Thursday
October 23, 2014

Posts by David


Total # Posts: 1,683

math
This is the Crailsheim water tower in Baden-Württemberg, Germany. Its construction was completed in 1912. The base of the tower is a graduated cylinder about 19.2 m high with a diameter of 11.5 m at the base and 8.1 m at the top. a)The spherical tank holds 4.08  ...
October 10, 2012

math
A regular triangular pyramid has an altitude of 15.0 m and the base is 8.00 m on a side. Find the area of a section made by a plane parallel to the base and 8.00 m from the vertex.
October 10, 2012

maths
A chemical engineer designed a 625 ft long tailings channel to have a rhombus cross-section that is 9.5 ft deep, with walls sloping at an acute angle of 44„a. A contractor placed a bid to excavate the canal at $195/cubic yard plus 20% profit. What was the bid?
October 10, 2012

physics
A pelican flying along a horizontal path drops a fish from a height of 6.0 m. The fish travels 7.7 m horizontally before it hits the water below. What was the pelican’s initial speed? The acceleration of gravity is 9.81 m/s 2. If the pelican was ...
October 9, 2012

physics
Janet jumps off a high diving platform with a horizontal velocity of 2.25 m/s and lands in the water 1.6 s later. How high is the platform? The acceleration of gravity is 9.8 m/s 2
October 4, 2012

Calc 3 PLEASE HELP!!!!
f(x,y,z)=xyz & 2xy+2xz+2yz=1300 & 4x+4y+4z=200 FIRST, simplify constraints: g(x,y,z)=xy+yz+xz=650 h(x,y,z)=x+y+z=50 THEN, take gradient vectors: for ▽f=<yz, xz, xy>=λ▽g+μ▽h =<λ(y+z), λ(x+z), λ(x+y)>+<μ, μ, &#...
October 4, 2012

calculus
If a rock is thrown upward on the planet Mars with a velocity of 13 m/s, its height in meters t seconds later is given by y = 13t − 1.86t2. (Round your answers to two decimal places.) (a) Find the average velocity over the given time intervals.
October 1, 2012

Physics
How do you find the v^2?
September 30, 2012

Physics
A mass m1 = 3.3 kg rests on a frictionless table and connected by a massless string over a massless pulley to another mass m2 = 4.4 kg which hangs freely from the string. When released, the hanging mass falls a distance d = 0.87 m. 1) How much work is done by gravity on the ...
September 30, 2012

math
Four boxes of cereal are to be selected at random from a continuous process that fills boxes labeled "Contents: 340 g." The contents of the first three boxes are found to weigh 339.0g, 337.7 g, and 338.9 g. (a) What minimum weight of cereal must the fourth box ...
September 23, 2012

physics
Before going into orbit, an astronaut has a mass of 55 kg. When in orbit, a measurement determines that a force of 67.1 N causes her to move with an acceleration of 1.1 m/s2. To regain her original weight, should she go on a diet or start eating more candy? To answer this, ...
September 23, 2012

physics
The net external force on a golf cart is 398.2 N north. If the cart has a total mass of 274.1 kg, what is the cart’s acceleration? Answer in units of m/s2
September 23, 2012

physics
The net external force on the propeller of a 3.6 kg model airplane is 8.4 N forward. What is the acceleration of the airplane? Answer in units of m/s2
September 23, 2012

Physics
A ball is thrown from a point 1.38 m above the ground. The initial velocity is 19.9 m/s at an angle of 33.8° above the horizontal. Find the maximum height of the ball above the ground. Calculate the speed of the ball at the highest point in the trajectory.
September 22, 2012

statistics
The director of an alumni association for a university wants to look at the relationship between the number of years since graduation and the amount of monetary contribution an alumnus makes to the university. He collects data on 50 alumni who have made contributions this year...
September 22, 2012

chemistry
Vacuum filtration is avoided when crystals are isolated from a very volatile solvent. why?
September 21, 2012

chemistry
The suction of a vacuum filtration apparatus is broken before the vacuum is turned off.give reason.
September 21, 2012

chemistry
An Erlenmeyer flask containing a hot solution is not tightly stoppered to prevent solvent loss during cooling. give reasons.
September 21, 2012

chemistry
A hot recrystallization solution is not filtered unless absolutely necessary.give reason.
September 21, 2012

Physics
A ball is thrown from a point 1.38 m above the ground. The initial velocity is 19.9 m/s at an angle of 33.8° above the horizontal. Find the maximum height of the ball above the ground. Calculate the speed of the ball at the highest point in the trajectory.
September 20, 2012

Chemistry
A chemist conducted a recrystallization on 18.5 g of a solid and collected 12.5 g from the first, and 2.7 g from the second recrystallization. Show your calculation and answer the following questions: What is the percent recovery in the first recrystallization? (1.5 marks) ...
September 20, 2012

Chemistry
• A student crystallized a compound from benzene and observed only a few crystals when the solution cooled to room temperature. To increase the yield of crystals, the students chilled the mixture in an ice-water bath. The chilling greatly increased the quantity of solid ...
September 20, 2012

Chemistry
Carborundum (silicon carbide) boiling chips are better than calcium carbonate chips in the recrystallization of an unknown,why ?
September 20, 2012

Chemistry
Carborundum (silicon carbide) boiling chips are better than calcium carbonate chips in the recrystallization of an unknown,why ?
September 20, 2012

Chemistry
The solubility of acetanilide in hot water (5.5 g/100 mL at 100C) is not very great, and its solubility in cold water (0.53 g/100 mL at 0C) is significant. What would be the maximum theoretical percent recovery from the first recrystallization of 0.5 g of acetanilide from 100 ...
September 20, 2012

Chemistry
Why can a water-ethanol solution be used for recrystallization but not a water-hexane solution?
September 20, 2012

Chemistry
The solubility of compound A in ethanol is 0.4 g per 100 mL at 0C and 5.0 g per 100 mL at 78C. What is the minimum amount of solvent needed to recrystallize an 8.0 g sample of compound A? How much would be lost in the recrystallization? Show your work.
September 20, 2012

Chemistry
After treating a coloured solution of a compound with activated charcoal, filtering and drying the product, the colour of the product was grey. What caused the grey colour? How can the grey colour be removed?
September 20, 2012

chemistry
explain the term carbonate error ..
September 17, 2012

Physics
A person walks the path shown below. The total trip consists of four straight-line paths. Path 1 is 40.0 m due east. Path 2 is 170.0 m due south. Path 3 is 120.0 m 30.0° south of west. Path 4 is 190.0 m 60.0° north of west. At the end of the walk, what is the person&#...
September 17, 2012

math
It is estimated that one third of one per cent of the Earth’s surface receives more energy from the sun than the total projected needs for the year 2014. Assuming the Earth’s surface to be 1.97 x 108 square miles. Find the area in acres.
September 16, 2012

Math
a/(a+2)-1 = -(3a+2)/(a^2+4a+4)
September 16, 2012

math
It is estimated that one third of one per cent of the Earth’s surface receives more energy from the sun than the total projected needs for the year 2014. Assuming the Earth’s surface to be 1.97 x 108 square miles. Find the area in acres.
September 13, 2012

math
How many liters of gasoline are there in 165 gal (US) of a methanol-gasoline blend that is 11.0% by volume?
September 13, 2012

math
A chemical distillation tower, 110 m high is supported by cables of length L that reach from the top of the column to the ground at a distance D from the base of the tower. If D is 1/3 the length of a cable, find L and D.
September 13, 2012

7th Grade Science
Identify 5 characteristics common to plants and describe them?
September 13, 2012

math
Write a number which rounds to 66,000 when rounded to the nearest ten thousand
September 12, 2012

psychology
when kevin started his car in the parking lot, he also turned on the radio to his favorite station,as he entered the street onto the campus, he turned the radio up due to the increased background noise in the car. entering the highway, he again increased the volume until he ...
September 12, 2012

math
Alex spent 3/7 of his money. He gave 1/4 of the remainder to his sister. He had $120 left. How much money did he have in the beginning?
September 11, 2012

physics
A roller coaster travels 196ft at an angle of 61.1° above horizantally. How far does it travel horizantally?
September 10, 2012

Math
an air traffic controller spots two planes at the same altitude flying towards one another. their flight paths form a right angle at point p. One plane is 150 miles from point p and is moving 450mph. the other plane is moving at 450mph but is 200 miles from point p. write the ...
September 9, 2012

Precalculus
an air traffic controller spots two planes at the same altitude flying towards one another. their flight paths form a right angle at point p. One plane is 150 miles from point p and is moving 450mph. the other plane is moving at 450mph but is 200 miles from point p. write the ...
September 9, 2012

Math
what does -1 E-4 mean when you write it out?
September 6, 2012

Physics
You are traveling on an airplane. The velocity of the plane with respect to the air is 110.0 m/s due east. The velocity of the air with respect to the ground is 39.0 m/s at an angle of 30° west of due north. 1) What is the speed of the plane with respect to the ground? 2) ...
September 5, 2012

algebra
(3,0),0,-4).solve for length, standard form.thank you
September 2, 2012

algebra
(3,0),0,-4).solve for length, standard form.
September 2, 2012

algebra
(3,0),0,-4).solve for the following :
September 2, 2012

Health
The answer is K ;)
August 29, 2012

Math
Find the half-life (in hours) of a radioactive substance that is reduced by 10 percent in 5 hours.
August 28, 2012

physics
A red ball is thrown down with an initial speed of 1.0 m/s from a height of 27.0 meters above the ground. Then, 0.6 seconds after the red ball is thrown, a blue ball is thrown upward with an initial speed of 24.5 m/s, from a height of 0.7 meters above the ground. The force of ...
August 27, 2012

Physics
A tortoise and hare start from rest and have a race. As the race begins, both accelerate forward. The hare accelerates uniformly at a rate of 0.8 m/s2 for 4.4 seconds. It then continues at a constant speed for 13.5 seconds, before getting tired and slowing down with constant ...
August 27, 2012

physics with 6 questions
Two cars start from rest at a red stop light. When the light turns green, both cars accelerate forward. The blue car accelerates uniformly at a rate of 3.3 m/s2 for 3.9 seconds. It then continues at a constant speed for 13.7 seconds, before applying the brakes such that the ...
August 27, 2012

Physic
Type A nerve fibers in humans can conduct nerve impulses at speeds up to 139.8 m/s. How fast is this in mph? This is a question from my physic homework. I have tried converting 139.8 m/s to mile then to hrs and i got .000241 mph. When I input it it said this is not correct. ...
August 26, 2012

physics
A rolling ball moves from x1 = 3.2 cm to x2 = -4.2 cm during the time from t1 = 3.8 s to t2 = 6.1 s. What is its average velocity?
August 23, 2012

math
Estimate. 247 * 974 a. Write your estimate as a number sentence: ________________ b. How I estimated : ________________________________
August 21, 2012

Stats
Question 3 Investment analysts generally believe the interest rate on bonds is inversely related to the prime interest rate for loans; that is, bonds perform well when lending rates are down and perform poorly when interest rates are up. Can the bond rate be predicted by the ...
August 20, 2012

Stats
This assignment requires you to use Excel. In question 1, you will use the charting features. In questions 2 and 3, use the regression tool from the analysis toolpack. There is no template for this assignment. Make sure you explain your answers and provide the regression ...
August 20, 2012

Math
Joelle earns her regular pay of 7.50 per hour for up to 40 hours a week. for each hour over 40 hours of work in a week, joelle is paid 1.5 times her regular pay. how much does joelle earn for a week in which she works 42 hours?
August 14, 2012

psychology
After watching golf on TV several times with her father, 7-year-old Michelle learned how to swing a club even before she actually had one in her hands. What kind of learning took place?
August 12, 2012

health
HAHAHA ME TOO THIS ANSWERS ARE REALLY HELPFUL THANKS
August 11, 2012

Physics
How long would it take a car engine, say 500 pounds of iron, to cool from 1,200 degrees F (exauhst manifold temp) to air ambient temp. of 75 degrees F.
August 10, 2012

Physic
What is the source of the sun's energy?
August 7, 2012

Stastistic
Finde the mean , variance , standard deviation N-127, P=0.66
August 6, 2012

math
Frank's cell phone package costs $20 per month and an additional $0.05 per text. Josie pays $15 per month and $0.10 per minute. Determine the linear system that could be used to find out when their monthly bills would be the same.
July 28, 2012

MATH
Find the amount of interest and the monthly payment for the loan. Purchase a living room set for $3,800 at 12% add-on interest for 3 years.
July 28, 2012

statistics
Surgery vs. placebo for the knee pain: Refer to Example 10. Is Arthroscopic Surgery Better than Placebo? Here we show MINITAB output comparing mean knee pain scores for the placebo (group 1) to debridement arthroscopic surgery (group 2). a) State and interpret the result of ...
July 28, 2012

Physic
What are some sources of energy that are available to heat the interiors of planets?
July 26, 2012

science
2 WAYS TO DETERMINE THE INTERIOR ARE GRAVITY, AND SEISMOLOGY.
July 26, 2012

Science
How can we use Kepler's laws or Newton's laws to learn about these objects?
July 26, 2012

Astronomy
How were the different objects in the solar system discovered? What are the properties of the ice giants?
July 26, 2012

Physic
alive
July 26, 2012

calculus
How do I take the partial derivative of P with respect to r of the following: D ~ P = ‡”(t=1 to T)[t ~ (CF)_t/(1+r)^t ]
July 7, 2012

math
5x-y=22 x+9y=32
July 6, 2012

Physics?
In Rutherford's scattering experiments, alpha particles (charge = +2e) were fired at a gold foil. Consider an alpha particle, very far from the gold foil, with an initial kinetic energy of 2.0 MeV heading directly for a gold atom (charge +79e). The alpha particle will ...
July 6, 2012

math
5040
July 6, 2012

Alg/Trig
(x-2)^2 + (y-3)^2 = 4.5^2
July 6, 2012

math ( pre algebra )
B. H
July 6, 2012

math
nonsense. let the three batteries by A,B,C then A = 2B 3A = C A + B + C = 54 so A = 12 B = 6 C = 36
July 6, 2012

math
How do I take the partial derivative of P with respect to r of the following: D × P = ∑(t=1 to T)[t × (CF)_t/(1+r)^t ]
July 6, 2012

Algebra 2
Thanks Ms Sue its my daughters problem ,my responce was maybe the wording might be asking "what investment " might be what amounts in what types of investments would yield the $4ooo. Or it might be just be about the math and analizing it. Either way ,thank you
June 5, 2012

Algebra 2
As a graduation present, you want to gift your son a trip to Disney World. Presently beginning his second semester as a high school junior, you hope you have enough time to save $4,000 to support much of the trips expenses for your child and two of his closest friends. Rather ...
June 5, 2012

english/grammar
I need help editing errors in parallelism in the following sentence: Is it true that Superman could leap tall buildings, run faster than a locomotive, and that bullets would bounce off his skin?
June 2, 2012

grammar
ops whats the first one
May 14, 2012

grammar
Whats the last one?
May 14, 2012

physics
or I've kept up with my homework and work this whole year except that our teacher just randomly decided to give us a ton of homework this weekend, and I have done all I can do. All of my friends are in the physics 1 class while this is physics 2 so no I cannot have answers...
May 13, 2012

physics
Hi, my teacher doesn't teach us too well and we have a few packets to hand in for tomorrow that I really don't understand much of. If someone could give me the answers to all of the problems on the first link if you search "the electrical energy converted to ...
May 13, 2012

Geometry word problem
A rectangular pond is 10m longer than it is wide. A walk 2m wide surrounds the pond. Find the dimensions of the pond if the area of the walk is 216m2
May 9, 2012

Geometry
A rectangualar playground is 4 meters longer than it is wide. If the length is increased by 5m, and the width decreased b y 1 m, the area is increased by 15m SQUARED(15M2).Find the original dimensions of the playground.
May 9, 2012

Math
How do i solve 2x+y > -3? And how do i graph it. This is Linear inequalities.
May 3, 2012

phisycal sciences
Which of the following properties did Rutherford use in his experiment? A. the negative charge of the alpha particles and the random distribution of protons B. the negative charge of the alpha particles and the positive charge of the gold foil C. the positive charge of the ...
May 3, 2012

Mathematics
Two numbers have thousandths other than zero. Could the difference of these numbers be 5.3? Explain.
May 2, 2012

algebra 2
Write an equation for a parabola with vertex at (3,- 6) and focus at (3,- 4).
May 2, 2012

chemistry
Is beta particles the answer?
April 30, 2012

chemistry
Which radioactive emanations have a charge of -1? beta particles alpha particles gamma rays neutrons
April 30, 2012

Algebra
-4x+1-2(x-1)= -4(x-4)
April 29, 2012

algebra
Write an equation of the hyperbola with foci (0, ) and (0, 2) and vertices of (0, ) and (0, 1).
April 29, 2012

spanish
Escribe el cual (la cual, los cuales, las cuales) o lo cual en el espacio. Nos invitaron a cenar con ellos, ____ fue una buena idea.
April 29, 2012

spanish
¿Cuál frase es correcta? El hijo del maestro, quien estuvo en mi clase, es muy inteligente. El hijo del maestro, a quien estuvo en mi clase, es muy inteligente.
April 29, 2012

algebra
When you spend $1 at the grocery store, the store doesn’t keep all of your money as profit. Some of it is reinvested in the economy when the grocery store buys more merchandise from suppliers. In turn, the suppliers don’t keep all of that money as profit, either; ...
April 28, 2012

Finance
Calculate the weighted cost of equity for a firm with the following characteristics: (a) Last Dividend--$5.00, (b) Growth Rate—6%, (c) Price of Stock--$125.00 and (d) Weight of Equity Capital—40%
April 27, 2012

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