# Posts by Laura

Total # Posts: 1,238

**Chemistry**

Phosphorus pentachloride decomposes according to the chemical equation: PCl5(g)<--> PCl3(g)+Cl2(g) Kc = 1.80 at 250 degrees Celsius A 0.352 mol sample of PCl5(g) is injected into an empty 4.45 L reaction vessel held at 250 °C. Calculate the concentrations of PCl5(g) ...

*March 8, 2013*

**math**

-3x+y-z=-10 -4x+2y+3z=-1 2x+3y-2z=-5 sorry.

*March 7, 2013*

**math**

solve the system of equations in three variables -3x+y-z=-10

*March 7, 2013*

**Fundamentals of math**

Thank you so much

*March 7, 2013*

**Fundamentals of math**

solve the system by substitution.. -3x-5y=-17 4x=y-8

*March 7, 2013*

**Theoretical&Experimental Probability please help!**

omg those are all wrong except number one. what the heck man. you need to study.

*March 6, 2013*

**physics**

Answer = A (1. No color, clear) Solids can be clear; ex: an ice cube Liquids can be clear; ex: water Gases can be clear; ex: Hydrogen gas Can't be #2 b/c liquids and gases do not scratch up wood. Can't be #3 b/c gases cannot and liquids do not have bumpy surfaces. Can...

*March 5, 2013*

**Chemistry**

Calculate the energy of a photon of frequency 35.0 MHz (MHz is a mega hertz or 1 x 106Hz).

*March 2, 2013*

**Trigonometry**

A water wheel has a radius of 15 ft. A river passing through the water wheel turns the wheel at 11 revolutions per minute(rpm). What is the speed of the river in miles per hour?

*February 28, 2013*

**Trigonometry**

A water wheel has a radius of 15 ft. A river passing through the water wheel turns the wheel at 11 revolutions per minute(rpm). What is the speed of the river in miles per hour?

*February 28, 2013*

**philosophy natural deduction**

1. ~(RvR) 2. I> (R*R) ~I

*February 27, 2013*

**Algebra**

I just did that question. its letter C

*February 26, 2013*

**Physics**

What can we say about the force of an object when the mass increases and acceleration remains constant?

*February 20, 2013*

**Physical Science**

A car and a truck are on the highway. Both need to accelerate at 7 m/s2 in order to avoid an accident. a. Find the force acting on the car, which has a mass of 408 k b. Find the force acting on the truck, which has a mass of 2,100 kg.

*February 20, 2013*

**Physical Science**

A force of 20 N is applied to a box of books with a mass of 4kg. Find the acceleration of the box of books.

*February 20, 2013*

**Algebra**

determine whether the pair of equations represents parallel lines 4x=5y-5 10y=10-8x

*February 16, 2013*

**physicis**

a 0.30 kg mass attached to a spring is pulled back horizontally across a table so that the potential energy of the system is increased from zero to 120 J. Ignoring friction what is the kinetic energy of the system after the mass is released and has moved to a point where the ...

*February 15, 2013*

**Physics**

At the low point in its swing, a pendulum bob with a mass of 0.2 kg has a velocity of 4 m/s What is the Kinetic at the low point? and Ignoring air resistance how high will the bob swing above the low point before reversing direction?

*February 15, 2013*

**pre algerbra**

Please solve the system with the elimination method. Explain each step as it is performed. 5y = x 2x - 3y = 7

*February 13, 2013*

**Algebra**

On a 30 day calendar which begins on a Wednesday and ends on a Thursday, what is the probability in a random drawing that the date would be a Monday?

*February 12, 2013*

**math**

sally has a bag of mixed lollies.The bag contains toffees,mints,fruit drops,smarties,jelly beans,candies and licorice.Sally allows every one in her class to choose 3 lollies,but they must not choose more than one of each kind.How many different combinations of lollies are

*February 10, 2013*

**Algebra**

I actually had -10, forgot to put it above. Thank you. I had stopped at the 44 x 10^-10 and didn't go one step further. Thanks again Reiny.

*February 6, 2013*

**Algebra**

scientific notation for (5.5*10^-8)(8*10^-2) I got (5.5*8)(10^-8*10^-2) then 44*10^10 What am I doing wrong?

*February 6, 2013*

**College Algebra**

cubic root of 27x^4 y^13

*February 6, 2013*

**algebra**

how do you solve 2w^9(5w)(4w^10)

*February 4, 2013*

**Algebra**

how do you simplify kz(k+1/z)

*February 4, 2013*

**algebra**

how to solve the formula for the indicated letter for x= w + y + z/4 for y

*February 2, 2013*

**chemistry**

determine the quantity of heat needed to convert 17.0g of solid mercury at -50.0C to mercury vapor at 25C . Specific heats: , 24.3C , , 28.0C . Melting point of hg, -38.87C . Heat of fusion, 2.33 .

*January 30, 2013*

**math**

Consider the experiment of choosing the top 7 cards from a shuﬄed deck in two ways: (a) Without replacement. 1. What is the sample space? 2. What is the probability that you get only red cards? (b) With replacement. 1. What is the sample space? What is the probability ...

*January 27, 2013*

**algebra**

Thanks ;)

*January 24, 2013*

**algebra**

Chase scored 14 points on Monday, and he doubled his score each day thereafter. How many points did he score on Thursday? A. 224 points B. 112 points C. 56 points D. 42 points Thanks :)

*January 24, 2013*

**Spanish (Please Help)**

Not always, I'm here today because I need some help on Algebra.

*January 24, 2013*

**Spanish (Please Help)**

100% Sure :)

*January 24, 2013*

**Spanish (Please Help)**

4) C. 5) B. Good Luck ;)

*January 24, 2013*

**Spanish (Please Help)**

Ok.. I'm hispanic so I'm going to help you. 1) Hago 2) Hacen 3) Hacemos

*January 24, 2013*

**statistics**

Using the fitted regression model, estimate the average change in cry time for infants with severe pain versus those without severe pain, holding group constant. Provide a 95% confidence interval for this estimate. My question: What holding group constant means?

*January 19, 2013*

**statistics**

Using the fitted regression model, estimate the average change in cry time for infants with severe pain versus those without severe pain, holding group constant. Provide a 95% confidence interval for this estimate

*January 19, 2013*

**fundamentals of math**

thanks. its been a long time for math.

*January 17, 2013*

**fundamentals of math**

if 3 is added to a number and this sum is doubled, the result is two more than the number. Find the number.

*January 17, 2013*

**maths**

integrate by parts integrate (4+x^2)^1/2

*December 29, 2012*

**english**

has anyone read the women in black???? chapter two-a london particular i need to compare the atmosphere at the begging of chapter one to chapter two and the quote is "it was monday afternoon in november and already growing dark

*December 27, 2012*

**maths**

Express sin 2x cos 4x as a sum of trigonometric functions.

*December 23, 2012*

**algebra URGENT!**

Solve the system using elimination. 2x – 2y = –8 x + 2y = –1 And this one: Solve the system using elimination. 3x – y = 28 3x + y = 14 Pleease help me :(

*December 21, 2012*

**I NEED HELP!.. Algebra**

Find a solution to the following system of equations. -5x + y = -5 -4x + 2y = 2

*December 21, 2012*

**algebra**

Hey, I don't undertand how to solve this equation using substitution. 3y = -1/2x + 2 y= x + 9

*December 21, 2012*

**algebra**

The sum of two numbers is 82. Their difference is 24. Choose the system of equations that describes this situation. Solve by elimination to find the two numbers.

*December 21, 2012*

**algebra**

Thanks, now i got it :)

*December 21, 2012*

**algebra**

I still trying to do it, but it is hard for me, can you explain that again? Thanks Ms. Sue.

*December 21, 2012*

**algebra**

Solve the system of equations using substitution. y = x + 6 y = –2x – 3

*December 21, 2012*

**algebra**

Solve the system of equations using substitution. y = 2x – 10 y = 4x – 8

*December 21, 2012*

**algebra**

Identify the graph of the pair of equations as parallel, intersecting, or identical. y = 5x – 4 y = 5x – 5

*December 21, 2012*

**algebra**

Does the system of equations have no solution, one solution, or infinitely many solutions? y = 2x – 3 y = –x + 3

*December 21, 2012*

**algebra**

Does the system of equations have no solution, one solution, or infinitely many solutions? y = x + 4 y – 4 = x

*December 21, 2012*

**algebra**

Which graph represents the following system of equations? y = 3x + 3 y = –x – 3

*December 21, 2012*

**7th grade science**

sperm

*December 12, 2012*

**Physics**

When a metal pipe is cut into two pieces, the lowest resonance frequency in one piece is 244Hz and that for the other is 454Hz. What resonant frequency would have been produced by the original length of pipe? (Assume the speed of sound in air is 345 m/s) ^ I already got the ...

*December 2, 2012*

**Chemistry**

Suppose I put 1 billion bacteria in a 10 ml tube of saline, mix well, and label this tube A. Answer the following questions: 1. Take 1 ml from tube A and put it in an empty tube B. What is the concentration and number of bacteria in tube B?

*November 27, 2012*

**Chemistry**

Suppose I put 1 billion bacteria in a 10 ml tube of saline, mix well, and label this tube A. Answer the following questions: 1. Take 1 ml from tube A and put it in an empty tube B. What is the concentration and number of bacteria in tube B?

*November 27, 2012*

**world history**

Which of the following was not an innovation that came about due to militarization in the 1800s?

*November 27, 2012*

**MATHS**

how can you explain the steps and formula

*November 20, 2012*

**MATHS**

Differntiate sin(sinx) using the product rule

*November 20, 2012*

**Math**

Solve the equation: 125^r=5

*November 14, 2012*

**Math**

What is the inverse equation of f(x)=(x+2)/(x-1)?

*November 14, 2012*

**Intergated chemistry/physics**

Draw a setup containing 3 gears. For every turn of the input gear, you need the output gear to spin 9 times. The drawing doesn't have to be perfect, but make sure to label the input gear, the output gear, and the number of teeth on each gear. Please E-mail me the picture ...

*October 31, 2012*

**physics**

A 80 kg object slides at a 20 degree plane downward at 5m/s. An object 2 collides with object 1 by falling from 7 meter height and they stick together. Final speed of objects? I know the speeds would be the same. Would momentum equation work to solve this? The perfect ...

*October 25, 2012*

**science**

what are some interactions that can take place when a beam of light hits a glass tank and then enters the water

*October 24, 2012*

**stats**

Suppose a shipment of 500 machine parts contains 62 defective and 438 non-defective machine parts. From the shipment you take a random sample of 25. You are interested in the number of defective machine parts out of 25 trials and corresponding probabilities. When sampling with...

*October 21, 2012*

**Calculus 2**

how do I find the fluid force of a vertical semicircle that has been divided into three equal sectors of 60 degrees each. I know what the equation to find the fluid force for the whole semicircle is. but how do I find L(y) for each semicircle.

*October 11, 2012*

**Intergated chemistry/physics**

You are riding a 30 pound bicycle and you weigh 150 pounds. You are travelling at 20 miles per hour and fail to notice the 30 pound dog is in your path. If you transfer half of your momentum to this dog, what speed could he potentially reach?

*October 4, 2012*

**Intergated chemistry/physics**

Your teacher bumps into you in the hallway and knocks you down. After he apologizes, he asks you to figure out how fast he was going. By some magical coincidence, you just happened to be wearing a gauge that measured your mass to be 75 kilograms and your speed to be 25 miles ...

*October 4, 2012*

**Intergated chemistry/physics**

A 200 pound go-kart with a speed of 20 miles/hour collides with a 2nd go-kart (that was at rest) and causes it to move at a speed of 15 miles per hour. What is the mass of the 2nd cart if the first kart came to a stop upon collision?

*October 4, 2012*

**Intergated chemistry/physics**

A 10 pound bowling ball with a speed of 2.0 meters/second hits a 6 pound bowling ball. If the 10 pound bowling ball stops after the collision, what is the resulting speed of the 2nd ball in meters/second

*October 4, 2012*

**Intergated chemistry/physics**

A 200 man is running 3 miles per hour and collides with a 125 pound man. If the larger man transfers all of his momentum to the smaller man, will the smaller man travel slower, faster or at the same speed as the larger man?

*October 4, 2012*

**Intergated chemistry/physics**

What is the speed (in m/s) of an object that has a mass of 2.5 kilogram and a momentum of 1,000 kg m/s?

*October 4, 2012*

**Intergated chemistry/physics**

If a bowling ball is rolling at a speed of 1.5 meters/second and has a momentum of 10.0 kg m/s, what is the mass of the ball in kilograms?

*October 4, 2012*

**Intergated chemistry/physics**

Which has more momentum: a 45 gram golf ball travelling at 180 miles per hour or a 430 gram soccer ball travelling at 20 miles per hour?

*October 4, 2012*

**Intergated chemistry/physics**

What is the momentum of a 100 kilogram football player moving with a speed of 3.5 meters/second. The units should be written as kg m/s.

*October 4, 2012*

**Intergated chemistry/physics**

If you were in a car traveling 50 miles/hours, how many miles could you travel if you continued for 15 hours without stopping?

*October 3, 2012*

**Intergated chemistry/physics**

If you were in a car travelling at 50 miles/hour, how many hours would it take to get to Miami, FL from Evansville, IN? Assume that there is no stopping on the way. Miami is 1,060 miles from Evansville.

*October 3, 2012*

**Intergated chemistry/physics**

If the elevator were falling on the moon 9800 meters/second^2, what would the force be? (hint: you will need to look up the acceleration due to gravity on the moon.)

*October 3, 2012*

**Intergated chemistry/physics**

The Lamborghini Diablo sports car can accelerate from 0 kilometers/hour to 99.2 kilometers/hour in 4.0 seconds. What is the acceleration of this car in kilometers/hour^2. (hint: you must convert 4.0 seconds before putting it into the equation.)

*October 3, 2012*

**Intergated chemistry/physics**

A car is accelerated at a rate of 2.5 meters/second^2. If the starting speed is 5.0 meters/second, how many seconds will it take the car to reach a final speed of 27.0 meters/second?

*October 3, 2012*

**Intergated chemistry/physics**

A parachute on a dragster racing-car opens and changes the speed of a car from 85 meters/second to 45 meters/second. Of this car is decelerating (slowing down) at a rate of -8.9 meters/ second, how many seconds will this take?

*October 3, 2012*

**Physics**

A boat, having an initial velocity of 6.6m/s east undergoes an average acceleration of 2.2 m/s squared south for 2.5 s. Determine final velocity after the time interval (magnitute and direction)

*September 30, 2012*

**AP physics**

A particle moving uniformly along the x axis is located at 17.9 m at 1.45 s and at 3.9 m at 2.7 s. Find its displacement during this time in- terval. Answer in units of m What is the average velocity speed during this time interval. Answer in units of m/s

*September 30, 2012*

**Calculus 2**

Calculus. Mary designed a new viewing window consisting of a rectangle and a semi circle for a fresh water aquarium. The window is as follows and the top is located 10 feet below the water's surface. How much force is on the window?

*September 27, 2012*

**Calculus 2**

Calculus 2. Tom and Mike have a bet as to who will do the most work today. Mike has to compress a coil 200 feet. It takes Mike 250 lbs to compress the coil 10 feet. Tom needs to pump water through the top of a cylindrical tank sitting on the ground. The tank is half full, has ...

*September 27, 2012*

**Calculus 2**

Calculus work problem. John bought the following corner lot. Two sides are bounded by 2 roads the back is bounded by a stream that follows the curve y = -x^3 + 8. He wants to build a house in the center of the lot. Where will that be? Please show all work

*September 27, 2012*

**maths**

Daniel has a rabbit, a ferret, a gerbil, and a turtle. He feeds them in a different order each day. in how many different orders can Kelvin feed his pets?

*September 26, 2012*

**math**

jade and isis are designing a soccer uniform they want use two colors on the shirt, their choices are green , orange, yellow, purple, blue silver. how many ways can they choose two colors?

*September 26, 2012*

**Math**

A function that represents the volume of a cardboard box is V(x) = -0.65x^3 + 4x^2 + 3x, where x is the width of the box. Determine the width that will maximize the volume. What are the restrictions on the width? The answer is 4.45 and domain is 0<x<6.83

*September 25, 2012*

**Advanced Functions**

Two soccer players start at opposite sides of an 80-m field. One runs at 4 m/s and the other runs at 5 m/s. If they run back and forth for 15 mins, how many times will they pass each other? **The answer is 25 but I keep getting 45!!

*September 25, 2012*

**physics 101**

A person in an elevator is holding a 15 kg block by a cord rated to withstand a tension of 180 N. When the elevator starts up, the cord breaks. What was the magnitude of the minimum acceleration of the elevator?

*September 22, 2012*

**Physics**

A person climbs from a Paris metro station to the street level by walking up a stalled escalator in 96.5 s. It takes 60.0 s to ride the same distance when standing on the escalator when it is operating normally. How long would it take for him to climb from the station to the ...

*September 21, 2012*

**Physics**

A ball is thrown from a point 1.38 m above the ground. The initial velocity is 19.9 m/s at an angle of 33.8° above the horizontal. Find the maximum height of the ball above the ground. Calculate the speed of the ball at the highest point in the trajectory.

*September 21, 2012*

**Science**

pH of: 2.50mL of 0.100M nitric acid added to 30mL of 0.200M potassium hydroxide Please show me working out :)

*September 20, 2012*

**Business Law**

Unconstitutiabal

*September 17, 2012*

**Algebra**

What is the square root of -25? Can you please write out the steps of finding it?

*September 13, 2012*