Wednesday
July 23, 2014

Posts by TOM


Total # Posts: 1,050

Physics
What is the maximum theoretical efficiency of a steam engine operating between 60°C and 410°C?

Calculus
y=cos3x(sin^3)x

Calculus
derivative of y=tan^3(x)

Calculus
evaluate the limit: lim cos(x + pi/2)/x x->0

Calculus
Find the vector and scalar equations of the plane containing the line r=(3,5,1)+t(-2,3,1) and the point (1,2,3)

Physics
so 0.398/1.26 × 10^–6 m2=3.16x10^-7Pa

Physics
In a classroom demonstration, a 79.2-kg physics professor lies on a “bed of nails.” The bed consists of a large number of evenly spaced, relatively sharp nails mounted in a board so that the points extend vertically outward from the board. While the professor is lyin...

chem
If the density of copper is 8.92 g/ml what is the % error?

math
The exchange rate of U.S. dollars to British pound's is .63 you have $4000 to convert to British pounds. How many British pounds will you receive?

MATH HELP
A committee of 5 people is to be selected from student council. Council has 6 boys and 7 girls. What is the probability that the committee will have at least 3 boys? *** If you can show work that would be helpful (OPTIONAL)*** THANK YOU VERY MUCH!

MATH
A committee of 5 people is to be selected from student council. Council has 6 boys and 7 girls. What is the probability that the committee will have at least 3 boys? *** If you can show work that would be helpful (OPTIONAL)*** THANK YOU VERY MUCH!

Physics(work and energy)
but if i do that,then does it mean that i only supply 49000J to only overcome the work done agaist friction?

Physics(work and energy)
A cannon ball is fired so that it hits the wall at the top of a 10m tower.If the energy needed to destroy the wall is 49000 F and the mass of the cannon ball is 10 k, the minimum initial velocity of the cannon ball required to break the tower wall is A 100 m/s b 200 m/s c 300 ...

physics
A cat walks along a uniform plank that is 4 m long and has a mass of 7 kg. The plank is supported by two sawhorses, one 0.44 m from the left end of the board and the other 1.5 m from its right end. When the cat reaches the right end, the plank just begins to tip. What is the m...

physics
A trained dolphin leaps from the water with an initial speed of 12 m/s. It jumps directly towards a ball held by the trainer a horizontal distance of 5.50 m away and a vertical distance of 4.10 m above the water. In the absence of gravity the dolphin would move in a straight l...

Business Finance
Lisa Kane borrowed $8000 on an 8% 60 day note. After 15 days, Lisa paid $2000 on the note. On day 45, Lisa paid $1000 on the note. What is the total interest and ending balance due by the U.S. rule? Use ordinary interest.

Chemistry
The highest positive oxidation number that chlorine can exhibit an any compound is +7, whereas its most negative oxidation number is -1. Write the electron configuration of chlorine and explain why these are limiting oxidation numbers for chlorine.

Algebra
The body mass index I can be used to determine an individuals risk for heart disease. An index less than 25 indicates low risk. the formula for body mass index is I=700w/H^. W=weight and H=height, Jeromine is 67 inches tall. What weights will keep his body mass index between 2...

math
3/8 = .375 3/8<1 1% = .01 3/8%= .00375 .00375*$800= $3

math
13000/20000=(1-0.04t) (13000/20000)-1=-0.04t [(13000/20000)-1]/-0.04=t t=8.75

physics
Thanks Elena

physics
An electron enters a region where there is a magnetic field with a strength of 0.5 T which points out of the page (electron has an initial speed of 150 m/sec and is moving to the left). Describe motion of charge in an magnetic field (In particular, what is the shape of the pat...

English
What are the parts for the sentence "How many players are on a team?"

Stats
A manufacturer wants to increase the absorption capacity of a sponge. Based on past data, the average sponge could absorb 3.5 ounces. After the redesign, the absorption amounts of a sample of sponges were (in ounces): 4.1, 3.7, 3.3, 3.5, 3.8, 3.9, 3.6, 3.8, 4.0, and 3.9. What ...

Calculus 2 correction
I just wanted to see if my answer if correct the integral is: ∫(7x^3 + 2x - 3) / (x^2 + 2) when I do a polynomial division I get: ∫ 7x ((-12x - 3)/(x^2 + 2)) dx so then I use u = x^2 + 2 du = 2x dx 1/2 du = x dx = ∫7x - 12/2∫du/u - 3/1∫1/u = (7x^2...

Math
A bag of 12 white marbles and 1/3 red marbles and 2/5 blue marbles what is the total marbles in the bag?

Algebra 2
Abelardo wants to create several different 7-character screen names. He wants to use arrangements of the first 3 letters of his first name(abe, followed by arrangements of 4 digits in 1984, the year of his birth. How many different screen names can he create in this way? A.72 ...

Physics
the wind blows with a force of 425N north on a sail boat, while the water exerts a force of 325N west on the sailboat. Find the magnitude and direction of the net external force on the sailboat.

equation
4x + 3(29-x) = 100 please show work

Trig.
0 greater or equal to t greater or equal to 1.6

physics
A 4.5 cm tall object is placed 20 cm in front of a spherical mirror. It is desired to produce a virtual image that is upright and 3.5 cm tall. (a) What type of mirror should be used? concave mirror convex mirror (b) Where is the image located? (Your answer should be positive i...

science
If the greatest potential energy is 100J will the kinetic energy of the object ever reach 100J?

chemistry
If you have 4.90 moles of Ba, how many liters of N2 would you have at STP?

physics
Two blocks, A and B (with mass 50 kg and 100 kg, respectively), are connected by a string, as shown in the figure below. The pulley is frictionless and of negligible mass. The coefficient of kinetic friction between block A and the incline is &#956;k = 0.28. Determine the ...

math - calculus
The above answer is incorrect.. everything is right except v=9pi(h) differentiate both sides. gives you... dv/dt=9pi dh/dt 9/9pi= dh/dt. dh/dt= 1/pi

chemistry
The urine excreted by an adult patient over 24 hours was collected and diluted to give 2.000L sample. at ph 10 EDTA FORMS 1:1 COMPLEX WITH BOTH Mg2+ and Ca2+ and after buffering at this pH a 10mL aliquot of the sample required 26.81mL of 0.003474M EDTA for titration The Calciu...

math
I think I got it....11 weeks

math
Thanks for your help but I still don't get it

math
john has a 25 gallon fish tank. John filled his fish tank today with 24 gallons of water. the water evaporates at a rate of 1.5 gallons per week week. John adds 2 gallons to the tank every other week. At which of the following times will the tank contain 17.5 gallons? a. exact...

Organic Chemistry
How do you synthesize methysulfonyl benzene from Benzene?

ALGERBRA
Patricia owned so many posters that she decided to sell 63 of them to her friends. After selling the posters, she still had 172 left. Write and solve an equation to find the number of posters p Patricia had originally

physics
A mass m at the end of a spring vibrates with a frequency of 0.87 Hz. When an additional 602 g mass is added to m, the frequency is 0.59 Hz. What is the value of m?

algebra
Normally the largest area is enclosed by a square but this is only when the perimeter is 4 sides. In this problem the barn is the forth side with the 80 ft of fence used for only three sides. The complication is that the barn can contribute any lenght for its side. So the barn...

geom/trig
A 40 ft ladder leans against a wall so the base of the ladder is 11 feet away from the base of the wall . What angle does the ladder make with the wall?

Math
hello i need help for derivative: ( sin x ) / ( cos x ) thanks for your help

chem 2
What is the pH of a solution that consists of 0.50M H2C6H6O6(ascorbic acid) and 0.75M NaHC6H6O6(sodium ascorbate)? for ascorbic acid, Ka=6.8x10-5

Stats
Explain how to calculate margin of error. What effect does increasing your sample size have on the margin of error? What effect does it have on the confidence level? What effect does it have on the confidence interval?

Statistics
Explain how to calculate margin of error. What effect does increasing your sample size have on the margin of error? What effect does it have on the confidence level? What effect does it have on the confidence interval?

physics
A cylindrical object of volume V is immersed completely in a liquid.  is the density of the object and L is the density of the liquid. Write the expression for the buoyant force on the object, using these terms.

math
Answer is b.50

physics
A 1289 Hz sound from the speaker enters a tube at point A. It then takes two paths, ACD or ABD. Minimum sound is heard when ACD has a length of 94.2 cm and ABD has a length of 41.0 cm. The length of ACD is slowly increased until the point of maximum loudness is found when ACD ...

chemistry
You are a chemist requested to review and analyse certain debris found on thebottom of aboot found in a crime scene. The debris contains metal fragments. If you identify the metal fragments---it will help the detctive identify the locations traveled by the person who did the c...

chemistry
a large 1.5 x 10^6liter tank contains water polluted with lead (II) nitrate at a molarity concentraion of 2.5 x 10^-6 M to the tank, you add 59.7 liters of 0.075 M potasium chloride solution. did you add enough potassium chloride to remove all the lead(II) ions out of the solu...

Spanish-Please check
Thank you very much for correcting this-we're just learning this and I never thought it would be so difficult to do a conversation-thank you again

Spanish-Please check
Thank you for doing that

Spanish-Please check
We had to write a conversation in Spanish between a clerk and me wanting to buy pants I wanted them to be loose and I had to pay in cash Could you please check La dependienta: ¿En qué puedo servirle señor? La clienta: Busco los pantalones negro pero estos ...

physics
A 1093 kg van, stopped at a traffic light, is hit directly in the rear by a 715 kg car traveling with a velocity of +2.38 m/s. Assume that the transmission of the van is in neutral, the brakes are not being applied, and the collision is elastic. What is the final velocity of t...

CHEM
2) we know that gold is the thing we want.so use a method to have reaction with zinc but not gold. Hydrochloric acid is a good example. then use filter and filter paper to filter the gold out 3)AgCl is insoluble in water which is white in colour.its the white precipitate

physics
A 2.80 kg steel ball strikes a massive wall at 12.8 m/s at an angle of alpha = 50.9° with the plane of the wall. It bounces off with the same speed and angle. If the ball is in contact with the wall for 0.156 s, what is the magnitude of the average force exerted on the bal...

physics
Two men pushing a stalled car generate a net force of +698 N for 7.37 s. What is the final momentum of the car?

American History
C is the best answer

biology
Which nutrient functions BOTH as an enzymatic cofactor and as a stabilizer of ribosomes and nucleic acids? a) potassium b) phosphorus c) calcium d) Magnesium Thanks for your help!!

physics
A 690 kg elevator starts from rest. It moves upward for 2.56 s with constant acceleration until it reaches its cruising speed, 1.84 m/s. What is the average power of the elevator motor during this period? What is the power of the elevator motor during an upward cruise with con...

geometry
what equation represents the relationship of perimeter of a square varies directly as the length of it's side ?

pennfoster
Which of the following sentences contains a verb in the simple past tense? A. I was working overtime for about six months. B. She would like to join us. C. We helped Joan to pack her things. D. Jenna has driven this route multiple times

Physics
Hillary stands directly in front of speaker S1 and walks straight away (down on the page) What is the first distance (measured from S1) at which she will hear minimum loudness? Speed of sound is 341 m/s and the frequency of the sound is 496 Hz. The speakers are 2.07 m apart. n...

chemistry
the amount of heat when 65g of water at 100c until it cools to 37c

Physics
For finding Power, that's where I'll use 13kJ / 37,83 sec. right? = 343.64 watts.

Physics
so I was supposed to do Fres. X distance for 1 J = 1N*m. I had mixed the previous formulas up, I had the W for watts instead of Work. So my final answer for the work of the air resistance is actually 26N*500m = 13,000 J or 13 kJ. is that correct?

Physics
I just wanted to be sure if I got the answer right 1. Jenny (75 kg) goes on a ski trip. She goes down a slope that's inclined at 15*. Her drag coefficient is 0.300, the area of contact with the air is 0.750 m^2 and the air density is 1,31 kg/m^3. The coefficient of kinetic...

chemistry
A 100.0 gram sample of iron at 80.0 degrees Celsius was placed in 150 grams of water at 20.5 degrees Celsius. What was the final temperature when thermal equilibrium was reached?

chemistry
At 22 degrees Celsius and a pressure of 755 mm Hg, an unknown gas was found to have a density of 4.52 g/L. When analyzed, the gas was found to consist of two elements: Boron at 78.1% and Hydrogen at 21.9%. What is the molecular formula of this unknown gas?

Physics
Wrote the name and subject bad in the other post, sry:: Hello, this is the last question that I can't seem to be able to solve: 1. Jenny (75 kg) goes on a ski trip. She goes down a slope that's inclined at 15*. The drag coefficient of Jenny is 0.300, the surface of con...

calculus
Let f(x)=(x^2)+x+14. What is the value of f(x) for which the tangent line to the graph of y=f(x) is parallel to the x-axis?

Algebra 2
Dawn is writing a computer program to find the salaries of her employees after their annual raise. The percentage of increase is represented by p in the program. Marty's salary is $23,450 now. Write a polynomial to represent Marty's salary in one year and one to repres...

physics
A particle is displaced from the point ( 4 m, 12 m ) to the point ( 9 m, 1 m ) in 30 seconds. Calculate the direction (with respect to the positive x axis) of its average velocity vector.

math
29x47

math
For tax purposes, business frequently depreciate equipment.

Physics2
ok thank you drwls!

Physics
2 blocks are in contact on a horizontal table. A force is applied on the first block at a 30* angle. The blocks move to the right side. If m1 = 2kg and m2 = 1kg and F = 6 N kinetic friction at the middle of the 2 blocks and the table = 0.250 Find the "contact force" ...

MATH
the figure shows that the angle of elevation to the top of the building changes from 20 degree to 40 degree as an observer advances 75 feet toward the building. Find the height of the building to the nearest feet.

math
List at least one way in which a scalene triangle and equilateral triangle are the same.

math
List at least one way in which an acute triangle and an obtuse triangle are different.

Physics
v = fλ 23 m/s = 82Hz * λ λ = 23/82 λ = 0.28048780498 meters apart This one is correct

Physics
v = fλ 23 m/s = 84Hz * λ λ = 23/82 λ = 0.28048780498 meters apart

Physics
v = fλ 23 m/s = 84Hz * λ λ = 23/84 λ = 0.2738095238 meters apart

Physics
A car driving along a highway at a speed of 23 m/s strays onto the shoulder. Evenly spaced parallel grooves called “rumble strips” are carved into the pavement of the shoulder. Rolling over the rumble strips causes the car's wheels to oscillate up and down at a ...

Chemistry
a real gas would behave most like an ideal gas under conditions of

pre algebra
my numerator is a prime number My denominator is divisible by 2 i am equivalent to 1/5

Chemistry
What is the trend in atomic size in the series of Group IIA elements Be through Ra?

Physics
A record has an angular speed of 47 rev/min. Through what angle does it rotate in 1.07 s? Answer in units of ra

Excel-Exponential Fits
Hey Im trying to plot this set of data: 0 0 10 0.6 20 1.01 30 1.428 40 2 50 2.3 60 2.57 70 2.8 80 3.05 90 3.35 100 3.54 110 3.73 120 3.9 130 4.08 140 4.25 150 4.39 160 4.53 170 4.65 180 4.754 190 4.846 200 4.943 210 5.011 220 5.111 230 5.175 240 5.23 250 5.295 260 5.356 270 5....

Calculus (2)
oh I get it now, tnx!

Calculus (2)
and how do you get (x+1)?

Calculus (2)
Tnx for the quick answer, but I still have a question: why is it - in y' = e^-x (-) (x+2)e^-x instead of a + ?

Calculus (2)
find the first and second derivative of: f(x) = (x+2)/e^x I get to: f'(x) = e^x - (x+2)(e^x) / (e^x)^2 I'm stuck at that

calculus
last one is supposed to be dy/dx = 1 / ((e^y^2 * 3y^2) - (9^xsin(3y)ln3) - (1+3y))

calculus
considering that x is the independent variable in this equation: y + y^3 + 3 = e^y^2 + 3^x * cos(3y) - x Evaluate dy/dx I get to: dy/dx (1+3y) = e^y^2 * 3y^2 * dy/dx + 3^x * ln3 * (-sin(3y)) * 3 *dy/dx -1 Will it give me? dy/dx(1+3y) = dy/dx((e^y^2 * 3y^2) + (3^x * ln3 * (-sin...

Organic Chemistry
What is the mechanism for the removal of bromine from dibromocholesterol using Zinc and acetic acid?

Math
In Mrs Halls class of 30 students, 17 have computers at home and 20 have cassettes. If 4 students in the class have neither a computer or a cassette, how many of the 30 students have both?

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