Tuesday
May 26, 2015

Posts by Robert


Total # Posts: 881

Physics
A ball rolls off the edge of a balcony at 8.0 m/s. Find its speed after 3.8 s in the air. Use g = 10. m/s2 and enter m/s as unit.
January 22, 2013

Physics
In her physics lab, Jessica rolls a 20-g marble down a ramp and off the table with a horizontal velocity of 1.10 m/s. The marble falls in a cup placed 0.44 m from the table's edge. Find the table's height. Use g = 10. m/s2. Enter m as unit.
January 22, 2013

chinese grammar
§Ú们礼»ª¦a©Ú绝¦oªº­n¨D
January 19, 2013

Science
i belieeve you are working on penn foster :P if you are, you should email me and we can work together on it, im actually almost done with it. my email is rvargas @ live (dot) com. sorry, had to put it that way, cant post email addresses aparently :0
January 14, 2013

Chemistry
An aqueous solution of ethanol is 14.1M C2H5OH. The density of the solution is 0.853g/mL. What is molality of ethanol in the solution? What is mass % of ethanol in solution? I got the molality which is -21.7 ethanol, but I can't figure out how to get the mass % from the ...
January 14, 2013

English
A restrictive clause is one that A. usually occurs at the beginning of a sentence. B. limits the meaning of the word it describes. C. should be set off by commas. D. functions as an adverb.
January 9, 2013

algebra
81x^5 - 3x^2
January 9, 2013

Statistics
Which of the following statements is not true about samples that can be treated as matched pairs data? I. Data collected on these samples is analyzed by calculating the differences between paired observations and using that data in one sample tests. II. Each value in the first...
December 18, 2012

Statistics
The game of chuck-a-luck consists of rolling 3 dice. The player picks a number, 1, 2, 3, 4, 5, or 6. Winning and losing depends on the number of times the number appears on the top of each die. If the number appears once then the winnings are equal to the bet. If the number ...
December 18, 2012

maths
Find the probability of drawing a diamond card in each of the consecutive draws from a well shuffled pack of cards,if the card drawn is not replaced after the first draw
December 14, 2012

math
Thank you ,I think I chose that answer but I did erase at one time and chose 4/5.Find out soon enough ,working on GED and it has been some years.
December 7, 2012

math
1/5
December 7, 2012

math
those were my choices
December 7, 2012

math
If I have 25 balls in a bowl 10 black,5 blue ,5 green ,5 red . what is the probability of me pulling out a red? 1/5 ,4/5,2/10,1/25 etc....
December 7, 2012

Physics
A shear force of 3.1 105 N is applied to an aluminum bar of length L = 19 cm, width w = 5.2 cm, and height h = 2.3 cm as shown in the figure below. What is the shear deformation Äx?____m
December 5, 2012

Steve help pleaseeeee
square root of 5
November 28, 2012

Algebra 2 help please :)
What is a cubic polynomial function in standard form with zeros 1, –2, and 2? Use synthetic division to find P(3) for P(x) = x^4 – 6x^3 – 4x^2 – 6x – 2. Divide 3x^3 + 3x^2 + 2x – 2 by x + 3 using long division. Divide using synthetic division. &#...
November 27, 2012

Algebra 2 help :)
Any number in the form of a+-bi , where a and b are real numbers and b not equal 0 is considered a pure imaginary number. TRUE OR FALSE The minimum value is the smallest y-value of a function. T RUE OR FALSE i2 = square root of -1. TRUE OR FALSE Complex numbers can be graphed ...
November 20, 2012

Algebra 2 help!!!
What value completes the square for the expression? x2 + 14x Use the quadratic formula to solve the equation. x2 – 7x – 6 = 0 Simplify the expression. (–2i)(8i) What are the solutions? 1/2x^2 + 2x + 3 =0 I need help
November 20, 2012

Algebra 2
Can you double check my answer The lengths of the sides of a rectangular window have the ratio 1.6 to 1. The area of the window is 2,560 square inches. What are the dimensions of the window? (1 point) 50.6 inches by 50.6 inches 40 inches by 64 inches 40 inches by 80 inches <...
November 18, 2012

HELP ! Algebra
Solve the quadratic equation by completing the square. (-x^2 + 6x + 10 = 0)
November 16, 2012

HELP !!! Algebra 2
15. What is the solution of the linear-quadratic system of equations? {y = x^2 + 5x - 3} {y - x = 2}
November 16, 2012

Statistics
@John I have come from a year later to reply to your concern, to uproot this tyranny that is Math Guru. No longer shall we sit wondering what the other half of the question is. No longer must we be given a formula and have to solve it out. NO LONGER MUST WE SIT THROUGH THIS. ...
November 5, 2012

Statistics
I got only love for John. The answer is fate
November 5, 2012

physics
Since the masses stick together, there is conservation of momentum but no conservation of energy. Let x be the new velocity. Hence, 0.5*0.4 + 0.8*(-0.20) = (0.5+0.8)*x X = (0.2-0.16)/1.3 = 0.0307 m/s KE = 0.5*1.3*0.0307^2 = 0.000615 J.
October 30, 2012

Science
While traveling along a highway a driver slows from 24 m/s to 15 m/s in 12 seconds. What is the automobile's acceleration? How would I show the work and find this answer?
October 29, 2012

Algebra 2
3. Identify the vertex and the axis of symmetry of the graph of the function y = 3(x + 2)2 – 3. (1 point) A- vertex: (2, –3); axis of symmetry: x = 2 B- vertex: (–2, –3); axis of symmetry: x = –2 C- vertex: (2, 3); axis of symmetry: x = 2 D- vertex...
October 25, 2012

chemistry
how many milliliters of 0.250 M KMnO4 are needed to react with 3.55 grams of iron(II)sulfate, FeSO4? the reaction is as follows: 10FeSO4(aq)+2KMnO4(aq)+8H2SO4(aq)¨ 5Fe2(SO4)3(aq)+2MnSO4(aq)+K2SO4(aq)+8H2O(l)
October 23, 2012

chemistry
WHAT IS THE VOLUME IN MILLILITERS OF 0.100 SULFURIC ACID CONTAINING 0.949 GRAMS H2SO4
October 23, 2012

Algebra 2 Helpp :(
QUESTIONS (vvv) (1) Solve the system by subsitution 2x + y = -11 3 - 4y = 11 (2) Solve the system by elimination 2x + 6 = -12 5x - 5y = 10 (3) What is the solution of the following system? -3x - 2y = -12 9x + 6y = -9 (4) What is the solution of the following system? x - y = 11...
October 23, 2012

Algebra 2 Please Help
22. The graph of g(x) is f(x) translated to the left 8 units and up 2 units. What is the function rule for g(x) given f(x) = x²? (2 points)
October 22, 2012

Algebra 2 Please Help
Please show your work on how you got the answer please and thank you :)
October 22, 2012

Algebra 2 Please Help
21. A candle is 17 in. tall after burning for 3 hours. After 5 hours, it is 15 in. tall. Write a linear equation to model the relationship between height h of the candle and time t. Predict how tall the candle will be after burning 8 hours. (2 points)
October 22, 2012

Ratios of Similar Figures
is number 5 c?
October 22, 2012

nutrition
Jonathan, a two-and-a-half-year-old, lives with his mother and brothers at his grandmother's house in Chicago. His mother, Anita, works at a pharmacy to support the family. Jonathan spends his days at home with his grandmother. While Anita works, his grandmother brings the...
October 18, 2012

History
ccbdb
October 17, 2012

Microeconomics - University of Boston
4. If Cassandra bought 16 cotton blouses last year when her income was $40,000 and she buys 24 cotton blouses this year when her income is $50,000, then what is her income elasticity of demand? Interpret what the income elasticity of demand you just calculated means to you. ...
October 17, 2012

Microeconomics
4a. In the market for hand-made guitars, when the price of guitars is $800, annual revenues are $640,000. When the price falls to $700, annual revenues decline to $630,000. Over this range of guitar prices, is the demand for hand-made guitars elastic, unit-elastic, or ...
October 17, 2012

Microeconomics
The producer of X is contemplating a price change and has asked for your advice. After some empirical investigation, you conclude that the price elasticity of demand for X is 1.25. As an economist, what would you advise the producer to do in order to raise total revenue? Would...
October 17, 2012

Physics
In Case A the mass of each block is 4.8 kg. In Case B the mass of block 1 (the block behind) is 9.6 kg, and the mass of block 2 is 4.8 kg. No frictional force acts on block 1 in either Case A or Case B. However, a kinetic frictional force of 9.4 N does act on block 2 in both ...
October 14, 2012

chemistry
in an experiment, 2.50g of salicylic acid is reacted with 10.31g of methanol. the yield of methyl salicylate, C8H8O3, is 1.27g. what is the percentage yield?
October 13, 2012

chemistry
if a reaction vessel contains 11.5g NH3, 12.0g O2, and 10.5g CH4, what is the maximum mass in grams of hydrogen cyanide that could be made?
October 13, 2012

chemistry
in a reaction of 3Cu(s)+ 8HNO3(aq)¨ 3Cu(NO3)2(aq) +2NO(g) + 4H2O(l). if 5.58 grams of Cu(no3)2 is made how many grams of nitrogen monoxide is present
October 12, 2012

chemistry
copper metal reacts with nitric acid. assume that the reaction is 3Cu(s) + 8HNO3(aq) ——> 3Cu(NO3)2(aq) + 2NO(g) + 4H2O(l). if 5.58 grams of Cu(NO3)2 is obtained, how many grams of nitrogen monoxide would have formed
October 12, 2012

Science
In the early 20th century, some scientists were reluctant to accept the conclusion that DNA could be the genetic material because it is so_________________.
October 9, 2012

IMPERIALISM AND THE PROGRESSIVE ERA
Ivy L. Lee
October 9, 2012

Biology
A bacterium that synthesizes an enzyme that neutralizes an environment toxin would probably use a(n) _____________ operon to regulate production of the enzyme.
October 9, 2012

world history
you should email me, im also in Penn Foster lol we could cut work in half if we work on this crap together.. rvargas1020 @ live . com
October 6, 2012

english 4
Please explain to me how to determine the answer im looking for
October 3, 2012

english 4
if i knew i would not ask
October 3, 2012

english 4
The two waiters exchanged a look whose meaning was clear to me. what type of clause or phase is used?
October 3, 2012

english4
can you explain to me how to determine what type of verbal it is my choices are Participle, Gerund, and infinitive
October 3, 2012

english4
What do you think Ms. Sue
October 3, 2012

english4
Well as the verbal i chose "to be moved" im not sure what type of verbal it is!
October 3, 2012

english4
He will not allow the table to be moved. identify the Verbal in the sentence and type of verbal
October 3, 2012

english4
what type of clause or phrase is used in the sentence: we hit a snag while rowing to shore
October 3, 2012

math
Average Growth Rate(2000-2009)of China - GDP: 10.9 Population: 0.8 Per Capita GDP: 10.1 Ethiopia - GDP: 7.5 Population: 2.8 Per Capita GDP: 4.7 How fast does total output(GDP)have to grow in order to raise per capita GDP in Instructions: Enter your responses to one decimal ...
October 3, 2012

English
What are the nouns and verbs in the sentence. Life is full of choices, so I must learn to make good ones.
September 27, 2012

Biochemistry
Acetylcholinesterase catalyzes the hydrolysis of the neurotransmitter acetylcholine: Acetylcholine + H2O  actetate + choline The KM of acetylcholinesterase for its substrate acetylcholine is 9 x 10-5 M. In a reaction mixture containing 5 nanomoles/ml of ...
September 22, 2012

Linear Algebra
awesome, thanks a lot Steve, that link will come in handy!
September 21, 2012

Linear Algebra
Solve the following system using Gauss's algorithm (a) x1 + 2x2 + 4x3 + 6x4 = 3 2x1 + x2 + 3x3 = -6 -2x1 + x2 + 6x3 + 4x4 = -11 2x1 + x2 + x3 = 0 so the matrix will be: 1 2 4 6 3 2 1 3 0 -6 -2 1 6 4 -11 2 1 1 0 0
September 21, 2012

Math
Staring from the pit, Helen made three laps around a circular track at 40 seconds per lap. She than made a 30-second pit stop and two and a half laps before running off the track and getting stuck in the mud for the remainder of the race. Graph Helen's distance from the ...
September 18, 2012

Calculus
Calculate the following integral and determine whether it's convergent, or divergent. integral at [-3,0] x dx / sqr(9 - x^2)
September 15, 2012

calculus
Thanks Reiny and Steve. Now to pass the exam!
September 14, 2012

calculus
Calculate the following integral: ∫ dx / x(1 - √x)^2
September 14, 2012

Calculus
thanks Steve! You're a lifesaver
September 13, 2012

Calculus
Calculate the following integral: ∫ sec^4 (3x)/ tan^3 (3x) dx For this one, can I bring up the tan to tan^-3?
September 13, 2012

Algebra
Algebra Question: A team wins 15 of their first 20 games. If they win only half the time from now on, how many games will they have to play in order to win 60% of their total games? I have it figured out manually, but cant get it in equation form.
September 12, 2012

Calculus - Question
If I go with my first assumption I get this: ∫ sec^4 (3x) tan^-3 (3x) = ∫ sec^3 (3x) tan^-4 (3x) sec(3x)tan(3x) dx = ∫ sec^3 (3x) (sec^-4 3x - 1)sec(3x)tan(3x) dx u = sec(3x) dx du = 3sec(3x)tan(3x) dx > 1/3du = 1/3 ∫ u^3 (u^-4 - 1) du = 1/3 ∫...
September 12, 2012

Calculus - Question
Or do I use the rule of ∫ sec^n x dx divided by the rule of ∫ tan^n x dx?
September 12, 2012

Calculus - Question
Am I allowed to do this? for the integral of ∫ sec^4 (3x)/ tan^3 (3x) dx I change it to ∫ sec^4 (3x) tan^-3 (3x) From here I use the rule for trigonometry functions.
September 12, 2012

Linear Algebra
Last number from the sample test! A plane P passes by the coordinates: A(1,0,-7); B(-2,-1,0); C(0,0,-3) Using the equation of the line D: x= 7+12t, y= -1-6t, z= 2-2t, Find the equation of a line that's entirely part of the plane P and that is perpendicular to the line D at...
September 10, 2012

Linear Algebra 2
This is another question I can't figure out. Given planes pie1 and pie2 defined as: pie1: 2x + 5y - 7x + 2 = 0 pie2: x + y - z + 3 = 0 (b) Give the equation of the line of intersection of these two planes. I only found the answer for (a) where they ask to find the angle ...
September 9, 2012

Linear Algebra
THanks again Mate! You've been a big help lately, I really appreciate it.
September 9, 2012

Linear Algebra
So I'm studying for my first exam and I'm stuck on this number. Given both lines: D1: (x,y,z) = (2,0,0) + k(0,3,0) D2: (x,y,z) = (2,0,2) + k(0,0,1) (a) Give the algebraic equation of the plane containing both lines. I know that I have to start off by finding the ...
September 9, 2012

Linear Algebra
THanks Mate!
September 8, 2012

Linear Algebra
2 people move in the same direction along a line of equation: (x + 3)/10 = (y + 10)/20 = (z - 10)/-20 Mobile M1 is at a point A(-3, -10, 10) and moves at a velocity of 6m/s towards point B(7, 10, -10) where Mobile 2 is found, walking in the same direction at a velocity of 3m/s...
September 8, 2012

Calculus
THanks Steve and Reiny!
September 7, 2012

Calculus
Hello, I just wanted to verify if my work was good. Calculate the following integral by parts: ∫ upper limit is 1/5 and lower limit is 1/10. of 10sin^-1 (5x)dx so first I named the variables: u = 10 sin^-1 (5x) du = 50 / sqr(1-25x^2) dv = dx v = x so we get: = 10 sin^-1...
September 7, 2012

Definite integral by parts (correction)
Hello, I just wanted to verify if my work was good. Calculate the following integral by parts: ∫ upper limit is 1/5 and lower limit is 1/10. of 10sin^-1 (5x)dx so first I named the variables: u = 10 sin^-1 (5x) du = 50 / sqr(1-25x^2) dv = dx v = x so we get: = 10 sin^-1...
September 5, 2012

Math
Knowing u = (4,0,-3), v = (x,3,2) and that the orthogonal projection of v on u is a vector of norm 6, determine x. Thank you
August 27, 2012

Linear Algebra
Ok this is the last one I promise! It's from a sample exam and I'm practicing for my finals :) Verify if the following 4 points are consecutive vertices of a parallelogram: A(1,-1,1); B(3,0,2);C(2,3,4);D(0,2,3) (b) Find an orthogonal vector to the plane containing the ...
August 27, 2012

Linear Algebra 2 question
sorry I wrote D, but there is no D, just AB and C
August 26, 2012

Linear Algebra 2 question
Hello, I have another question from my linear algebra class. I'm asked to find the area of a triangle using determinants, but they don't give me the vertices, only the sides. Where A,B,C and D are the vertices, u and v are 2 out of the 3 sides. Now they give me u=(-3,1...
August 26, 2012

Linear Algebra
Knowing u = (4,0,-3), v = (x,3,2) and that the orthogonal projection of v on u is a vector of norm 6, determine x. Thank you
August 26, 2012

science
1.How many meters away is a cliff if heard one half second after the original sound? Assume that sound travels at 343m/s on that day
August 21, 2012

Physics - Electromagnetism 2
Two coils, held in fixed positions, have a mutual inductance of 165 µH. What is the peak emf in one coil when the current in the other coil is I(t) = 16.0 sin(1.15 103t), where I is in amperes and t is in seconds? Just a few hints on how to start it off would be very ...
August 16, 2012

Physics - Electromagnetism
An inductor in the form of a solenoid contains 440 turns and is 15.8 cm in length. A uniform rate of decrease of current through the inductor of 0.421 A/s induces an emf of 175 µV. What is the radius of the solenoid?
August 16, 2012

Physics 2
thanks. It's all good, I understand your approach and I really appreciate it!
August 14, 2012

Physics 2
thank you very much drwls, this is a question from a sample exam, getting ready for my finals tomorrow!
August 14, 2012

Physics 2
the character that doesn't show up is the emf (E)
August 14, 2012

Physics 2
Show that during the charging of the capacitor in an RC circuit, the charge of the capacitor, as a function of time, is: q(t) = C(1 – e-t/RC)
August 14, 2012

Physics - Electromagnetism
A charge +q is at the origin. A charge –2q is at x = 2.00 m on the x axis. For what finite value(s) of x is (a) the electric field zero? (b) the electric potential zero?
August 14, 2012

enviroment
The surroundings or conditions in which a person, animal, or plant lives or operates.
August 13, 2012

Physics - Electromagnetism
A square loop (length along one side = 20 cm) rotates in a constant magnetic field which has a magnitude of 2.0 T. At an instant when the angle between the field and the normal to the plane of the loop is equal to 20 and increasing at the rate of 10/s, what is ...
August 12, 2012

Physics - Verification
Two long straight parallel wires separated by a distance of 20 cm carry currents of 30 A and 40 A in opposite directions. What is the magnitude of the resulting magnetic field at a point that is 15 cm from the wire carrying the 30-A current and 25 cm from the other wire? So I ...
August 12, 2012

Life Science
10 Microsporidia Chytridiomycota Neocallimastigomycota Blastocladiomycota Zoopagomycotina Kickxellomycotina Entomophthoromycotina Mucoromycotina Glomeromycota Dikarya
August 12, 2012

math
61-43 (Goal % and current %) = 18 % 18% / 0.6% = 30 years
August 12, 2012

Art Appreciation
Discuss how art was used as a vehicle for propaganda, and whether such use is present in the works of Höch, Grosz, and Picasso. Use one example from Gardner's Art through the Ages and one from the Internet.
August 9, 2012

Calculus - Riemann Sum
Given a function f(x) = squr(3 + 2x), on [-1,1], subdivided into 4 equally large intervals, calculate the Riemann sum SR4 = 4Ei=1 f(xi)delta(x). my attempt at the solution: [-1,1], a = -1 and b = 1 delta(x) = 1 - (-1)/n = 2/n xi = a + delta(x)i xi = -1 + 2/n(i) so after adding...
August 6, 2012

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