Sunday
December 4, 2016

Posts by dave

Total # Posts: 818

science
1. How much potential energy does a 5kg block have if it is 2m above the ground? 2. What is the mass of an object that has 40J of potential energy and is 10m above the ground? 3. What is the weight of an 8kg object? 4. How much work does it take to lift an 8kg object 2m? 5. ...
October 22, 2011

physics
A container of hot water at 80 deg C cools to 79 deg C in 15 seconds when it is placed in a room that is at 20 deg C. Use Newtons law of cooling to estimate the time it will take for the container to cool from 70 deg C to 69 deg C.
October 19, 2011

physics
A container of hot water at 80 deg C cools to 79 deg C in 15 seconds when it is placed in a room that is at 20 deg C. Use Newton's law of cooling to estimate the time it will take for the container to cool from 70 deg C to 69 deg C.
October 19, 2011

college math
find the slope of the tangent line to the graph of f at the given point. Graph f and the tangen line. 9. f(x) = 3x +5 at (1.8) 10. f(x)=2x + 1 at (-1,3) Please, help me with this problems. thanks
October 19, 2011

math
a1=8,d=3,n=16 the one is a little below the a
October 16, 2011

Physics
25 Newtons
October 13, 2011

Investment
1.If a stock's return has a large standard deviation, that suggests the stock has little risk is tru or false. 2.If the return on two stocks is highly and positively correlated(i.e., correlation coefficient=+1.0), combining these stoocks will reduce the risk associated ...
September 30, 2011

english
can u help me with this rhyme? small parts of wild plants it's dealing with possessive nouns
September 23, 2011

physics
A ball, initially at y = 0, is thrown straight down and takes 1.40 s to move 13.8 m in the - y direction. Calculate the initial velocity of the ball.
September 22, 2011

physics
A figure skater is warming up on the rink. She does a lap of a 100m rink. She completes the laps in 3 minutes. What was her speed? Answer a. 33.3 m/min b. 300 m/min c. 66.7 m/min my answer b.300 m/min ?????
September 19, 2011

physics
What is the velocity of a car going east for 50 miles in one hour? my answer. 50 miles/hour (east)?????
September 19, 2011

physics
A figure skater is warming up on the rink. She does a lap of a 100m rink. She completes the laps in 3 minutes. What was her speed? Answer a. 33.3 m/min b. 300 m/min c. 66.7 m/min my answer b. ?????
September 19, 2011

physics
A figure skater is warming up on the rink. She does a lap of a 100m rink. She completes the laps in 3 minutes. What was her speed?
September 19, 2011

chemistry
From a 1M Tris solution, how is a 400ml of 0.2 M Tris prepared? I have no idea where to start
September 18, 2011

physics
a. .18
September 17, 2011

Chemistry
Iron reacts with HCl solution to give H2 gas and Fe2+ ions. Suppose that 5.3 g of iron are to be dissolved in 1.7 M HCl. What is the minimum volume (in mL) of the acid solution required to react with all of the iron?
September 11, 2011

Prob and Stats
The Roper Organization conducted identical surveys 5 years apart. One question asked of women was Are most men basically kind, gentle, and thoughtful? The earlier survey revealed that, of the 3,000 women surveyed, 2,010 said that they were. The later revealed 1,530 of the 3,...
September 5, 2011

bio
0.49
August 20, 2011

Physics
Where does V^2/g come from?
August 9, 2011

Physics
drwls - Your answer isn't correct either. The horizontal distance traveled is V*cos 45*t + Vj*t, and the time it takes for the grenade to reach the ground is SQRT(2Vsin45/g)
August 9, 2011

economics
Assume a monopolist with the following demand and cost relationships. Q = 400 - 20p TC = 10 + 5q + q2 Calculate the following: Profit max price Profit max quantity TR, TC, Profit, and the elasticity at profit max q and p.
June 23, 2011

geometry
The midpoint of mc is G. If AT = 42 and AG = 2x – 5, what is x?
June 17, 2011

trig
Why are the quadrants situated and numbered the way they are.What is the purpose.
June 13, 2011

World History
This man was responsible for the painting of the Sistine Chapel, as he spent 4 years lying on his back atop a scaffold , just a few feet from the ceiling.?
June 9, 2011

world history 10
A COW???
June 9, 2011

world history 10
boats ships???
June 9, 2011

world history 10
What transportation vessel and animal are on the family crest of the McDonalds of Scotland ? (Mr. G's ancestors)
June 9, 2011

Math
Add fraction and mixed numbers and reduce to lowest term 9 2/3 3 2/5 3/4 Can someone explain how to solve?
June 2, 2011

College math
What is the probability without replacement of drawing at least one ten (52 card deck)?
May 2, 2011

Physics
a 1.75kg pistol lies at rest on an essentially frictionless bench. it accidentally fires and shoots a 25 gram bullet parallel to the bench. How far has the bullet moved by the time the gun has recoiled 2.60mm?
April 25, 2011

algebra
x+(xtimes.15)=1725
April 20, 2011

College Physics
I'm asked to find the shortest wavelength photon emitted for the paschen series for the hydrogen atom. I used the Rydberg equation and substituted the appropriate values. Frequency= Rh(1/3^2)-(1/infinity^2) I get an answer of 820 nm. My online homework program said this ...
April 19, 2011

Algebra
yolo
April 14, 2011

calculus
I need a step-by-step limit definition of derivative for y = ln(x).
April 13, 2011

math
11
April 2, 2011

spanish
Answer the questions negatively, using the imperfect tense. Make sure to include the direct object pronoun when needed. Follow the model. Modelo ¿Juega Daniel al fútbol? No, pero antes lo jugaba. ¿Hablas por teléfono? No hablaba ¿Fue a la ...
March 31, 2011

Chemistry
what is the equation for the reaction of Cu(NH3)subscript2(SO4) with NaOH?
March 16, 2011

spanish
. Hay una variedad de las bebidas y los postres deliciosos también My teacher marked that sentence down, and according to her there is suppose to be a verb between postres and deliciosos, which i am having trouble figuring out. Can any one help?
March 9, 2011

engineering
If a pogo stick was to be reinvented and you were to choose the spring type. What type of spring will generate the most return of kinetic energy compared to least amount of force needed to compress the spring...you can use leaf, coil, scissor, compression, or extension type ...
March 7, 2011

Physics
hi, don't know the answer, i didn't even go to college.... i am trying to invent a device that will aid in handicapped sports... i am trying to load a spring with the least amount of energy and compound it into the highest kinetic force i can.. only thing loading this ...
March 5, 2011

pre-calculus
please help me with thisone thanks solve the inequality algebraically. Express the solution in interval notation. (x-8)^2/x^2-36 > 0
March 1, 2011

Physics
Part 1 You are a pirate working for Dread Pirate Roberts. You are in charge of a cannon that exerts a force 10000 N on a cannon ball while the ball is in the barrel of the cannon. The length of the cannon barrel is 2.47 m and the cannon is aimed at a 42degrees angle from the ...
February 27, 2011

Physics
The initial kinetic energy imparted to a 0.1 kg bullet is 1036 J. The acceleration of gravity is 9.81 m/s2 . Neglecting air resistance, find the range of this projectile when it is fired at an angle such that the range equals the maximum height attained. Answer in units of km.
February 27, 2011

Physics
Rosie (mass 58 kg) pushes a box with a horizontal force of 120 N (26.976 lb) at a speed 25 m/min. What is Rosie’s power output? Answer in units of W
February 27, 2011

Physics
A 1760 kg car accelerates uniformly from rest to 8.8 m/s in 4.52 s. Find the work done on the car in this time. Answer in units of J.
February 27, 2011

Physics
A block of mass 5 kg, which has an initial speed of 3 m/s at time t = 0, slides on a horizontal surface. Find the magnitude of the work that must be done on the block to bring it to rest. Answer in units of J.
February 27, 2011

Math
do adult men go out to dinner alone more than adult women and what is the percentage of men versus women women dine alone?
February 24, 2011

spanish 4
César le da consejos a un amigo en su primer día de trabajo porque el director de la cadena tiene muy mal humor. Escucha los consejos y cámbialos a mandatos. Sigue el modelo. Play audio For number 1 this is what the person says 1)el siempre pide que hagas...
February 23, 2011

math
I need someone to help explain how this math problem works. I am not sure how to convert this fraction below to arrive at 100.8 degress. 7/25 .360 degrees=100.8 degrees How did this answer of 100.8 degrees come about in this equation?
February 23, 2011

Physics
Newtons second law is Force=mass(acceleration) F= 20 N m= 8 kg Newton (N)= kg.m/s^2 20N=8kg(a) a=2.5 m/s^2
February 21, 2011

math
Does anyone know how can I apply the Pythagorean Theorem to real world situations.
February 21, 2011

math
Having trouble with these pairs of numbers (20,21,29) - (28,45,53) I am supposed to develop a Pythagorean triple. Here is that I am supposed to use which is a formula that can be used to generate infinite number of generating Pythagorean triples is: a = (2mn); b= (m^2 - n^2...
February 21, 2011

math
Could someone please describe two main differences between classical and empirical probabilities.
February 17, 2011

math
I do not know how to answer this question. Would someone please help me with each of the four question below? Thank you. Question 1. Write the sample space for the outcomes of tossing three coins using H for heads and T for tails. Question 2. What is the probability for each ...
February 17, 2011

math
This is what I am trying to solve for - x2 – 2x – 13 = 0 - x2 - 2x = 13 step (a): move the constant term to right side of the equation 4x2- 8x = 52 step (b): multiply each term of the equation by 4 times the coefficient of x2 – in this case 1x4 = 4 (trying to ...
February 13, 2011

math
In this equation 4(x^2 – 8x) = 4(13), what would the coefficient of x^2 be in this case? Would this be correct 4x1=4? If not, what would the correct answer be?
February 13, 2011

math
My problem I have involves a method that requires using the quadratic equations that comes from India. Here the problem that I have to solve : x to the second power plus 12x minus 64 equals 0 I need someone to walk me through each step to arrived to the answer for this problem...
February 13, 2011

Math
Can someone please help me to answer the following question? The question below has four choices, but only one correct answer. Could you please help me with the correct answer for this question? Thank you in advance. Question # 1. Find the slope of the line passing through the...
February 13, 2011

Diffeq
d/dx (x)(e^xy)(cos2x). Product rule lets me take the derivative of f(x)g(x). But three functions?
February 11, 2011

Math
Please Help! (R=restaurant) If R1 is 480-8t-0.8t^2 and R2 is 254+0.78t, how would I write a function (R3)that represents the total sales for the the two restaurants?
February 9, 2011

PreCalculus
(R=restaurant) If R1 is 480-8t-0.8t^2 and R2 is 254+0.78t, how would I write a function (R3)that represents the total sales for the the two restaurants?
February 9, 2011

maths
if two sides must be parallel then the fourth side is also 3.5 cm add the sides = perimeter
February 6, 2011

English
I would shy away from first person unless specifically to write from that perspective.
February 6, 2011

maths
1km = 1000 m 100cm = 1 m convert to meters and divide
February 6, 2011

math
check out law of cosines
February 6, 2011

chemistry
Fish-liver oil is a good source of Vitamin A. When 0.1232 g of fish liver oil is dissolved in 500. mL of solvent, an absorbance of 0.724 is recorded. When 0.00167 g of Vitamin A is dissolved in 250. mL of solvent, an absorbance of 1.018 is recorded. Calculate the mass percent ...
February 6, 2011

Math
The additive inverse is the # which when added to a number equals zero. If you consider 12 on the clock to be '0", the -3 and 9 would both have 3 as an "AI"
February 6, 2011

Physics
Thanks, I couldn't find an equation that derives the max velocity of the pendulum in my textbook.
February 5, 2011

Physics
Find the speed of a pendulum bob at the bottom of its swing if its initial displacement is 5 degrees and its period is 2 s.
February 5, 2011

Physics
Thanks. I was confused by the way the question was worded and my answer was 2 times bigger than what the answer is supposed to be.
February 5, 2011

Physics
A child of mass 40.0 kg is swinging on a swing with ropes of length 4.0 m. How long does it take the child to swing from the maximum height on one side to the other?
February 5, 2011

Science
equal, opposite
February 5, 2011

Social Studies (geography)
do a search for maps of the world / lat /long
February 5, 2011

Math
replace n with inf. 1 + (-1^0/0) = 1 +(-1^0) = 1+1= 2
February 5, 2011

Math
The additive inverse is the # which when added to a number equals zero. interesting questions. If you consider 12 on the clock to be '0", the -3 would have 3 as an "AI". If you consider the number you are starting from to be "0" then = or - 12 ...
February 5, 2011

STATISTICS
The experiment was not 'double blind" because the same person who compared the test scores (the professor) was aware of the reason for the experiment. If the groups were aware of the reason for them playing the games (possible affect on test scores) this would be ...
February 5, 2011

algebra
for every increase of 1 in x, y decreeases by 3 this gives us 3x y=0=23 so, y=23-3x
February 5, 2011

chemistry
ahh, of course, thank you.
February 5, 2011

chemistry
Consider a red flame color produced by excited lithium with a wavelength of 671 nm. What is the mass equivalent of 1 mol of photons of this wavelength? I can get as far as Js of E Can't seem to find equation to turn Js into mols, or photons into mols, for Js into photons. ...
February 5, 2011

Algebra
1 * 10^-3 = .001 1 * 10^-4 = .0001 1 * 10^-5 = .00001 Get the Idea?
February 5, 2011

science
what would happen if you mixed isopropanol with copper and dranked it
February 5, 2011

Calculus
y-(-4)= 5/2(x-3)-b this should be slope intercept FORM of what you wrote.
February 5, 2011

chemistry
what would happen if you mixed isopropanol with copper
February 5, 2011

Math 156
an infinity of shapes can have two right angles provided they have more than three sides and the sum of the inside facing angles minus the sum of the outside facing angles equals 180 degrees.
February 5, 2011

chemistry
h*c/lambda would this be planck's constant times speed of light / wavelength?
February 5, 2011

chemistry
An electron in the n = 5 excited state of a hydrogen atom emits a photon of 1281 nm light. To what energy level does the electron move? Any ideas on an equation for this? Is it some kind of backward version of Rydburg Eq?
February 5, 2011

MATH
correct. can be written as just 9s^2 - 4d^2
February 5, 2011

MATH
let x be ttl $ spent (2.75 * days) y=110-x
February 5, 2011

Math
You have two problems here. 1. need D:f(x) = 2sqrtx 2. subsitute x=4 into derivative D: 2sqrtx : a) multiply power times coefficient; 1/2 * 2 = 1 b)power - 1 = 1/2 -1 = -1/2 c. f'(x) = x^-1/2 or 1/sqrtx substitute 4 for x and you should be there
February 5, 2011

math
yup
February 5, 2011

physics
blocks A and B weigh 10 lb and 40 lb, respectively. A and B extend over a fixed drum, one on reach side. Determine the acceleration of A and the tension in the cord if the fixed drum is smooth.
February 3, 2011

Math
If a cube has one edge of 2m, what is the surface area of this cube?
January 17, 2011

chemistry
The heat of vaporization of a substance is 2900 J/g at its boiling point of 313C. How much of this substance can be vaporized if 58700 J of energy are available?
January 17, 2011

Math
What is the sum of the measures of the interior angles of an 11-side polygon?
January 12, 2011

Geometry
If ∆ ABC ~ ∆ DEF, BC = 12 cm, EF = 10 cm, and AC = 18 cm, find DF.
January 11, 2011

business
Your manager has asked that you reach out to three senior leaders in the organization to build a better understanding of their needs so that your department can better align themselves with these executives’ and build partnerships for new work. Where will you look for ...
January 10, 2011

earth
What does the word anti mean? My answer- is opposed to something????? Please help me
December 6, 2010

chemistry
I ALSO NEED HELP
December 6, 2010

Physics - bungee jumping
The gravitational potential energy of the jumper is mgh, where m is 60kg and h is 22m - 1.8m or 20.2m. The PE of the bungee at full length is 1/2kx^2, where x is the difference between stretched and unstretched length, i.e. 20.2m - 12.2m or 8m. Setting these to equal: 1/2kx^2=...
December 4, 2010

Math/Statistics
The mean starting salary for graduates in the spring of 2004 was $36,280. Assume that the distribution of starting salaries follows the normal distribution with a standard deviation of $3,300. What percent of the graduates have starting salaries between $35,000 and $40,000? a...
November 29, 2010

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