Tuesday
July 22, 2014

Posts by Amelie


Total # Posts: 50

physics
You observe someone pulling a block of mass 48 kg across a low-friction surface. While they pull a distance of 3.0 m in the direction of motion, the speed of the block changes from 4.9 m/s to 7.7 m/s. Calculate the magnitude of the force exerted by the person on the block. Thi...

Physics
Also, I know the rest energies would cancel out.

Physics
You observe someone pulling a block of mass 48 kg across a low-friction surface. While they pull a distance of 3.0 m in the direction of motion, the speed of the block changes from 4.9 m/s to 7.7 m/s. Calculate the magnitude of the force exerted by the person on the block. Thi...

Physics
In the approximation that the Earth is a sphere of uniform density, it can be shown that the gravitational force it exerts on a mass m inside the Earth at a distance r from the center is mg(r/R), where R is the radius of the Earth. (Note that at the the surface and at the cent...

College Physics
n the approximation that the Earth is a sphere of uniform density, it can be shown that the gravitational force it exerts on a mass m inside the Earth at a distance r from the center is mg(r/R), where R is the radius of the Earth. (Note that at the the surface and at the cente...

precalc
Oh, I forgot to add the negative sign with 3/7.

precalc
1. Get the inverse of each side in cos(θ)=-((3)/(7)). Cos^-1 (3/7) = theta. 2. From trig identities, we know sin2θ = 2sinθcosθ Substitute that in for sin2θ and just solve since you figured out θ in part 1 and you were given what cosθ equals, ...

Physics
A hanging wire made out of titanium with diameter 0.080 cm is initially 2.3 m long. When a 78 kg mass is hung from it, the wire stretches an amount 2.89 cm. A mole of titanium has a mass of 47.9 grams, and its density is 4.51 g/cm3. Based on these experimental measurements, wh...

Physics
One mole of tungsten has a mass of 184 grams, and its density is 19.3 grams per cubic centimeter, so the center-to-center distance between atoms is 2.51×10-10 m. You have a long thin bar of tungsten, 2.2 m long, with a square cross-section 0.16 cm on a side. You hang the...

math
Jim is able to sell a hand-carved statue for $670 which was a 35% profit over his cost. How much did the statue originally cost him?

math
The city council has decided to add a 0.3% tax on motel and hotel rooms. If a traveler spends the night in a motel room that costs $55 before taxes, how much will the city receive in taxes from him? I am studying for a exam, would you also know a good website for math review? ...

math
If Leah is 6 years older than Sue, and John is 5 years older than Leah, and the total of their ages is 41. Then how old is Sue? How do you know what and, is, and older mean in mathematical terms?

DNA
What nucleotide sequences do not code for proteins?

political science
How do local governments get their revenue in U.S.? and what are the sources?

Algebra
I am trying to simplify 24a^2/b^4 (the entire expression has a radical sign around it). I got 4a times the radical of 6a/b^4. However, my teacher said this isn't correct on my quiz. Why, and what is the right answer? Thanks!!!

Algebra
Yes, it is supposed to be a three, not a fourty three.

Algebra
I had to factor 5x^3-10x^2+43x-6. I got 5x(x^2+-2x)+3(x-2). My teacher said this was half right. What did I do wrong then? Thank you!!

Algebra
x^3+-448x?

Algebra
I am unsure how to factor x^3-8. Could you please explain?

Algebra
I'm sorry I mistyped my answer. I said it was 21x+4. What is wrong with THIS answer? Thanks.

Algebra
On my quiz for (3x+2)^2, I wrote the answer as 21x=4. My teacher gave me a minus one, which meant it was half wrong. What is wrong about my answer? Thanks

Algebra
I'm trying to solve the problem: 6y-bracket 3y-(y+7)bracket. I got an answer of 4y-7 multiple times. However, my book said the answer is 4y+7. I do not see how the 7 can be positive. I distributed the negative, so therefore, the seven should be negative. Or are parenthesis...

Algebra
I need to rationalize the denominator of 2/3 square root of five, (three being the index). My book suggests you should multiply this by 3 square root of 5^2 over 3 square root of 5^2. I thought the numbers that you rationalize the original with should be the denominator unalte...

chemistry
Dalton's Law states that the total pressure of a system is equal to the partial pressure of all the mixed gases. The equation looks like this. Ptotal = P1 + P2 + P3 + ... Assume that the temperature and volume is constant. When going to high altitudes, the pressure in a mo...

intro to probability
In a study of particulate pollution in air samples over a smokestack, X1 represents the amount of pollant per sample when a cleaning device is not operating, and X2 represents the amount per sample when the cleaning device is operating. Assume that (X1, X2) has a joint probabi...

intro to probability
For the sheet-metal stamping machine in a certain factory, the time between failures, X1 has a mean between the failures, of 56 hours and a variance of 16 hours. The prepair time X2, has a mean time to repair of 5 hours and a variance of 4 hours. a) If X1 and X2 are independen...

Intro to probability,
My main problem is deciding with discrete distribution to use: BERNOULLI, BINOMIAL, DISCRETE UNIFORM, GEOMETRIC NEGATIVE BINOMIAL, OR POISSON. Every time I choose one, it's the wrong one. Is there some way I can easily find out which one to use. Because what I do now is I ...

Probability
MY MAIN PROBLEM IS FIGURING OUT WHAT DISCRETE DISTRIBUTION TO USE, BERNOULLI, BINOMIAL, DISCRETE UNIFORM, GEOMETRIC NEGATIVE BINOMIAL, OR POISSON. Every time I choose one, it's the incorrect one. Is there some way I can easily find out which one to use. -------------------...

Intro to Probability
MY MAIN PROBLEM IS FIGURING OUT WHAT DISCRETE DISTRIBUTION TO USE, BERNOULLI, BINOMIAL, DISCRETE UNIFORM, GEOMETRIC NEGATIVE BINOMIAL, OR POISSON. Every time I choose one, it's the incorrect one. Is there some way I can easily find out which one to use. -------------------...

Intro to Probability
MY MAIN PROBLEM IS FIGURING OUT WHAT DISCRETE DISTRIBUTION TO USE, BERNOULLI, BINOMIAL, DISCRETE UNIFORM, GEOMETRIC NEGATIVE BINOMIAL, OR POISSON. Every time I choose one, it's the incorrect one. Is there some way I can easily find out which one to use. ------------------...

Intro to probability
thanks damon for your help

Intro to probability
Two balanced coins are tossed. What are the expected value and the variance of the number of heads observed? ================================== I'm confused on how to start. I don't know how many times im suppose to toss coin, and how to set up my table for the expecte...

Intro to Probability
thanks damon

Intro to Probability
thank you drwls for your help I greatly appreciate it.

Intro to Probability
two construction contracts are to be randomly assigned to one or more of 3 firms- I,II,III. A firm may receive more than one contract. if each contract has a potential profit of 90,000 dollars. find the expected potential profit for firm I. then find the expected potential pro...

Probability
thank you damon

Probability
posted twice, sorry

Probability
1.) An octave contains twelve different musical notes (in Western music). How many different eight note melodies can be constructed from these twelve notes if: (a) no note can be used more than once? (b) any note can be used as often as you please? ============================...

Intro to Probability, check some of my work please
1.) An octave contains twelve different musical notes (in Western music). How many different eight note melodies can be constructed from these twelve notes if: (a) no note can be used more than once? (b) any note can be used as often as you please? ============================...

Intro to Probability, please check my work.
thank you drwls

Intro to Probability, please check my work.
A fair coin is flipped three times. You win $5 every time the outcome is heads. Let the random variable X represent the total number of dollars you win. (a) List the sample space. (b) Determine the probability function of X. ====================== Answer: a) 2^3= 8 possibiliti...

Intro to Probability
Widgets are produced at a certain factory by each of three machines A, B and C. These machines produce 1000, 600 and 400 widgets per day, respectively. The probability that a given widget is defective is 4% for one produced by Machine A, 3% if produced by Machine B, and 2% if ...

Intro to Probability
In a certain election, the incumbent Republican will run against the Democratic nominee. There are three Democratic candidates, D1, D2 and D3, whose chances of gaining the Democratic nomination are .50, .35 and .15, respectively. Here are the chances that the Republican will w...

Intro to probability
An octave contains twelve different musical notes (in Western music). How many different eight note melodies can be constructed from these twelve notes if: (a) no note can be used more than once? (b) any note can be used as often as you please? ================================...

Intro to probability
oh, now wasn't that simple, thank you reiny

Intro to probability
A certain pizza restaurant offers three different sizes of pizza and eight different toppings. How many distinct pizzas having two different toppings can be made? ====================================== I think part of the answer to the question is (8)\ (2)/ where I choose 2 to...

Math: determinants
If det(A)=-7 A= | a b c | | d e f | | g h i | Find det(2A^-1), det((2A)^-1). Find | a g d | | b h e | | c i f |

Math: Factoring
I'm having a hard time factoring polynomials, especially 3rd degree. -x^3+2x^2+4x-8 -x^3-5x^2+20x+12 I don't know how to begin. I thought long division, but what would I divide by?

chemistry
Consider the following kinetic parameter for a given enzyme: Km=4.7x10-5 M Vmax= 22 nmol/min/mg [i]=5x10-1 mM [s]=2x10-4 M Ki=3x10-4 M Calculate the rate of product formation in the presence of a competitive inhibitor. I know that I have to solve for Vo. I also know that I nee...

Biochemistry
Consider the following kinetic parameter for a given enzyme: Km=4.7x10-5 M Vmax= 22 nmol/min/mg [i]=5x10-1 mM [s]=2x10-4 M Ki=3x10-4 M Calculate the rate of product formation in the presence of a competitive inhibitor. I know that I have to solve for Vo. I also know that I nee...

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