Sunday

January 25, 2015

January 25, 2015

Total # Posts: 302

**physics**

A hockey puck slides with an initial speed of 40.7 m/s on a large frozen lake. If the coefficient of kinetic friction between the puck and the ice is 0.038, what is the speed of the puck after 11.9 s?
*January 23, 2015*

**physics**

What would it mean if mu is greater than one?
*October 17, 2014*

**physics**

A 2.3 kg pendulum bob hangs from a 2 meter string. It is pulled to the side, position A, so that the bob is 111 cm (h on the sketch) above the lowest position, position C. The bob is released and begins to swing. See below. What is its potential energy after it has swung to ...
*October 16, 2014*

**physics**

Determine whether each statement below is true or false. The force necessary to lift an object is its mass times g. Kinetic energy is the energy of motion. Stopping distance is doubled, if speed is doubled. Work is the product of force and time. A joule is a newton times a ...
*October 16, 2014*

**physics**

A bow with a spring constant of 398 N/m has an arrow placed in it and pulled back a distance of 0.6 m. If the arrow is shot straight up in the air how high will it go? Assume the mass of the arrow is 0.16 Kg.
*October 16, 2014*

**physics**

A 63.8 kg woman lifts herself 36.6 cm each time she does a chin-up. What force does she exert in lifting herself to the chin position? And, how much positive work does she do in pulling herself up once?
*October 16, 2014*

**physics**

A crate rests on a flatbed truck which is initially traveling at 17.8 m/s on a level road. The driver applies the brakes and the truck is brought to a halt in a distance of 33.1 m. If the deceleration of the truck is constant, what is the minimum coefficient of friction ...
*October 2, 2014*

**physics**

A hockey puck slides with an initial speed of 52.3 m/s on a large frozen lake. If the coefficient of kinetic friction between the puck and the ice is 0.02, what is the speed of the puck after 11.8 s?
*September 26, 2014*

**statistics**

A politician claims that she will receive 65% of the vote in an upcoming election. The results of a properly designed random sample of 100 voters showed that 49 of those sampled will vote for her. Is it likely that her assertion is correct at the 0.05 level of significance? (a...
*June 11, 2014*

**math**

c=2πr c= 7.12 pi= 3.14 find value of r -rounded to 2 decimal points
*May 21, 2014*

**Physics**

I've been working on this problem for close to an hour now and keep getting very wrong numbers... The two objects with different mass (m1 = 5.0 kg and m2 = 3.0 kg) in the Atwood's machine shown in the figure are released from rest, with one object at a height of 0.91 m...
*April 20, 2014*

**Elementary Statistics**

There are 100 questions from an SAT test, and they are all multiple choice with possible answers of a,b,c,d,e. For each question, only one answer is correct, find the standard deviation for the numbers of correct answers for those who make random guesses for all 100 questions.
*April 11, 2014*

**problem solving - math**

the men are camping 45 miles due west and then go 60 miles directly north. if they can cover 18 miles a day how long will it take them to reach the railroad?
*October 3, 2013*

**problem solving - math**

timothy owns 13 chains, each chain having 3 links. timothy wants to use all the small chains to make one circular chain of 39 links. he needs 4 minutes to cut open a link and 10 minutes to close it by smoldering. timothy makes the big chain in 140 minutes. how?
*October 3, 2013*

**problem solving - math**

3 persons are to divide among themselves 21 equal cask, of which 7 are full, 7 are half full, and 7 are empty. how can an equitable division be made, without pouring the wine from any cask into any other, in such a way that each person receives the same amount of wine and the ...
*October 3, 2013*

**advance math**

an aquarium is in the shape of a right rectangular prism. each side of the aquarium is a rectangle that is 10 in wide and 8 in high. when the aquarium is tilted, the water in it just cover an 8 in by 10 in end, but only three-fourths of the rectangular bottom. find the depth ...
*October 3, 2013*

**discrete mathematics**

how many baseball games of single elimination must be played by 421 teams in a tournament before a winner is determined
*October 3, 2013*

**algebra**

that's my problem i do not know how to simplify.
*September 22, 2013*

**algebra**

a teacher reported 1/5 made A's, 1/4 made B, 1/3 made C's, 1/6 made D's, and 12 made F's How many are in the class Let X = the number of students 57/60 + 12 -------
*September 22, 2013*

**Science**

WHAT IS THE ANSWER FOR 4
*September 12, 2013*

**college physics**

a tennis ball is thrown straight up with an initial velocity of 22.5 m/s. it is caught at the same distance above the ground. a). how long does it take to reach its maximum height? b). how high does the ball rise? c). at what speed does it hit the ground? d). what total length...
*April 2, 2013*

**Chemistry**

Yes, I used it for my calculations. Thank you.
*March 19, 2013*

**Chemistry**

Oh wow. I just misread the standards the question was asking for. I was trying to make a 1.00M solution rather than a 1x10^-3M. I hope this is what my professor means with the way the question was written.
*March 19, 2013*

**Chemistry**

You have a stock 0.100 M solution of KMnO4 and a series of 100-mL volumetric flasks. What volumes of the stock solution will you have to pipet into the flasks to prepare standards of 1.00, 2.00, 5.00, and 10.0x10^-3M KMnO4 solutions? I tried using M1V1=M2V2 but the answers ...
*March 19, 2013*

**Calculus**

Thank you!
*February 28, 2013*

**Calculus**

I've been trying to solve the improper integral of ln(x)/sqrt(x) dx as a=1 and b=infinity I am required to solve for this question and according to my answer, it is divergent. However, my answer is infinity-4. Is it acceptable to say that infinity minus a number is simply ...
*February 28, 2013*

**Chemistry**

Awesome, thank you so much for the help!
*February 24, 2013*

**Chemistry**

I need help in solving this problem: A certain substance has a heat of vaporization of 42.46 kJ/mol. At what Kelvin temperature will the vapor pressure be 5.00 times higher than it was at 291 K? I know that I have to use the Clausius-Clapeyron equation, but what would I be ...
*February 24, 2013*

**Chemistry**

One of my homework problems deals with finding the change in entropy of the surroundings using the equation delta(S)= -delta(H)/T(temp.) The numbers given were T=263K and delta(H)fusion=6.0*10^(3) J/mol I know how to solve the problem, I just want to know why it is that even ...
*February 24, 2013*

**Calculus Problem**

Thank you so much for showing the steps, I really appreciate the help! (:
*February 15, 2013*

**Calculus Problem**

I need to find the integral of e^(2x)sin(3x) I used integration by parts and I let u=e^2x and dv=sin(3x) My final answer was (-3/8)(e^(2x))(cos(3x)) - (1/8)(e^(2x))(sin(3x)) but it's wrong. Please help!!
*February 15, 2013*

**Calculus**

Evaluate the definite integral. dx/(x*sqrt(lnx)) from 1 to e^4 I'm having trouble figuring this out, I might be overthinking it. The way I've approached this is by using u substitution and letting u=lnx. I keep getting the wrong answer though. Help is appreciated!!
*February 15, 2013*

**Calculus**

Figured it out. Turns out my b=4 not 2.
*February 9, 2013*

**Calculus**

The region between the graphs of x=y^(2)and x=2y is rotated around the line y=2. The volume of the resulting solid is... I've tried this five times and no luck. Please help. I think my a=o and b=2. I would appreciate the help.
*February 9, 2013*

**Calculus**

Never mind! I figured it out!
*February 9, 2013*

**Physics**

Which of the following equations describes the condition for observing the fourth bright fringe in Young's double-slit interference pattern? Assume n = 0 for the central bright fringe. Which of the following equations describe the condition for observing the fourth dark ...
*January 24, 2013*

**Physics**

Thank you so much
*January 24, 2013*

**Physics**

Okay so then 1(sin45) = 1.33(sinx) I got 32.04degrees?
*January 24, 2013*

**Physics**

What is the angle of refraction of a light ray that enters the surface of a calm lake from air at an angle of 45o to the normal? The refractive index of water is 1.333. I don't even know how to start this or what the formula is. Thanks for your help in advance. It really ...
*January 24, 2013*

**Physics**

A water wave is generated in a ripple tank by an oscillator that vibrates 50 times in 30 seconds. A given trough of the wave travels 50.0 cm in 15 seconds. What is the wavelength of the water wave? Produce all your workings. I got 50/30 = 1.67 vibrations per second = frequency...
*January 24, 2013*

**maths-urgent**

price of a home is 164,000. bank requires a 20% down payment and 3 points at closing. the cost of the home is financed with a 30 year fixed rate mortgage at 9%
*January 13, 2013*

**math**

In a right triangle, if sin ø = (5/13), what is the value of csc ø?
*December 14, 2012*

**Physics**

A person's body is producing energy internally due to metabolic processes. If the body loses more energy than metabolic processes are generating, its temperature will drop. If the drop is severe, it can be life-threatening. Suppose a person is unclothed and energy is being...
*December 7, 2012*

**college algebra**

that's what I got. thanks
*December 4, 2012*

**college algebra**

sorry that should be x^2+y^2+16x-18y+145=25 Been up to long working on this. Again I am sorry!!
*December 4, 2012*

**college algebra**

Can someone please help me find the x-intercepts and y-intecepts of this equation. I have the radius, and center but I can't seem to get the intercepts. x^2+y^2=16x-18y+145=25 Please show work. Thanks!!
*December 4, 2012*

**college algebra**

I am having to explain how to find the domain and range of a rational function from its graph. Can someone help me to try and put this into simple terms.
*November 30, 2012*

**college algebra**

find functions f anf g so that fog equals H H(x)=ãx^2+17 please show work
*November 30, 2012*

**college algebra, Please help!!**

find the domain of the composite function of fog f(x)=x^2+8;g(x)ãx-5
*November 30, 2012*

**college algebra, Please help!!**

solve the following equation 9^x-1 = 144(6x) please show work.
*November 28, 2012*

**college algebra**

use the properties of logarithms to find the exact value of the expression loglower 3^18 - log lower3^6 **how do I make the three lower in the log equation?
*November 27, 2012*

**college algebra**

solve the following exponential equation. 7^x=8 a. x= Write in exact solution b. then with that answer move the decimal 3 points over
*November 27, 2012*

**Physics**

On an extra note. I've done a lot of the practice problems and gotten those wrong... I don't know why I keep getting this wrong... But my answers for part a have been fairly close it seems like I keep getting my y-speed when the engine fails wrong by about 2.something ...
*November 24, 2012*

**Physics **

A rocket is launched at an angle of 56.0° above the horizontal with an initial speed of 103 m/s. It moves for 3.00 s along its initial line of motion with an acceleration of 31.0 m/s2. At this time its engines fail and the rocket proceeds to move as a free body. (a) Find ...
*November 24, 2012*

**Economics**

I am looking for an answer to this very same question with a different dollar amount "If the average adult produces $70,000 of output per year, how much output is lost annually as a result of adult deaths from secondhand smoke?" according to the news/study provided ...
*November 23, 2012*

**college algebra--need help please!!**

solve the equation in the real number system. 2x^4-23x^3+75x^2-88x+28=0 What are the real solutions of the equations? please show work. I do not know how to work this at all
*November 23, 2012*

**algebra**

use the rational zero theorem to list the potential rational zeros of the polynomial function. Do not attempt to find the zeros. f(x)=2x^7-x^5+8x^4+52
*November 20, 2012*

**college algebra--please help**

Find a bound on the real zeros of the polynomial f(x)=x^4+4x^3-8x-6 can someone help me, I am confused and don't know where to start.
*November 20, 2012*

**probability please help!!**

A fair, six-sided die is rolled eight times, to form an eight-digit number. What is the probability that the resulting number is a multiple of 8? Express your answer as a common fraction. I think the last 3 digits have to be divisible by 8 to be a multiple of 8...
*November 20, 2012*

**college algebra**

i am not understanding why you put 0 for the first answer. it doesn't seem like you added or did any type of math to get the 0. can you explain more. this is all confusing to me.
*November 20, 2012*

**college algebra**

we would let f(x)=x^3-7x^2+25x-39 = 0. we would factor to get (x-3)(x^ 2-4x+13). find the solutions to the second part (x^2-4x+13)using the quadratic formula. (the first part is x=3)
*November 20, 2012*

**social studys**

why do CHRISTIANS and MUSLIMS want the HOLY land? CHRISTIANS MUSLIMS HOLY
*November 20, 2012*

**social studys**

An estate of land, esp. one held on condition of feudal service
*November 20, 2012*

**probability - confused**

A fair, six-sided die is rolled eight times, to form an eight-digit number. What is the probability that the resulting number is a multiple of 8? Express your answer as a common fraction. I think the last 3 digits have to be divisible by 8 to be a multiple of 8...
*November 20, 2012*

**Chemistry**

For each of the bonds listed below use hybridized orbitals to classify the type of sigma bond that is formed between the two atoms. a) The sigma bond between boron and hydrogen in BH3 answer: sp^2 - p b) the sigma bond between S and fluoride in SF4. answer: sp^3d - p I ...
*November 7, 2012*

**General Chemistry**

An electron in a hydrogen atom relaxes to the n = 4 level, emitting light of 114 THz. What is the value of n for the level in which the electron originated? I am halfway through, but uncertain as to how to simplify the problem to completion. (6.63 x 10^-34 J x s)(1.14 x 10^14 ...
*November 1, 2012*

**Physics**

When the pendulum bob reaches the mean position, the net force acting on it is zero. Why then does it swing past the mean position?
*October 31, 2012*

**Physics**

Light cannot be linearly polarized by: transmission reflection diffraction diffraction
*October 29, 2012*

**Physics**

Which combination of primary additive colors will produce yellow-colored light? green and blue blue and red red and green cyan and magenta
*October 29, 2012*

**Physics**

Which of the following is an example of diffuse reflection? light reflected from the surface of a dry asphalt roadway light reflected from the surface of a calm lake light reflected from the surface of glossy paper light reflected from the surface of a shiny metal plate
*October 29, 2012*

**Physics**

When the pendulum bob reaches the mean position, the net force acting on it is zero. Why then does it swing past the mean position?
*October 23, 2012*

**Physics**

A tennis ball is dropped from 1.80 m above the ground. It rebounds to a height of 1.00 m (assume down to be negative). (a) With what velocity does it hit the ground? (b) With what velocity does it leave the ground? (c) If the tennis ball were in contact with the ground for 0....
*October 15, 2012*

**Advanced physical science**

An astronaut drops a golf ball to the surface of the moon from a height of 1.5m. The golf ball has a velocity of 2.24 m/s right before it lands on the moon (assume this height to be zero). What is acceleration due to gravity on the moon?
*October 4, 2012*

**Advanced physical science**

At the top of the Washington monument, a bird drops an acorn into the reflecting pool 169m below. If the acorn has a massof 1.0 kg, with what velocity would it hit the water?
*October 4, 2012*

**Advanced physical science**

A fiery ball of wood is loaded into a medieval catapult to be thrown into a castle. Unfortunately, the attacking heathens are not very smart and since geometry and physics were not studied in their time, they launched the ball straight up into the air. The catapult launcher ...
*October 4, 2012*

**APS**

The Marshmellow man tromps along the streets of New York City with his blue sailor hat on. He tries to climb up a building to reach Ghostbusters and a gargoyle statue falls 326m to the street below. What height is the gargoyle when it reaches a velocity of 59 m/s?
*October 4, 2012*

**APS**

Ben eats a bowl of rice as he walks across the San Francisco Bridge. When he is finished, he drops his empty bowl 67m down to the bay water. What speed does it hit the water with?
*October 4, 2012*

**chemistry**

Provide a synthesis of the following aldehyde starting from ethylene. Show the reagents and products for each step. H2C=CH2 --> CH3-CH2-CH=O Try to be as clear as possible. Thanks!
*August 31, 2012*

**Chemistry**

What alkane effuses at 1/5 the rate of He
*June 18, 2012*

**economics**

In the following examples, state how you would use the principle of marginal analysis to make a decision. a. Deciding how many days to wait before doing your laundry b. deciding how much library research to do before writing your term paper c. Deciding how many bags of chips ...
*June 1, 2012*

**Geometry**

I get it now! However, I think you made a mistake with .16=1-b^2/4. It should be turned into .64=1-b^2, and then b^2=0.36. Then x^2/4 + y^2/0.36=1.
*May 28, 2012*

**Geometry**

For an ellipse, one focus is (0,0), one vertex is (2,0), and the eccentricity is 0.4. How do I find the equation for the ellipse? It seems like I have so little information!
*May 28, 2012*

**Physics**

Thank you!
*May 20, 2012*

**Physics**

dev.physicslab. org/asp/nyregents/2003/January/part3.asp Why is the answer to #47 2 amperes? How do I get that?
*May 20, 2012*

**physics A**

A net charge of 47 mC passes through the cross-sectional area of a wire in 19.0 s. (a) What is the current in the wire? 1 A (b) How many electrons pass the cross-sectional area in 1.0 min? 2 . electrons
*May 16, 2012*

**Chemistry**

Thanks for the table! It actually is in my text, but I am taking the AP test soon, so I won't have a table like that. I can only answer the question based on the periodic table and that's it. Is there anything else I can use to at least eliminate the other choices?
*May 2, 2012*

**Chemistry**

Adding water to some chemicals can be dangerous because large amounts of heat are liberated. Which of the following does NOT liberate heat when water is added to it? KNO3 (the answer) NaOH Na CaO H2SO4 I guessed Na simply because it's the only one that's an element, ...
*May 2, 2012*

**Chemistry**

I think I get it, but just to clarify... Because we have a power supply, we know we have an electrolytic cell, which needs energy from an external source. For electrolytic cells, cathodes are considered the negative electrodes. If K+ and H20 go to the cathode, they get reduced...
*May 1, 2012*

**Chemistry**

A direct-current power supply of low voltage (less than 10 volts) has lost the markings that indicate which output terminal is positive and which is negative. A chemist suggests that the power supply terminals be connected to a pair of platinum electrodes that dip into 0.1-...
*May 1, 2012*

**Chemistry**

A 0.5224g sample of an unknown monoprotic acid was titrated with 0.0998M of NaOH. The equivalence point of the titration occurs at 23.82 mL. Determine the molar mass of the unknown acid.
*April 29, 2012*

**chemistry**

Hi Dr. Bob! I actually cleared it all up, but thank you!
*April 19, 2012*

**chemistry**

Hello, I have data here: tube # Contents Initial color (after 2 drops of universal indicator) Color after adding HCl Color after adding NaOH (after the HCl had been poured) 1 CO32-/HCO3- Dark purple Purple Purple 2 CO32-/HCO3- Dark purple -- -- 3 HCH3CO2/C H3CO2- red Light red...
*April 19, 2012*

**Chemistry**

Thanks so much! I get it now!
*April 10, 2012*

**Chemistry**

Hi Dr. Bob, When I do that, I get 11.30 as the pH, although I don't think that's it. Did I miss something?
*April 10, 2012*

**Chemistry**

HOBr (aq) <----> H+ (aq) + OBr- (aq), Ka = 2.3 x 10^-9 Hypobromous acid, HOBr, is a weak acid that dissociates in water, as represented by the equation. (a) Calculate the value of [H+] in a solution of HOBr that has a pH of 4.95. Ans: 1.1 * 10^-5 M (b) Write the ...
*April 10, 2012*

**Math**

Help with identify the property 45x6=(40+5)x(5+6)= I think Assoiative prop. ( is this correct?) 6x1=6 I put identity prop. of 1 4+(6+5)=(4+6)+5= distributive prop. 8+(-8)=0 I put identity prop. of 0 5x4=4x5 I put communtive property Can you tell me if I have them correct? Thanks
*March 28, 2012*

**math**

A sample survey of 50 people in Harrisburg, PA indicates that 10 of them know the mayors name in the neighboring city. Out of 5,500 Harrisburg residents, how many would you predict know the name of the mayor of the neighboring city? I thought 1100. I did 10/50=x/5500, is this ...
*March 28, 2012*

**physics **

A spherical conductor has a radius of 14.0 cm and charge of 26.0 µC. Calculate the electric field and the electric potential (a) r = 10.0 cm, (b) r = 20.0 cm, and (c) r = 14.0 cm from the center. how do i calculate k?
*February 7, 2012*

**physics HELP MEEE SO CONFUSED**

A spherical conductor has a radius of 14.0 cm and charge of 26.0 µC. Calculate the electric field and the electric potential (a) r = 10.0 cm, (b) r = 20.0 cm, and (c) r = 14.0 cm from the center.
*February 7, 2012*

**Physics**

I have to create a teaching aid for physics based on the principles i have learnt like gravitation , mechanical properties and many more. I am not able to find the right experiment to demonstrate infront of my teacher.Please help me deal with this by providing information ...
*January 26, 2012*