 mol H20 c. 0.178 mol NaCl

    asked on January 13, 2010
  18. chemistry

    how many grams of CaCl2 would be dissolved in 1.9 liters of a 0.2 molarity solution of CaCl2?

    asked on January 13, 2010
  19. algebra

    If Jenny's car uses less gas per mile driven than Sandra's truck, how does the graph representing the rate of change of Sandra's truck compare to the graph representing the rate of change of Jenny's car?

    asked on June 16, 2013
  20. chemistry

    Determine the number of moles of sulfate ions present in 1.20 mol iron(III) sulfate (Fe2(SO4)3).

    asked on January 13, 2010
  21. life science

    Explanation of why the process of mitosis and meiosis are both important to a living organism. When would an organism need to undergo the process of mitosis? When would an organism need to undergo the process of meiosis? What would happen if meiosis did

    asked on August 10, 2007
  22. Chemistry

    Consider this equilibrium N2(g) + H2(g) NH3(g) +94 kJ The equilibrium law exoression for the balanced chemical equationwould be A. [N2][H2]/[NH3] B. [NH3]/[H2][N2] C. [NH3]2/[H2][N2] D. [NH3]2/[H2]3[N2] E. 2[NH3]2/3[H2]3[N2]

    asked on January 3, 2012
  23. chemistry

    Calculate the amount of heat absorbed when 58 g of steam at 117◦C are completely converted to ice at −32.5◦C. Specific Heat: H2O(s) = 2.09 J/g◦C H2O(l) = 4.18 J/g◦C H2O(g) = 2.03 J/g◦C Heat of Fusion = 334 J/g Heat of Vaporization = 2260 J/g

    asked on November 15, 2014
  24. Calculus

    Find a positive number such that the sum of the square of the number and its reciprocal is a minimum.

    asked on March 25, 2014
  25. Calculus

    Evaluate the surface integral. the double integral of (x^2 + y^2 + z^2)dS over Region S. S is the part of the cylinder that lies between the planes z = 0 and z = 5, together with its top and bottom disks Can anyone help?

    asked on November 6, 2013
  26. english

    What is the author referring to in this reading passage? Thus early had that one guest,--the only guest who is certain, at one time or another, to find his way into every human dwelling, --thus early had _______ stepped across the threshold of the House of

    asked on July 7, 2013
  27. chemistry

    A jogger runs at an average speed of 5.9 mi/h. If she starts a run at 11:15 am, what time is it after she covers 4.75 x 104ft?

    asked on September 3, 2010
  28. Calculus

    Linda has $9000 to invest. She invested x dollars in an account that earned 3% simple interest and the remainder of the money in an account that earned 2.6% simple interest. In one year, both accounts together earned $250 interest. How much was invested in

    asked on February 5, 2015
  29. chemistry

    A sample of silver chromate (Ag2CrO4) has a mass of 29.0 g. (a) How many Ag+ ions are present? (b)What is the mass in grams of one formula unit of silver chromate? (c) How many CrO42- ions are present?

    asked on January 13, 2010
  30. physics

    A 47.0 g golf ball is driven from the tee with an initial speed of 54.0 m/s and rises to a height of 23.2 m. (a) Neglect air resistance and determine the kinetic energy of the ball at its highest point. What is its speed when it is 9.0 m below its highest

    asked on October 21, 2008
  31. help with solving

    x^2+(x-2)^2 = (2x-6)^2 solve for x. thanks so much. Please keep in mind that tutors here won't simply do your work for you. I'm sure you'll get a better response if you show your work as far as you can get, so tutors will know where you get stuck. =) it

    asked on August 3, 2007
  32. math

    a football player attempts a field goal from a distance of 52 yards. The ball reaches a maxium height of 9 yrds and lands 8 yards behind the uprights. If the uprights are 3 yards high. algebraically determine if the field goal was successful

    asked on November 6, 2014
  33. Physics

    A refrigerator does 18kJ of work while moving 115 kJ of thermal enegy from inside the refrigerator. What is its coefficient of performance?

    asked on November 22, 2012
  34. Science

    I need to know how to compare mouthwash and toothpaste...what to compare?.. compare bacteria samples in salaiva.

    asked on February 26, 2007
  35. PHYS

    You throw a bowling ball o the empire state building(381m high) 10m/s down- ward. How long does it take to get to the bottom?

    asked on June 17, 2013
  36. engineering mechanics

    A person A is trying to keep his balance while on a sled B that is sliding down an icy incline. Let mA = 78kg and mB = 25 kg be the masses of A and B, respectively. In addition, let the static and kinetic friction coefficients between A and B be μs = 0.4

    asked on December 31, 2012
  37. maths

    if 3x + 8 =20 - 3x, what is x

    asked on August 27, 2011
  38. geometry

    if 3x + 8 =20 - 3x, what is x

    asked on August 27, 2011
  39. math

    5x-3y=11 4x-7y=18

    asked on December 2, 2010
  40. algebra

    i need help finding the base. this is the equation i got after work it out halfway. 42/h+h+sqroot(42/h)^2+h^2=20 ft how can i find B & H. How should i go about. Thanks. Isnt the sqrt of (42/h)^2 just 42/h ? Then, multipy both sides of the equation by h,

    asked on August 6, 2007
  41. algebra

    solve for x (24+2x)(10+2x) - 240 = 152 First multiply. 24(10) = ___ 2x (2x) = ____ Now subtract 240. Can you finish the problem from here? dont i need to put this in equatic equation to solve for x. cause i need to find the width of a small rectangle

    asked on August 3, 2007
  42. Algebra

    110 student went to the lake for a boat ride. there were 8 both (each would safely hold the same number of student), and all but 14 students could go for a ride. those remaining 14 students had to wait until first students finished their ride before they

    asked on September 21, 2016
  43. Algebra II

    From 1990-1994 the mail order sales of health products can be modeled by S= 10t^3+115t^2+25t+2505 where S is the sales (in millions) and t the number of years since 1990. In what year were about $3885 million health products sold.

    asked on March 2, 2015
  44. Math

    2x√3x*2√x i was wondering how to simplify this

    asked on February 17, 2014
  45. Complex Math

    Compute all possible values of e^i

    asked on November 25, 2013
  46. physical

    David's clock ticks once for every two of Phil's clock ticks. How fast is Phil moving by David?

    asked on June 17, 2013
  47. physical

    Franky claims he has a mass of 65kg. He is sitting on a spherical bouy that oats just barely submerged under water. When he gets o it rises halfway out of the water. What must the radius R in centimeters of the sphere be for him to be telling the truth?

    asked on June 17, 2013
  48. Quick Math Question

    How do I add time? If a person worked 4 1/2 hours on Monday, 4 1/2 hours on Tuesday and 2 hours on Wednesday, does that add up to 12 hours? If not, how much more time would the person need to work the next day to equal 12 hours?

    asked on March 28, 2013
  49. american government

    What is the difference between civil liberties and natural rights?

    asked on May 4, 2011
  50. Math

    2x(√3x^2)*2√x how would you simplify this?

    asked on February 17, 2014
  51. multivariable calculus

    Studying for a test, and saw this: Find the center of mass of the hemisphere x^2 + y^2 + z^2 = a^2; z>=0 if it has constant density. Any ideas?

    asked on November 6, 2013
  52. Math

    For a class C corporation in Louisiana, the amount of state income tax S is deductible on the federal return and the amount of federal income tax F is deductible on the state return. With $200,000 taxable income and a 30% federal tax rate, the federal tax

    asked on October 17, 2012
  53. Chemistry

    which of the following statement are true for all electric cells? I. electrons flow from the anode to the cathode II. reduction occurs at the anode III. oxidation occurs at the cathode IV. oxidation occurs at the anode V. reduction occurs at the cathode A.

    asked on January 3, 2012
  54. accounting

    Derm Travel Agency accepted a four-month, 9% interest rate, 52.000 note from one otits customers on May 1, 2008. The entire balance is payable at the notes maturity. Prepare the May 31 adjusting journal entry related to this note. Do I debit cash and

    asked on November 13, 2010
  55. Chemistry

    why different detergents have different price?on what physical properties are their qualities based?

    asked on January 19, 2010
  56. math

    The sales representative informs you that there are two floor plans available, and that there are a total of 56 houses available. Use x to represent floor plan #1 and y to represent floor plan #2. Write an equation that illustrates the situation. The sales

    asked on April 25, 2009
  57. Life Science

    How did Mendel’s approach to answering scientific questions differ from that of his contemporaries? Thank you for using the Jiskha Homework Help Forum. You might want to see the answer just posted for Diana.

    asked on August 4, 2007
  58. Life science

    are humans subject to the same pressure of natural selction as other organism Humans show signs of natural selection occuring, according to these studies. http://www.news.cornell.edu/stories/Oct05/Bustamante.kr.html (Broken Link Removed)

    asked on July 25, 2007
  1. calculus

    iii. answer is 48.094

    posted on January 30, 2019
  2. Social Studies

    14. A "(in the former Soviet Union) the policy or practice of more **open** consultative government and wider dissemination of information, initiated by leader Mikhail Gorbachev from 1985." 15. B "(in the former Soviet Union) the policy or practice of

    posted on January 24, 2019
  3. Edtech


    posted on December 13, 2018
  4. Science

    -)_(- is correct tysm

    posted on October 23, 2018
  5. Astronomy


    posted on September 27, 2018
  6. Science

    Bruh is correct! Thanks!! Answers: 1. A 2. D 3. B 4. B 5. A

    posted on September 26, 2018
  7. Social Studies


    posted on September 21, 2018
  8. English Check my answers please


    posted on September 18, 2018
  9. Math


    posted on February 28, 2018
  10. statistics


    posted on February 22, 2018
  11. Chemistry

    The phase fraction is calculated using the 'Lever Rule'. I can't figure out how to do it, but it involves using this formula- X = (c-b)/(a-b) Where a, b, and c are distances between x-coordinates at various phase boundaries. But the phase diagram in this

    posted on December 3, 2017
  12. Chemistry


    posted on December 1, 2017

    no its wrong

    posted on September 11, 2017
  14. chemistry


    posted on March 23, 2017
  15. Chemistry

    The answer is 36

    posted on March 21, 2017
  16. SCGC


    posted on January 23, 2017
  17. 8th grade


    posted on December 6, 2016
  18. Improving writing assignment

    I have noticed that in the last three months, the performance and qualities of work has been compact due to workloads unbalanced, since Jessica Hilo our executive manager has been on medical leave for last four months. Her responsibilities have been shared

    posted on June 3, 2016
  19. math


    posted on December 7, 2015
  20. social studies

    what colonies French find as a result of the northwest passage way.

    posted on November 17, 2015
  21. Soc Stud

    so its c

    posted on October 21, 2015
  22. Maths Probability

    Anyone got right answer for c = ?

    posted on May 25, 2015
  23. Probability

    Is that the right answer for c?

    posted on May 25, 2015
  24. probability

    Let N be the numbers of passengers that show up. So p=0.9 and E[N]=0.9n and σ=(n*0.1*0.9)^1/2=0.3*n^1/2. Using Moivre-Laplace we have P(N≥300.5)≈0.01 Next you should use CLT, solving quadratic equation and find value of n

    posted on April 29, 2015
  25. Probability

    Jacob, can you explain how did you get these answers? I want understand this problem

    posted on April 15, 2015
  26. English.


    posted on March 12, 2015
  27. AP Chemistry

    I got it! The initial concentration of CN- would be 0.065 M rather than 0 M.

    posted on January 20, 2015
  28. AP Chemistry

    The Ksp of Ni(CN)2 is 3.0 × 10−23. What is the molar solubility of Ni(CN)2 in a 0.065 M KCN solution? Answer in units of mol/L. I found that the normal molar solubility is 1.957x10^-8, but I don't know how the KCN solution affects it. Sig figs aren't

    posted on January 20, 2015
  29. physics

    shut up

    posted on December 8, 2014


    posted on November 5, 2014
  31. Grade 12 Calculus


    posted on March 25, 2014
  32. math

    You receive an invoice for $565.00 with terms 3/10, net 30. If you pay it immediately, how much will you pay?

    posted on November 20, 2013
  33. chemistry

    Answer is 1480g Do the math. Someone already gave the formula. The cm cancels out after multiplying. Note: you have to cube the 5.5cm

    posted on September 1, 2013
  34. math


    posted on May 9, 2013
  35. Quick Math Question

    okay thx

    posted on March 28, 2013
  36. Auditing


    posted on April 4, 2012
  37. social studies

    Without our two great political parties cutting across economic and geographic interests, democracy as we know it could never have been made to function." The author of this statement probably meant to suggest that

    posted on June 13, 2011
  38. spelling

    well what is it? i don't get it :'(

    posted on May 5, 2011
  39. Math

    a.Set table as x,chair as y 90x+40y

    posted on March 20, 2011
  40. chinese

    tian cai

    posted on March 20, 2011
  41. math

    6 minutes

    posted on March 7, 2011