Sunday

December 21, 2014

December 21, 2014

Total # Posts: 812

**Chemistry**

I did the work, but I need help checking it... A compound contains 83.24% by mass carbon. Calculate the molar mass of the compound if it contains 5 moles of carbon per mole of compound. This was my process: I took 100g of compound and found that there are 83.24 g C in that ...
*January 26, 2012*

**Pre calc**

Use the half-angle formulas to determine the exact values of the sine, cosine, and tangent of the angle. 67° 30' 7 sin(67° 30')= cos(67° 30')= 4 tan(67° 30')=
*January 22, 2012*

**Chemistry**

Based on the balanced equation 2NBr3 + 3NaOH → N2 + 3NaBr + 3HOBr calculate the number of of excess reagent units remaining when 116 NBr3 molecules and 180 NaOH formula units react? I calculated the excess reagent to be NaOH. So is the units of remaining excess reagent 6...
*January 22, 2012*

**Chemistry**

A 0.7381 g sample of a compound containing C, H, and F was burned to produce 0.6368 g CO2 and 0.1303 g H2O. Calculate the empirical formula of the compound. Do I have to take in account the O atoms?
*January 21, 2012*

**Chemistry**

Is this correct? A 0.7473 g sample of a compound containing C, H, and O was burned to produce 1.909 g CO2 and 0.7813 g H2O. Calculate the empirical formula of the compound. I got C5 H10 O1. I'm not sure if that's correct..
*January 20, 2012*

**Physics**

Can an electric force between two point charges be negative?
*January 18, 2012*

**physics**

A woman pushes a crate along the floor of a warehouse with a force of 31.9 N directed downward at an angle of 23.6° from the horizontal. If the crate has a mass of 11.9 kg and the coefficient of friction is 0.0975, find... (a) the force of friction b. (b) theacceleration
*January 18, 2012*

**physics**

A woman pushes a crate along the floor of a warehouse with a force of 31.9 N directed downward at an angle of 23.6° from the horizontal. If the crate has a mass of 11.9 kg and the coefficient of friction is 0.0975, find... (a) the force of friction b. (b) theacceleration
*January 18, 2012*

**physics**

A woman pushes a crate along the floor of a warehouse with a force of 31.9 N directed downward at an angle of 23.6° from the horizontal. If the crate has a mass of 11.9 kg and the coefficient of friction is 0.0975, find... (a) the force of friction b. (b) theacceleration
*January 18, 2012*

**Physics**

3 charges are arranged along the x-axis. q1 = -4.50 nC is located at x = 0.200m q2 = +2.50 nC is located at x = -0.300m q3 = is a positive character located at the origin. What is the value of q3 for the net eletric force on it to be 4*10^-6 N? I found the charge on q3 to be...
*January 16, 2012*

**Chemistry**

If a sample of C6H4(CH3)2 is found to contain 3.54 * 10^26 CH3 groups how many moles of C6H4(CH3)2 molecules are present? C6H4(CH3)2 - 106.17 CH3 group - 15.035 C6H4 Group - 76.098 Please explain steps
*January 16, 2012*

**Chemistry**

Why did you divide .06 moles by 4? Is it because there is a 8:4 ratio of C and Co?
*January 16, 2012*

**Chemistry**

If a sample of Co2(CO)8 is found to contain 6*10^-2 mol of C atoms, how many grams of Co atoms are present? Molar Mass (g/mol) Co2(CO)8 - 341.95 Co atom - 58.933 C atom - 12.011 O atom - 15.999 Avaogadro's No.: 6.022*10^23 Do I need to use the 6*10^-2 mol of C atoms to ...
*January 16, 2012*

**Physics**

The 17500 Hz whine of the turbines in the jet engines of an aircraft moving with speed 280 m/s is heard at what frequency by the pilot of a second craft trying to overtake the first at a speed of 380 m/s?
*December 15, 2011*

**Physics**

A whistle of frequency 490 Hz moves in a circle of radius 2.00 ft at an angular speed of 15.0 rad/s. What are the lowest and the highest frequencies heard by a listener a long distance away at rest with respect to the center of the circle?
*December 15, 2011*

**Physics**

A whistle of frequency 490 Hz moves in a circle of radius 2.00 ft at an angular speed of 15.0 rad/s. What are the lowest and the highest frequencies heard by a listener a long distance away at rest with respect to the center of the circle?
*December 15, 2011*

**Physics**

The 17500 Hz whine of the turbines in the jet engines of an aircraft moving with speed 280 m/s is heard at what frequency by the pilot of a second craft trying to overtake the first at a speed of 380 m/s?
*December 15, 2011*

**calculus**

f(1)= 20, f(3)=13, f(5)=15, f(7)=16, f(9)=11, on [0,6] a, used midpint rule with n=5 to estimate intergral form 0 to 10 f(x)dx b, use trapezoidal rule with n=4 to estimate intergral from 1 to 9 f(x)dx c, used simpson's rule with n=4 to estimate intergal from 1 to 9 (x)dx
*December 12, 2011*

**College Physics**

A monatomic ideal gas with a pressure of 1.39x10^5 Pa and has a volume change of 260 L to a volume of 39.0 L. the second pressure is 3.28x10^6. How much work is done?
*December 7, 2011*

**Physics**

I'm having some trouble using these sites
*December 6, 2011*

**Physics**

A string along which waves can travel is 2.50 m long and has a mass of 203 g. The tension in the string is 26.0 N. What must be the frequency of traveling waves of amplitude 7.70 mm in order that the average power be 85.0 W?
*December 6, 2011*

**algebra**

what are two different word phrases for the expression t/30 ?
*December 5, 2011*

**Physics**

A 171-N child sits on a light swing and is pulled back and held with a horizontal force of 73.5N. The magnitude of the tension force of each of the two supporting ropes is?
*December 5, 2011*

**Physics**

A sinusoidal wave is traveling on a string with speed 30.00 cm/s. The displacement of the particles of the string at x = 15 cm is found to vary with time according to the equation y = (5.0 cm) sin[1.5 - (3.0 s-1)t]. The linear density of the string is 5.0 g/cm. (a) What is the...
*December 3, 2011*

**Physics**

I kinda wrote my equation wrong so heres a new version: y' = (0.30 cm) sin[(π/3 cm^(-1))x] cos[(55πs^(-1))t]
*December 3, 2011*

**Physics**

A string vibrates according to the equation y' = (0.30 cm) sin[(π/3 cm-1)x] cos[(55π s-1)t] What is the speed of a particle of the string at the position x = 1.5 cm when t = 9/8 s?
*December 3, 2011*

**Physics**

The equation of a transverse wave traveling along a very long string is given by y = 5.2 sin(0.013π|x + 4.7π|t), where x and y are expressed in centimeters and t is in seconds. (a) Determine the amplitude. (b) Determine the wavelength. (c) Determine the frequency. (d...
*December 3, 2011*

**Physics**

A string fixed at both ends is 8.71 m long and has a mass of 0.119 kg. It is subjected to a tension of 92.0 N and set oscillating. (a) What is the speed of the waves on the string? (b) What is the longest possible wavelength for a standing wave? (c) Give the frequency of that ...
*December 3, 2011*

**Physics**

Thanks I got it now.
*December 3, 2011*

**Physics**

A string fixed at both ends is 8.71 m long and has a mass of 0.119 kg. It is subjected to a tension of 92.0 N and set oscillating. (a) What is the speed of the waves on the string? (b) What is the longest possible wavelength for a standing wave? (c) Give the frequency of that ...
*December 3, 2011*

**Physics**

A wire 13.0 m long and having a mass of 80 g is stretched under a tension of 205 N. If two pulses, separated in time by 30.0 ms, are generated, one at each end of the wire, where will the pulses first meet?
*December 3, 2011*

**Physics**

Vibrations from a 650 Hz tuning fork sets up standing waves in a string clamped at both ends. The wave speed for the string is 410 m/s. The standing wave has four loops and an amplitude of 4.0 mm.
*December 3, 2011*

**Math**

Thank you Ms Sue.
*November 27, 2011*

**Math**

I found these web sites before but it does not tell me who it was. Please help.
*November 27, 2011*

**Math**

I have being trying to look up as to who invented the order of operations. Please help me.
*November 27, 2011*

**space**

I'm doing a solar system project for school. The problem I'm facing is that I'm am doing every two feet is 10 astronomical units, but how many 1/8 inch's is one astronomical unit?
*November 27, 2011*

**Math**

Write each percent as a decimal and as a fraction in simplest form. 5/8% would be .625% how do I make 5/8% into a fraction, or do I make .625% into a fraction.
*November 16, 2011*

**physics**

If an airplane propeller rotates at 1570 rev/min while the airplane flies at a speed of 333 km/h relative to the ground, what is the linear speed of a point on the tip of the propeller, at radius 1.97 m, as seen by (a) the pilot and (b) an observer on the ground? The plane'...
*November 9, 2011*

**Physics**

A flywheel with a diameter of 2.45 m is rotating at an angular speed of 74.1 rev/min. (a) What is the angular speed of the flywheel in radians per second? (b) What is the linear speed of a point on the rim of the flywheel? (c) What constant angular acceleration (in revolutions...
*November 9, 2011*

**Science**

An Olympic bobsledder pushes a 200 kg bobsled at 8 m/s. If the man pushes with a force of 1200 N, how much force of friction is present?
*November 8, 2011*

**college math**

factor 6y^4+2y^3
*November 7, 2011*

**physics**

Hello can you please help me with this investigation. I am having lots of problems with it can you please help. Thandeka wanted to investigate whether the number of vibrations per second depended on the length of the pendulum string. She sat up the apparatus. She pulled the ...
*November 5, 2011*

**English**

I have to write a Haiku with has to do with Science, please let me know if this is good. Science is great fun you get to use chemicals, but safety is first. Thank you.
*November 2, 2011*

**Chemistry**

Use Equation 7.1 and assuming that core electrons contribute 1.00 and valence electrons contribute nothing to the screening constant, S, calculate Zeff} for these two ions. Express your answers as integers. Enter your answers numerically separated by a comma. Equation 7.1: ...
*October 31, 2011*

**Genetics**

Sorry, not value.. I need an approximate length... in Angstroms.
*October 31, 2011*

**Genetics**

What is an approximate value of the length of a 30 nm fiber that contains 120,000 nucleotide pairs of DNA?
*October 31, 2011*

**math**

Yolanda and Yoko ran in a 100 yd dash. When Yolanda crossed the finish line, Yoko was 10 yd behind her. The girls then repeated the race, with Yolanda starting 10 yd behind the starting line. If each girl ran at the same rate as efore, who won the race? By how many yards. ...
*October 27, 2011*

**Physics**

At 7.65 cents per kilowatt-hour, what does it cost to operate a 8.00 hp motor for 7.00 hr?
*October 20, 2011*

**Calculus**

A rescue helicopter drops a crate of supplies from a height of 160 feet. After t seconds, the crate is 160 - 16t^2 feet above the ground. a) Find the velcocity of the crate at t=1 b) With what velocity does the crate strike the ground? for a do i just find the derivative and ...
*October 16, 2011*

**egd**

hi what notes go on the floor plan.can youu please help
*October 15, 2011*

**Physics**

If you drop a 1.0 kg weight from a height of 1.0 m, how many joules of kinetic energy will it have when it reaches the ground? Can I use the equation for work: W = F*s to find the kinetic energy? Or would I have to find the velocity of the weight as it falls because I'm ...
*October 10, 2011*

**Math Help!!!!!**

7x+3-2x
*October 6, 2011*

**Math Help!!!!**

7x+3-2x
*October 6, 2011*

**chemistry**

The density of a 2.45 M aqueous methanol solution is .976 g/ml. what is the mass of water present in 1.00 liter of this solution
*October 4, 2011*

**Physics**

You find it takes 230 N of horizontal force to move an unloaded pickup truck along a level road at a speed of 2.4 m/s. You then load up the pickup and pump up its tires so that its total weight increases by 42% while the coefficient of rolling friction decreases by 19%. Now ...
*October 4, 2011*

**Math**

The homothetic geometry on C is (C,H) where H is the group of scaling of C. Which figures are congruent in (C,H) to the circle of radius 1 centered at 1? How could you describe the congruence class in language understandable by a high school geometry student?
*October 3, 2011*

**information technolgy**

hi I have a project to do on netbeans but I am having problems.The project is you have to enter a message and there must be a encryption button,when you click on the encryption button the message must get encrypted.Can you help me out with the encryption code please!!!!!!!!!!
*October 3, 2011*

**Mathh !!!!! Help please !!!**

shut up
*October 2, 2011*

**german**

I have to finish a Paragraph about some event in the past and how I now reflect on it (have to use Präsens, Präteritum und Perfekt! I'm not too confident with this. We are also having a test tomorrow: "Here are the topics that you will encounter in the test...
*October 2, 2011*

**Physics**

A rubber ball dropped from a height of exactly 5 ft bounces (hits the floor) several times, losing 10% of its kinetic energy each bounce. After how many bounces will the ball subsequently not rise above 2 ft?
*October 2, 2011*

**geometry**

AB + BC = AC (2x-1)+(4x+2)=25 x=4 AB = 2(4)-1 = 7 BC = 4(4)+2 = 18
*October 2, 2011*

**egd**

I need information on a floor plan.The floor plan consists of 1 bedroom,bathroom & a kitchen.I need a design brief on how to draw it and what any other relavinet info.Please con you help!!!
*October 2, 2011*

**egd**

Hi I need help,I have to draw a floor plan of 1 bedroom house.Can you please help me out.
*September 30, 2011*

**Physics**

A man stands on the roof of a 15m tall building and throws a rock with a velocity of magnitude 30m/s at an angle of 33deg above the horizontal. Ignore air resistance. Calculate: a) the maximum heigh above the roof reached by the rock b) the magnitude of the velocity of the ...
*September 27, 2011*

**Physics**

A man stands on the roof of a 15m tall building and throws a rock with a velocity of magnitude 30m/s at an angle of 33deg above the horizontal. Ignore air resistance. Calculate: a) the maximum heigh above the roof reached by the rock b) the magnitude of the velocity of the ...
*September 26, 2011*

**information technolgy**

hi I need help with this question.how numbers such as isbn,id,student,work with ciphers.And i also needed simple information on ciphers.
*September 23, 2011*

**information technolgy**

Hi I need help trying to create a code to encrypt and decrypt a message in netbeans.I know what to do but I cant get it to encrypte and decrypte.Can you please help me.
*September 22, 2011*

**information technology**

Hi I need help trying to create a code to encrypte and decrypte a message in netbeans.I know what to do but I cant get it to encrypte and decrypte.Can you please help me.
*September 21, 2011*

**Information Technology**

hi I have an Information Technology assignment to do it is about a cipher.Can you help me to write out an java program about any cipher.I have tried out an program but it is not working.
*September 14, 2011*

**Chemistry**

622.5 not 662.5
*September 14, 2011*

**Math**

Ann, Mara, Jenny, Tina, and Sue are sisters. Two of the five sisters must help their father at his business each Saturday. How Many Combinations of two sisters are possible?
*September 13, 2011*

**Physics**

May my sacrifice be beneficial to the common good.
*September 13, 2011*

**Physics**

So answer = 4540! Yes physics 221 students, this answer was brought to you by my failure to complete Mastering Physics problem and ended up pressing the show answer button
*September 13, 2011*

**Physics**

Superman throws a boulder of weight 3500 N at an adversary. What horizontal force must Superman apply to the boulder to give it a horizontal acceleration of 12.7 m/s^2? F=? Fnet(x)=MA(x) I did (3500 N)(12.7 m/s^2) = 44450 N This answer is wrong. So what's up?
*September 13, 2011*

**IT(information technology)**

hi I have an IT assignment to do it is about a cipher.Can you help me to write out an java program about any cipher.I have tried out an program but it is not working.
*September 13, 2011*

**physics**

A skateboarder shoots off a ramp with a velocity of 6.8 m/s, directed at an angle of 54° above the horizontal. The end of the ramp is 1.3 m above the ground. Let the x axis be parallel to the ground, the +y direction be vertically upward, and take as the origin the point ...
*September 13, 2011*

**physics**

First you have to convert the miles into meters. There are 5280 feet in a mile, then there are 12 inches in a foot, then 2.54 centimeters in an inch and then 100 centimeters in a meter. So you should get ((262.4)(5280)(12)(2.54))/(100)= 422291.8656 meters. Speed= distance/time...
*September 13, 2011*

**information technology**

hi I have an IT assignment to do it is about a cipher.Can you help me to write out an java program about any cipher.I have tried out an program but it is not working.
*September 12, 2011*

**english**

hi I need help with an english question. Compare the island in the opening and closing chapters of the novel lord of the flies. About half a page
*September 12, 2011*

**english**

compare the island in the opening and closing chapters of the novel lord of the flies.
*September 12, 2011*

**math**

What is the average 3 point throw speed in basketball at professional level in meters per second?
*September 8, 2011*

**History**

Is fish considered a livestock in Texas?
*September 6, 2011*

**Physics**

Suppose that a NASCAR race car is moving to the right with a constant velocity of +92 m/s. What is the average acceleration of the car? (b) Twelve seconds later, the car is halfway around the track and traveling in the opposite direction with the same speed. What is the ...
*September 5, 2011*

**Physics**

A helicopter is lifting off from the ground and is moving vertically upward. The graph shows its vertical velocity vy versus time. How high is the helicopter after 12.0 s have elapsed?
*September 5, 2011*

**College Algebra**

The school play sold 498 tickets. Students paid $3.50 each, while non-students paid $5.50 each. If a total of $2121.00 was collected, how many students and how many non-students attended?
*September 1, 2011*

**math**

I do not understand this?
*August 25, 2011*

**math**

Find the mean, median, mode,range of each data. 1. 34,41,37,29,34 2. 9,21,93,31,31 3. 34,20,24,12,60 4. 74,92,67,45,67
*August 25, 2011*

**Math**

A contractor requires a cement mix that is 70% sand and 30% cement. He has 700 kg of a cement mix that is 80% sand and 20% cement. How much cement should he add so that he gets the required mix? My set up: required mix = (S)(.7) + (C)(3) 700kg = (S)(.8) + (C+X)(.2) Is this ...
*August 25, 2011*

**Physics**

A ball is thrown straight up in the air and passes a window 0.30s after being released. It takes 1.5s to go from the window to its maximum height and back down to the window. What was the initial velocity of the ball when it was released? I found where the ball would be after ...
*August 25, 2011*

**Math**

Sorry. It's supposed to be wall and how many walls they can paint in 1 day.
*August 24, 2011*

**Math**

Two employees are painting wall. A takes twice as long as B to paint the same area. During a typical 8-hour day, A works the full 8 hours, but B takes a 2-hour break. A paints one way in a day. How many walls do both employees paint together? I need an explanation on how to ...
*August 24, 2011*

**Physics**

Okay I understand the problem now and I got the answer right doing it your way. Thanks a lot for the explanation. It really helped!
*August 16, 2011*

**Physics**

Oh okay. I think this makes sense. Thanks for the explanation! For the first Vx, how come the 5.8 is negative?
*August 16, 2011*

**Physics**

But is centripetal acceleration the same as average acceleration? What's the point of the problem giving information about time if it's not even used in the process?
*August 16, 2011*

**Physics**

For no apparent reason, a poodle is running at a constant speed of 5.80 m/s in a circle with radius 2.3 m. For t_delta = 0.5 s calculate the magnitude of the average acceleration a_av. I have no idea how to start this problem because I'm trying to use this equation: a_av...
*August 16, 2011*

**us history**

give one example of how the action of an individual,group,or institution can affect society?
*August 14, 2011*

**science**

give one example of how the action of an individual,group,or institution can affect society?
*August 14, 2011*

**Physics**

Thank for you the explanation! But I'd like to ask, how come the last equation isn't V^2/g = 15.2 + 12(2Vsin45/g)?
*August 9, 2011*

**Physics**

In the latest Indian Jones film, Indy is supposed to throw a grenade from his car, which is going 43.8 m/s, to his enemy's car, which is going 55.8 m/s. The enemy's car is 15.2 m in front of the Indy's when he lets go of the grenade. A) If Indy throws the grenade ...
*August 9, 2011*

**Physics**

A baseball is hit with a speed of 27.0 m/s at an angle of 42.0 deg. It lands on the flat roof of a 10.0 m-tall nearby building. If the ball was hit when it was 1.0 m above the ground, what horizontal distance does it travel before it lands on the building...
*August 2, 2011*

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