# brian

Most popular questions and responses by brian-
## Physics

A 0.075 kg ball in a kinetic sculpture moves at a constant speed along a motorized conveyor belt. The ball rises 1.32 m above the ground. A constant frictional force of 0.350 N acts in the direction opposite the conveyor belt's motion. What is the net work

*asked on December 9, 2010* -
## math Question

Find an equation that models a hyperbolic lens with a=12 inches and foci that are 30 inches apart. assume that the center of the hyperbola is the origin and the transverse axis is vertical.

*asked on May 19, 2014* -
## Calculus I, differentiation

The number, N, of people who have heard a rumor spread by mass media by time, t, is given by N(t)=a(1−e−kt). There are 6 million people in the population, who hear the rumor eventually. If 5% of them heard it on the first day, find the percentage of

*asked on February 24, 2013* -
## math/statistics

In the Numbers Game, a state lottery, four numbers are drawn with replacement from an urn containing balls numbered 0-9, inclusive. Find the probability that a ticket holder has the indicated winning ticket. The first three digits in exact order.

*asked on June 19, 2017* -
## Math

Postal regulations specify that a parcel sent by priority mail may have a combined length and girth of no more than 96 in. Find the dimensions of a rectangular package that has a square cross section and the largest volume that may be sent via priority

*asked on April 4, 2012* -
## Chem

what kind of intermolec forces are in NH4Cl i thought it was london dispersion, dipole dipole, and hydrogen bonding and nottttt ionic. what am i doing wrong?

*asked on November 24, 2008* -
## English

Dragonwings by Laurence yep What conflict is left unresolved at the end?

*asked on June 7, 2015* -
## AP CHEM

Complete and balance the reaction Al(s) + Pb2+(aq) ! using the smallest possible integers. I got: 2Al(s) + 3Pb2 ==> Al2Pb3 Calculate the standard free energy. Faraday’s constant is 96485 J V · mol Answer in units of kJ/mol. I know the formula is -nFE

*asked on October 21, 2010* -
## Math

One model of Earth's population growth is , where t is measured in years since 1990, and P is measured in billions of people. Which of the following statements are true?

*asked on August 6, 2014* -
## math

when might you think you're built upside down?

*asked on September 24, 2008* -
## Chemistry

Given that ΔH (fusion) of water is 6025 J/mol, Cp,m(ice) = 37.7 J K–1 mol–1, and Cp,m(water,liquid) = 75.3 J K–1 mol–1, calculate ΔG (in J) for the freezing of 89 moles of water at 1 atm pressure and the constant temperature T = 14.4 °C. I got

*asked on January 28, 2016* -
## CHEMISTRY

Calculate ΔSfus and ΔSvap for HF. Determine the entropy change when 7.60 mol of HF(l) freezes at atmospheric pressure. I already calculated ΔSfus as 24.103 J/k*mol and ΔSvap as 86.07 J/K*mol....These are correct (I checked them already). I need help

*asked on March 14, 2012* -
## Chemistry

Explain how a person bailing out a row boat with a leak could represent a state of physical equilibrium.

*asked on February 12, 2014* -
## Drug Abuse and Addiction

I need research sources for drug abuse and addiction. Thank you. Check these sources -- http://www.nida.nih.gov/ http://teens.drugabuse.gov/ (Broken Link Removed) http://www.drugabusestatistics.samhsa.gov/

*asked on November 12, 2006* -
## physics

During a rockslide, a 520kg rock slides from rest down a hillside that is 500m long and 300m high. The coefficient of kinetic energy between the rock and the hill surface is .25. a) If the GPE energy U of the rock –Earth system is zero at the bottom of

*asked on January 10, 2007* -
## Calculus

A piece of wire 40 m long is cut into two pieces. One piece is bent into a square and the other is bent into an equilateral triangle. How should the wire be cut so that the total area enclosed is a maximum= minimum= Find the length of the wire used

*asked on May 7, 2013* -
## physics

Approximately 5.5 X10^6 kg of water fall 50m over Niagara Falls each second. a) What is the decrease in the gravitational potential energy of the water-Earth system each second? b) If all this energy could be converted to electrical energy (can’t happen)

*asked on January 11, 2007* -
## english

15. Identify the sentence in which the underlined pronoun is used incorrectly. There are only six days left in the school year. It will be fun to visit their house in the summer. Their just going to have to wait to see the movie. Greg refused to go there

*asked on April 10, 2015* -
## Chemistry, empirical formula

Determine the empirical formula for the following compounds with these compositions (by mass): a) Cr 47.7% F 52.3% b) Na 42.1% P 18.9% O 39.0%

*asked on September 23, 2014* -
## English

Nine Haikus During a Drought In the dusty lane A frog waits for a puddle To fall from the sky Which form best describes this poem? A. limerick B. Haiku C. Concrete D. Narrative My choice is B. Haiku What about the poem best supports the answer to the

*asked on February 18, 2016* -
## Chemistry (Electrochemistry)

The standard potential for the following galvanic cell is 1.72V : Be(s)|Be2+(aq)||Pb2+(aq)|Pb(s) The standard reduction potential for the Pb2+/Pb half-cell: E = -.13V Calculate the standard reduction potential for the Be2+/Be half-cell. What I know: Be is

*asked on December 5, 2014* -
## probability

1. Busy people arrive at the park according to a Poisson process with rate λ1=3/hour and stay in the park for exactly 1/6 of an hour. Relaxed people arrive at the park according to a Poisson process with rate λ2=2/hour and stay in the park for exactly

*asked on November 27, 2018* -
## programming

create the logic for a program that calculates and displays the amount of money you would have if you invested $5000 at 2 percent simple interest for one year. create a separate method to do the calculation and return the result to be displayed.

*asked on October 28, 2014* -
## Chemistry, HELP!!

a) If the volume of a flask is 165 mL and the mass of the vapor in the flask is 0.2136 grams, what is the density of vapor in the flask? b)If the temperature of the vapor is 25 degrees Celsius, what is the molecular weight of the vapor? (Assume the gas

*asked on September 23, 2014* -
## Precalculus

Every point in the plane has exactly two polar coordinates. A)The statement is true because every point in the plane has a unique polar representation. B)The statement is false because left parenthesis r comma theta right parenthesis equals left

*asked on January 12, 2017* -
## physics

The figure gives the acceleration a versus time t for a particle moving along an x axis. The a-axis scale is set by as = 15.0 m/s^2. At t = -2.0 s, the particle's velocity is 7.00 m/s. What is its velocity at t = 6.0 s?

*asked on February 6, 2015* -
## Organic Chemistry

When benzyl chloride is treated with sodium iodide in acetone, it reacts much faster than 1-chlorobutane, even though both compounds are primary alkyl chlorides

*asked on November 9, 2008* -
## Algebra 1

At takeoff, a plan flies at an angle of 10 debrees with the runway. After it has traveled a ground distance of 2,800 feet, find the vertical distance the plane has gained from takeoff. Round your answer to the nearest foot

*asked on May 10, 2012* -
## algebra

translate into algebraic expression 24 more than twice Greg's age

*asked on August 6, 2017* -
## Chemistry

Consider the titration of a 35.0-mL sample of 0.175 M HBr with 0.200 M KOH. Determine the pH after adding 5.0 mL of base beyond the equivalence point.

*asked on February 27, 2011* -
## Physics

We want to rotate the direction of polarization of a beam of polarized light through 90 degrees by sending the beam through one or more polarizing sheets.(a) What is the mini-mum number of sheets required? (b) What is the minimum number of sheets required

*asked on December 21, 2012* -
## 7th grade English

Both the authors of Zoos: Joys or Jails and the author of Why do we need Zoos : a. think animals should live in their natural habitat b.believe animals are protected in zoos c.wish people would make donations to zoos d. want to help wild animals, esp.

*asked on June 4, 2015* -
## Statistics

A random sample of forty-eight 200 meter swims has a mean of 3:12 minutes and a standard deviation of .09 minute. Construct a 95% confidence interval for the population mean time. I know u: 3.12, sx: .09, n:48, c:.95 What is the formula I use to find the

*asked on August 1, 2012* -
## Physics

Dry air will break down if the electric field exceeds about 3.0 × 106 V/m. What amount of charge can be placed on a capacitor if the area of each plate is 6.7 cm2?

*asked on February 28, 2013* -
## Chemistry

How many molecules of Cl2 would be formed from the reaction mixture that produces the greatest amount of products? Consider the following reaction: 4HCl(g)+ O2(g)to 2H2O +2Cl2(g)

*asked on September 28, 2010* -
## Calc I

if f(t)=sqrt(4t+1) find f''(2) I got the first derivative to be: 1/2(4t-1)^-1/2 * 4t^3 and i'm trying to figure out if i need the product rule again to find the second derivative -1t^3(4t-1)^-3/2 * 4t^3 The answer if -4/27 and I'm not sure how to get that

*asked on December 7, 2014* -
## ap chemistry

Find the emf for the cell Cr(s) |Cr3+(aq, 0.37 M) || Pb2+(aq, 0.0095 M) | Pb(s). Answer in units of V I got .548733V Is this right?

*asked on October 21, 2010* -
## physics

2. Explain how the tension force gets transmitted along from one end of a string to the other. Does the amount of force that gets transmitted depend on how elastic or stretchable the string is? Explain.

*asked on October 22, 2010* -
## Bus. Math 123

Problem: Invoice-Nov. 27. Date goods recvd. ? Terms- 2/10 EOM. Last day of discount- ? Final day bill is due ? Complete above.

*asked on July 29, 2017* -
## probability

Busy people arrive at the park according to a Poisson process with rate λ1=3/hour. Relaxed people arrive at the park according to an independent Poisson process with rate λ2=2/hour. Assume that no other people arrive at the park. During the last 10

*asked on November 27, 2018* -
## chemistry

Calculate the [H3O + ] for 0.42 M HCl. Answer in units of M.

*asked on March 23, 2011* -
## math

A financier plans to invest up to $500,000 in two projects. Project A yields a return of 8% on the investment of x dollars, whereas Project B yields a return of 13% on the investment of y dollars. Because the investment in Project B is riskier than the

*asked on June 10, 2017* -
## math

A financier plans to invest up to $500,000 in two projects. Project A yields a return of 8% on the investment of x dollars, whereas Project B yields a return of 13% on the investment of y dollars. Because the investment in Project B is riskier than the

*asked on June 9, 2017* -
## Physics

How much work must be done to increase the speed of an electron (a) from 0.18c to 0.19c and (b) from 0.98c to 0.99c? Note that the speed increase is 0.01c in both cases.

*asked on December 12, 2012* -
## math

Solve the linear programming problem by the method of corners. Find the minimum and maximum of P = 3x + 2y subject to 3x + 5y ≥ 20 3x + y ≤ 16 −2x + y ≤ 2 x ≥ 0, y ≥ 0 The minimum is P = at (x, y) =

*asked on June 9, 2017* -
## Physics

A proton, moving with a velocity of vinitial i, collides elastically with another proton that is initially at rest. Assuming that the 2 protons have equal speeds after the collision, find (a) the speed of each proton after the collision in terms of

*asked on October 13, 2009* -
## Chemistry

Calculate the concentration of all species in a 0.15 M KF solution. Ka = 6.4 x 10-4 for HF.

*asked on February 27, 2011* -
## MATH

A photograph has been enlarged to three times its previous size. By what percentage has the size of the photograph increased?

*asked on March 8, 2014* -
## Calculus II

A cable that weighs 1.5 lb/ft is used to lift 700 lb of coal up a mineshaft that is 400 ft deep. Find the work done.

*asked on November 3, 2013* -
## Physics

Betty weighs 427 N and she is sitting on a playground swing seat that hangs 0.22 m above the ground. Tom pulls the swing back and releases it when the seat is 0.88 m above the ground. The acceleration of gravity is 9.8 m/s2. How fast is Betty moving when

*asked on February 20, 2013* -
## physical science

A golfer on a level fairway hits a ball at an angle of 38° to the horizontal that travels 85 yd before striking the ground. He then hits another ball from the same spot with the same speed, but at a different angle. This ball also travels 85 yd. At what

*asked on February 1, 2016* -
## Physics

7. An early objection to the idea that the earth is spinning on its axis was that the earth would turn so fast at the equator that people would be thrown into space. Show the error in this logic by calculating the centripetal force needed to hold a 100. kg

*asked on February 2, 2015* -
## Chemistry

A compound containing only carbon, hydrogen and oxygen is subjected to elemental analysis. Upon complete combustion, a .1804g sample of the compound produced .3051g of CO2 and .1249g of H2O. What is the empirical formula of the compound?

*asked on March 14, 2013* -
## Finance

You have just won the lottery and will receive $1,000,000 in one year. You will receive payments for 30 years, which will increase 5 percent per year. The appropriate discount rate is 8 percent. What is the present value of your winnings?

*asked on July 10, 2010* -
## probability

When you enter your bank, you find that there are only two tellers, both busy serving other customers, and that there are no other customers in line. Assume that the service times for you and for each of the customers being served are independent

*asked on November 26, 2018* -
## calculus

A patrol car is parked 50 feet from a long warehouse The light on the car turns at a rate of 30 revolutions per minute. How fast is the light beam moving along the wall when the beam makes the fol lowing angles with the line perpendicular from the light

*asked on November 3, 2016* -
## Chemistry Please help !

Carbon tetrachloride contains one carbon and four chlorine atoms. For this compound 11.818 g of chlorine combine with 1.000 g of C-12. Using this information, calculate the atomic mass of chlorine.

*asked on February 4, 2015* -
## ap chemistry

A solution is prepared in which a trace or small amount of Fe+2 is added to a much larger amount of solution in which the [OH]- is 1.0M*10^-2. some Fe(OH)2 precipitates. the value of Ksp for the salt is 8.0*10^-10. assuming that the hydroxide ion

*asked on October 19, 2010* -
## Physics

A 0.145 kg baseball pitched at 38.0 m/s is hit on a horizontal line drive straight back toward the pitcher at 55.0 m/s. If the contact time between bat and ball is 3.40×10−3 s, calculate the average force between the ball and bat during contact.

*asked on November 8, 2010* -
## Chemistry

What is the wavelength of an electron traveling at 7.59% of the speed of light?

*asked on March 14, 2013* -
## Calculus

Suppose the integral from 2 to 6 of g of x, dx equals 12 and the integral from 5 to 6 of g of x, dx equals negative 3 , find the value of the integral from 2 to 5 of 3 times g of x, dx

*asked on February 26, 2017* -
## Physics

Consider a situation where immediately after birth, twins are separated. One continues to live on earth, while the other is whisked away in a space ship at 90% of the speed of light. After 65 years they are reunited. Will they look the same? Show proof of

*asked on May 10, 2015* -
## Help Please!

Charges of −4q are fixed to diagonally opposite corners of a square. A charge of + 5q is fixed to one of the remaining corners, and a charge of + 3q is fixed to the last corner. Assuming that ten electric field lines emerge from the + 5q charge, sketch

*asked on January 24, 2011* -
## physics

A large box whose mass is 20 kg rests on a frinctionless floor. A mover pushes on the box with a force of 250 N at an angle of 35 degrees below the horizontal. What is the acceleration of the box across the floor?

*asked on January 16, 2011* -
## Science

How are are the viruses, bacteria, fungi, and protists similar? are the all living things or only visisble to through a microscope or infectious diseases??

*asked on January 6, 2014* -
## physics

A bullet was fired horizontally from the top of a 1.5x10^2 m tall tower at 2.8x10^2 m/s. Determine its speed on impact with the ground below.

*asked on September 23, 2013* -
## math

Sam has twice as many books as Jim. If Sam gives 12 books to Jim, they will have the same number of books. How many books to they have altogether?

*asked on March 26, 2017* -
## statistics

A college professor decides to run for Congress in a district with 450,000 registered voters. In a survey she commissioned, 58% of the 4000 registered voters interviewed indicated that they plan to vote for her. The population of interest is the: A.

*asked on January 31, 2009* -
## science

why do dry sodium chloride, the solutions of sodium nitrate and solution chloride all impart the same color to the flame?

*asked on April 16, 2019* -
## probability

Consider a Poisson arrival process with rate λ per hour. To simplify notation, we let a=P(0,1), b=P(1,1), and c=P(2,1), where P(k,1) is the probability of exactly k arrivals over an hour-long time interval. What is the probability that we will have “at

*asked on November 26, 2018* -
## physics

5. A bomber is flying at a height of 9 km at 800 km/h. How far in front of the target should he drop his bombs? show formulas*

*asked on November 28, 2012* -
## Physics

Visible light is incident perpendicularly on a diffraction grating of 200 rulings/mm. What are the (a) longest, (b) second longest, and (c) third longest wavelengths that can be associated with an intensity maximum at theta=30 degrees?

*asked on November 25, 2012* -
## calculus

Cars on a certain roadway travel on a circular arc of radius r. In order not to rely on friction alone to over come the centrifugal force, the road is banked at an angle of magnitude 0 from the horizontal. The banking angle must satisfy the equation rg

*asked on November 3, 2016* -
## math

Verify the given linear approximation at a = 0. Then determine the values of x for which the linear approximation is accurate to within 0.1. (Enter your answer using interval notation. Round your answers to three decimal places.)

*asked on October 20, 2013* -
## health

Identify at least five indicators of project failure that manifest themselves in this case study. Are these right ? these are a few i have came up with: organized inertia lack of clarity of pupose lack of landor project status report insufficient

*asked on September 13, 2010* -
## college

atoms heated in a sample emit only certain colors of light in sharp lines and not all colors blended together tells us what about the energy of an atom?

*asked on October 20, 2009* -
## math

A ferry boat operator is required to drive directly to the opposite side of the river (starting at south side of river is A and the north side of river is B where boat will end up) but does not know where to point the nose of the boat. The river is flowing

*asked on October 16, 2011* -
## probability

For each exam, Ariadne studies with probability 1/2 and does not study with probability 1/2, independently of any other exams. On any exam for which she has not studied, she still has a 0.20 probability of passing, independently of whatever happens on

*asked on November 26, 2018* -
## probability

Let X and Y be independent Erlang random variables with common parameter λ and of order m and n, respectively. Is the random variable X+Y Erlang? If yes, enter below its order in terms of m and n using standard notation. If not, enter 0.

*asked on November 26, 2018* -
## math

Use the formula t = (0.25) s1/2 to find the time t in seconds it will take a stone to drop a distance s of 200 feet. Round your answer to the nearest tenth of a second.

*asked on August 20, 2013* -
## Physics

If we intercept an electron having total energy 1533 MeV that came from Vega, which is 26 ly from us, how far in light-years was the trip in the rest frame of the electron? (Answer: 8.7*10^-3 ly)

*asked on December 15, 2012* -
## Chemistry

Two samples of water of equal volume are put into two dishes and kept at room temperature for several days. The water in the first dish is completely vaporized after 2.8 days while the water in the second dish takes 8.3 days to completely evaporate.What

*asked on November 18, 2010* -
## Finance

Suppose an investment offers to triple your money in 12 months (don't believe it). What rate of return per quarter are you being offered?

*asked on July 10, 2010* -
## math

Lead Contamination More than a decade ago high levels of lead in the blood put 88% of children at risk. A concerted effort was made to remove lead from the environment. In a random sample of 200 children taken more than a decade ago, what is the

*asked on November 20, 2009* -
## Physics... Please help me

A shell is shot with an inital velocity of 20m/s at an angle 60 degrees with the horizontal. At the top of the trajectory, the shell explodes into two fragments of equal mass. One fragment whose speed is immediately after the explosion zero falls

*asked on January 30, 2007* -
## Chemistry

Which element listed should have chemical properties similar to fluorine (F) A.Li B.Si C.Br D.Ne Br, along with F, a halogen (column 7 of the periodic table) Look at the periodic table. The columns are called groups. Elements in the same group have similar

*asked on November 9, 2006* -
## Chemistry

Calculate the total amount of heat that must be added to convert 15.7g of ice at its melting point to steam at 100.0°C

*asked on April 20, 2016* -
## Algebra

A rectangular Persian carpet has a perimeter of 212 inches. The length of the carpet is 24 inches more than the width. What are the dimensions of the carpet?

*asked on June 12, 2014* -
## AP Physics

Assume that at sea-level the air pressure is 1.0 atm and the air density is 1.3 kg/m3. (a) What would be the height of the atmosphere if the air density were constant? 7.919 km (b) What would be the height of the atmosphere if the air density decreased

*asked on December 3, 2009* -
## Pre-Calculus

How do I solve the equation: 3 = 2.1 sin[(pi/6)t - 5pi/6] + 3.2

*asked on February 19, 2017* -
## physics

Objects of equal mass are oscillating up and down in simple harmonic motion on two different vertical springs. The spring constant of spring 1 is 186 N/m. The motion of the object on spring 1 has 3 times the amplitude as the motion of the object on spring

*asked on March 30, 2012* -
## calclus

A fish is reeled in at a rate of 1 foot per second from a bridge 15 feet above the water. At what rate is the angle between the line and the water changing when 25 feet of line is out? (Assume the fish stays near the surface of the water.)

*asked on November 2, 2016* -
## Chemistry

6Li(s) + N2(g) 2Li3N(s) a) What mass of lithium is required to produce 0.575 g of Li3N in the balanced reaction? b) What mass of nitrogen is required for the reaction? ------------------------------------------- I tried dimensional analysis in a couple

*asked on March 8, 2015* -
## Physics

For a certain transverse wave, the distance between two successive crests is 3.11 m, and 5 crests pass a given point along the direction of travel every 12.16 s. Calculate the wave speed.

*asked on November 21, 2010* -
## earth science

what are risks associated with human-caused extinction?

*asked on December 11, 2018* -
## social studies

Which of the following statements about the natural resources of the United States is most accurate? A. The many agricultural resources of the United States have made up for its lack of other resources. B. U.S. industry and agriculture have prospered

*asked on December 23, 2013* -
## Ap Chemistry

Find the emf for the cell Cr(s) |Cr3+(aq, 0.37 M) || Pb2+(aq, 0.0095 M) | Pb(s). Answer in units of V I kept getting .55V but it is wrong. Can someone please help me?

*asked on October 21, 2010* -
## sociology

What is the best way to characterize the health care that the poor receive? inferior superior because of government insurance the same as care for wealthy people inferior only for the elderly poor about the same as for the average American

*asked on December 14, 2018* -
## Calculus

A spherical balloon is inflated with gas at the rate of 20 cubic feet per minute. How fast is the radius of the balloon increasing at the instant the radius is (a) 1 foot and (b) 2 feet?

*asked on November 2, 2016* -
## Math

Missing exponent of 1/169=(1/13) please explain how I can find the missing exponent

*asked on December 15, 2015*