Monday

April 27, 2015

April 27, 2015

Total # Posts: 194

**Physics**

You attach one end of a spring with a force constant k = 893 N/m to a wall and the other end to a mass m = 2.02 kg and set the mass-spring system into oscillation on a horizontal frictionless surface as shown in the figure. To put the system into oscillation, you pull the ...
*April 22, 2015*

**Chemistry**

In a solution of a weak acid and its conjugate base, which condition has to be true for pH to equal pKa? The concentration of acid has to be greater than the concentration of base. The concentration of acid has to be equal to the concentration of base. An indicator has to be ...
*April 20, 2015*

**Chemistry**

Calculate the hydronium ion concentration of blood which has a pH of 7.24. 7.17 x 10-4 M 5.75 x 10-8 M 1.15 x 10-7 M 0.86 M none of the above I had chose 1.15*10^-7 by doing the log equation -log(1.15...) and I but it goether with -log(10*^-7.24) and it was closest to 14 and ...
*April 20, 2015*

**Chemistry**

What is the pH of a solution which has hydroxide concentration, [OH-], equal to 7.6 x 10-4 M? 0.88 3.12 10.9 13.1 none of the above I had chose 3.12 for this one and this one was also wrong. I did this because I did the equation -log(7.6*10^-4) and got 3.12.
*April 20, 2015*

**Chemistry**

How many moles of chlorine are there in 16.0 mL of 0.450 M CaCl2? 0.0072 mol 0.0144 mol 0.0216 mol 0.0375 mol none of the above I had chose 0.0072 and had submitted it in my assignment, but it had said it was wrong. I chose 0.0072 because I did this equation: 16/ 1000*0.450 ...
*April 20, 2015*

**Chemistry**

I took it as 4.9 x 10^-10 was correct from what you said and when I chose that as an answer it said it was wrong?
*April 20, 2015*

**Chemistry**

Four sets of conjugate acid/base pairs and Ka of the acid are given. Which pair would be the best to form a buffer at pH = 9.2? You can use the Henderson-Hasselbalch equation to answer this question. HCNO/CNO- 3.5 x 10-4 HC2O4-/C2O4- 5.1 x 10-5 H2CO3/HCO3- 4.3 x 10-7 HCN/CN- 4...
*April 20, 2015*

**Chemistry**

The Ka for the reaction of acetic acid and water is 1.8 x 10-5. Which of the following statements is true at pH 7? A.) there is much more acetic acid than acetate ion B.) there is more acetate ion than acetic acid C.) the concentration of acetate ion is equal to that of acetic...
*April 6, 2015*

**Chemistry**

The ethylammonium ion, CH3CH2NH3+, has a pKa of 10.81. It reacts with water to form ethylamine, CH3CH2NH2 and H3O+. Which of the following statements is true at pH 7? A.) ethylamine predominates B.) ethylammonium ion predominates C.) the pH is higher than pKa of the ...
*April 6, 2015*

**physics**

A 0.205 kg bird flying along at 7.8 m/s sees a 0.029 kg insect heading straight toward it with a speed of 15 m/s (as measured by an observer on the ground, not by the bird). The bird opens its mouth wide and enjoys a nice lunch. What is the bird's speed immediately after ...
*March 30, 2015*

**Statistics and Probability**

Mallory has a credit score of 680 and she is offered and interest rate of 8.3%. is this a good offer? Explain your answer.
*December 8, 2014*

**Algerbra math**

(7x^2+3x+9)+(2x^2+5x-2)
*October 1, 2014*

**Calculus**

2x -------- (x-2)(x+2) using partial fractions That's supposed to be a division sign of some sort
*May 22, 2014*

**Calculus**

WHat?
*May 21, 2014*

**Calculus**

find the co-ordinates y=x(2-x) where the gradient is 2
*May 21, 2014*

**Calculus**

Where did -h come from
*May 21, 2014*

**Calculus**

1/X by first principles
*May 21, 2014*

**Calculus**

A fragment of bone is discovered to contain 20% of the usual carbon-14 concentration. Estimate the age of the bone to the nearest hundred years, given that Carbon-1 is radioactive with half-life of 5730 years and the rate of decay is given by the following differential ...
*May 21, 2014*

**Calculus**

What do you mean my discs and shells?
*May 21, 2014*

**Calculus**

Find the volume of the solid generated by rotating about the y axis the area in the first quadrant bounded by the following curve and lines. y=x^2, x=0, y=2.
*May 21, 2014*

**Survey Math help**

A movie complex has eight different movie theaters. The manager of the complex wants to conduct a survey to determine which snacks to add to the menu. Which represents the best sample the manager could use for the survey? Would I do specific ages the first 100 randomly picked ...
*May 1, 2014*

**Coordinates Math"Steve"**

Is the proportional? x: 1 3 4 6 y: -4 -12 -16 -24 I think it is. Am I correct?
*April 25, 2014*

**Geometery help**

Ok I will thanks guys.
*April 25, 2014*

**Geometery help"Steve"**

The point Q(x,y) is reflected in the origin. Use arrow notation to describe the original point and its reflection. I chose this: (x,y) to (x,y) Am I right?
*April 25, 2014*

**Help me solve??**

Thank you for the steps that helps so much/. Thank you Steve!
*April 25, 2014*

**Help me solve??**

XYZ has vertices X(5,6), Y(9,12), and Z(12,8). it is translated right 8 units and up 3 units. What are the coordinates of X', Y', and Z' ?
*April 25, 2014*

**Math**

If you put me into 7 equal groups with 3 in each group and 5 are left over, what number am I?
*March 6, 2014*

**what??**

im not trying to fool anything this is not a name change.MS.SUE Im not trying to be disrecptful since you do help a lot of kids but I also have talking to a lot of kids to and they say that sometimes your very rude and mean....im just trying the help the guy @mathhelp123 he ...
*January 8, 2014*

**math**

he will help you mathhelp
*January 8, 2014*

**math**

I don understand this either
*January 8, 2014*

**math**

I just saw this guy post this here and I think he needs help??? A recipe calls for 4 pounds of fruit.you have 60 ounces of fruit. A.do you have as much fruit as you need? B.if not,how much more do you need?
*January 8, 2014*

**history**

trouser wearing members of a revolutionary uprising of the french working class were called the___________?
*November 29, 2013*

**history**

the ____ act required king______ 1 to convene parliament every three years. is it parliament,king charles?
*November 29, 2013*

**PHYSICS**

Two 75 kg hockey players skating at 5.50 m per s collide and stick together. if the angle between their initial directions was 120 degress, what is their velocity after the collision?
*November 5, 2013*

**Chemistry**

Anhydrous aluminum oxide can be reduced to aluminum according to thisa chemical equation: 2 Al2O3 (s) ---> 4 Al (l) + 3 O2 (g) Calculate the mass of aluminum oxide reacted if 82 g of Al was produced and the percent yield was found to be 89.3%
*October 18, 2013*

**Chemistry**

What mass of copper(II) nitrate would be produced from the complete reaction of 65.3 g of copper, according to the chemical reaction shown below? Cu + 2 AgNO3 ----> Cu(NO3)2 + 2 Ag Use the masses to two decimal places using the periodic chart in the front of your text. ...
*October 18, 2013*

**chemistry**

a. How many atoms of hydrogen are in 25.0 g of ammonia (NH3)? Use the format 6.02E+23 for 6.02 x 1023 b. How many atoms of nitrogen are in the same amount of ammonia? Use the molar mass to two decimal places found on the periodic table in the front of your text.
*October 18, 2013*

**calculus**

Meg's pension plan is an annuity with a guaranteed return of 4% per year (compounded quarterly). She would like to retire with a pension of $20,000 per quarter for 10 years. If she works 30 years before retiring, how much money must she and her employer deposit each quarter?
*September 16, 2013*

**Chem**

Caculate the volume of CO2 gas given off at 756 mm Hg and 23C when 150 kg of limestone(CaCO3) is heated until it decomposes according to the following reaction:CaCO3(s)=CaO(s)+CO2(g)
*March 13, 2013*

**science**

Which of the following is true about an object that floats in water? (1 point) The object is less dense than frozen water. The mass of the object is less than that of water. The density of the object is less than that of water. The volume of the water is greater than the ...
*March 1, 2013*

**Physics**

The focal length of the objective of a telescope is 0.2 m and the eyepiece has a focal length of 1.6 m. What is the length of the telescope? A. 1.8 m B. 1.4 m C. 1.6 m D. .90 m E. 8.0 m
*January 20, 2013*

**english**

Please help me write an essay. the question is "What do you think the theme is of Our Town and how is it shown?"
*January 6, 2013*

**Math word problem **

Patsy has cheerleading practice on every fourth school day. She wants to be in the school play, but they have practice on every sixth school day. If both started on September 5th, what would be the first date that she has to choose between cheerleading and play practice? I ...
*December 5, 2012*

**Math help!**

I got the same thing 3. our teacher we thought said to subtract the two middle and then divide it by two to get the median. We are confused.
*October 10, 2012*

**Math help!**

Mean 82 Median 3 Mode 81 The median? But I really do not understand it because it is such a low number? I am sorry I am trying to understand.
*October 10, 2012*

**Math help!**

It would have to be the median?
*October 10, 2012*

**Math help!**

The mean?
*October 10, 2012*

**Math help!**

Jack has the following scores on exams in his math class. 81, 87, 93, 89, 61, 81 If he wants to make his performance sound as good as possible, which measure should he use—the mean, the median, or the mode of his exam grades when he talks about how he is doing?
*October 10, 2012*

**Math**

oops! yes I forgot to divide by two! 19 is the median. And would that best represent the ages?
*October 10, 2012*

**Math**

so the mean is 16.75 The median is 12 right? Because I had to subtract the two middle numbers to get the middle number. The mode is 2 So would it be the median to represent the ages of the houses?
*October 10, 2012*

**physics**

The upward force is the same in both situations.
*September 29, 2012*

**statistics**

The average temperature in households is 67.6 degrees F. The standard deviation is 4.2 degrees F. A random sample of 51 households is to be selected What is the probability that the average of this sample will be within 1.4 STANDARD ERRORS of the population mean?
*September 28, 2012*

**english**

a good thesis statement on why teachers should have the authority to remove disruptive students from their classes permanently.
*September 28, 2012*

**History**

How did england change after its war with spain? and How did this change played a role and part in history by analyzing the magnitude and scope?
*September 23, 2012*

**science**

A conatiner filled with marbles weighs 435 grams. The container weighs 28 grams. What is the mass of the marbles?
*September 18, 2012*

**education**

I just need to know the steps required for a multicultural education to be effective
*September 16, 2012*

**education**

Read the following scenario: You are a second-grade teacher at Happy Valley Elementary School. You are teaching language arts and social studies. Your classroom of 21 students consists of 7 white students, 5 Latino students, 4 African American students, 3 Native American ...
*September 16, 2012*

**Economics**

2. If a firm increases all of its inputs by 60 percent and its output increases by 90 percent, then you know that: A) it is encountering diseconomies of scale. B) it is encountering economies of scale. C) it is encountering constant returns to scale. D) the marginal products ...
*September 13, 2012*

**Economics**

Suppose that a tour bus business incurred implicit costs of $600,000 and explicit costs of $7 million in a specific year. If the firm sold 125,000 tours at $60 per person, its accounting: A) profits were $100,000 and its economic profits were $500,000. B) losses were $100,000 ...
*September 13, 2012*

**Chemistry**

A rock sample contains only Sb2S3 and FeS. If 835g of the sample contains 11.2% antimony, what is the mass percent of the Sb2S3 in the sample? What is the mass percent of the sulfur in the sample? So far, I have determined that 11.2% of an 835g sample is 93.52g Sb, the molar ...
*August 31, 2012*

**Chemistry**

100 ml of 0.01N HCl is added to 0.9L of distilled water. What would the final pH of the solution be?
*August 30, 2012*

**Introduction to HS**

Ok, thank you very much for your help!!
*July 25, 2012*

**Introduction to HS**

I am having trouble with a question. In order to get an idea of significant subject areas in a chapter, it is best to read the. A. Subheads B. Graphics C. Captions D. Table of contents In my study guide it states : Read all the subheadings and sub-subheadings. These will give ...
*July 25, 2012*

**business stat **

1. Suppose quality control inspectors at the coffee house chain take a sample of 100 pieces of this chocolate product from an incoming shipment. They find a sample average of 60% cacao with a standard deviation of 8%. What is the standard error of the sampling distribution of ...
*July 23, 2012*

**Chemistry**

If you reclaim 0.250g Ag from AgNO3, how much AgNO3 did you have to begin with?
*July 16, 2012*

**Physics **

A 3.30-kN piano is lifted by three workers at a constant speed to an apartment 28.8 m above the street using a pulley system fastened to the roof of the building. Each worker is able to deliver 197 W of power, and the pulley system is 75.0% efficient (so that 25.0% of the ...
*June 17, 2012*

**Physics**

If a projectile is launched from Earth with a speed equal to the escape speed, how high above the Earth's surface is it when its speed is three-fifths the escape speed? I keep getting the answer 2.56x10^6 m after solving it a few different ways. Help would be great.
*April 28, 2012*

**geometry**

Factor 15x^2 - 8x - 16
*March 8, 2012*

**algebra 2/math**

how do i factor x^3+2x^2-x-2
*February 29, 2012*

**algebra**

X^2-4x=0
*February 21, 2012*

**chemistry**

design a simple lever that could be raised and lowered smoothly using niitinol wires.
*February 16, 2012*

**Physics**

A driver in a car traveling at a speed of 56.0 mi/h sees a deer 116 m away on the road. Calculate the minimum constant acceleration that is necessary for the car to stop without hitting the deer (assuming that the deer does not move in the meantime).
*February 2, 2012*

**AP Chemistry**

This is part of a marathon problem, we have to identify the five compunds of H, N, and O described below. For each compound, I have to write a Lewis structure that is consistent with the information given. a.) All the compunds are electrolytes, although not all of them are ...
*December 4, 2011*

**Physics.**

What is the transfer mechanism of energy, momentum, and angular momentum?
*November 27, 2011*

**Physics help please**

gets larger?
*November 27, 2011*

**Physics help please**

suppose you have 2 cars, and the larger one is twice as massive as the smaller one. If you and a friend push on them so that their accelerations are equal, how must the forces applied to the cars compare? a. the force on the larger car is equal to that on the smaller car. b. ...
*November 27, 2011*

**algebra**

Suppose D=(w+2)(w-3)(w+6).For what three values of w will D have a value of 0?
*November 21, 2011*

**Chemistry **

If solution A had a pH of 8, and solution B had 1,000 times this hydrogen ion concentration what would be the pH of solution B, and would solution B be acidic or basic?
*November 14, 2011*

**trig**

find the coordinates of the terminal point on the unit circle determined by t=9pt/7 to two decimal places
*November 13, 2011*

**Physics**

The position vector r of a particle moving in an xy plane is given by [r = (6t^3-3t)i + (4-1t^4)j] with r in meters and t in seconds. What is the angle between the positive direction of the x axis and a line tangent to the particle's path at t = 3 s? Give your answer in ...
*September 25, 2011*

**Math**

To subtract 91 from 99, do you need to regroup? Explain
*September 19, 2011*

**Math**

To subtract 91 from 99, do you need to regroup? Explain
*September 19, 2011*

**3rd math**

Bethany has 40 apples. Write a subtraction story about the apples that would require regrouping. Then write the answer in a complete sentence.
*September 19, 2011*

**physics**

a rocket blasts off and moves up with an acceleration of 12 m/s2 until it reaches 30 m then the engine shuts down and the rocket continues in free fall. What is the max hieght of the rocket and what is the total duration of the rockets flight?
*August 31, 2011*

**chemistry**

When 0.100 mol of carbon is burned in a close vessel with 8.00g of oxygen, how many grams of carbon dioxide can form?
*July 24, 2011*

**grammar**

A Superblade was used at the 2 o'clock position, and the anterior chamber was entered was used is a verb ,was entered is also a verb ,am i right
*June 15, 2011*

**Thermodynamics**

An intrepid explorer takes 400 g of ice from the cold Siberian environment, where the temperature is –40 degrees and places it in a kettle inside his mobile laboratory. The ice melts and he heats the water to +40 degrees. What is the total amount of heat absorbed by the ...
*June 6, 2011*

**algebra**

simplify and write using only positive exponents. thanks. (2x^3y^4)^-2 divided by (8xy^6)^-3
*May 25, 2011*

**Chemistry**

write the balanced equation for the ionization of the weak base pyridine, C5H5N, in water
*May 8, 2011*

**chemistry dilutions**

you have 47 mL of a 2 M stock solution that must be diluted to .5 M how much water should you add
*May 5, 2011*

**calculus**

The function f is continuous on the closed interval [0,6] and has values that are given in the table below. x |0|2|4|6 f(x)|4|K|8|12 The trapezoidal approximation for(the integral): 6 S f(x) dx 1 found with 3 subintervals of equal length is 52. What is the value of K? How do ...
*May 2, 2011*

**Chem 100**

at 1 atm how much energy is required to heat 67 grams of H2O(s) at -22 degrees C to H2O(g) at 159 degrees C
*May 1, 2011*

**Math**

50=n/2+26
*April 11, 2011*

**4th grade math**

Find a rule that gives the third number from the first two numbers. Fill in the blanks.....10, 4, 5, ? 15, 7,7, ? 19,9,?
*March 17, 2011*

**Chemistry**

I don't understand how you know what state designation things are in a chemical equation. For example this is given: 2 (NH4)3PO4 (__) + 3 Ba(NO3)2 ---> Ba3(PO4)2 (__) + 6 NH4NO3 (__) How do you just know what to put for their state or phase designation?
*March 10, 2011*

**reimbursement methodologies**

does anyone have answers to test 38181803 for penn foster
*February 19, 2011*

**Physics**

A coiled Hookean spring is stretched 10 cm when a 1.5kg mass is hung from it. Suppose a 4 kg mass hangs from the spring and is set into vibration with an amplitude of 12 cm. A. Find the force constant of the spring. B. Find the Maximum restoring force acting on the vibrating ...
*February 16, 2011*

**algebra**

-9 + 36 divided by 6 times 2 -(-6) - 5 +2 = ? I'm having trouble with the order of operations.
*February 15, 2011*

**Math**

estimate:42.9*7.84=
*February 9, 2011*

**math**

An urn holds 13 identical balls except that 2 are white, 4 are black, and 7 are red. An experiment consists of selecting two balls in succession without replacement and observing the color of each of the balls. How many outcomes are in the sample space for this experiment? How...
*February 2, 2011*