# Posts by Sar

Total # Posts: 36

**Algebra II**

h=1+13t-5t²

*April 10, 2014*

**geometrey**

a chord of 42 cm with the distance of 5 cm from center of the circle find the raduis of the circle?/.

*April 6, 2014*

**geometrey**

whats a circle?

*April 6, 2014*

**physics**

two masses are in the ratio 1:2 are thrown vertically up with the same speed . what is the effect on time by the mass?

*September 17, 2012*

**math:solving for an exponent.**

Bob, thank you. I thought I was going insane there for a minute. I guess the professor made a mistake. We are all human (but it drives me crazy when I'm trying to study haha)

*October 4, 2011*

**math:solving for an exponent.**

No. The math he did was handwritten. I guess he must have made a mistake because this is driving me nuts. Everything listed in my post is CORRECTLY copied from the piece of paper I got it on.

*October 4, 2011*

**math:solving for an exponent.**

I can't get the right answer, where am I going wrong? 7.0x10^9= (6.7x10^9)(2.72^r*3) 1.04 = 2.72^r*3 When I solve for this, I get ln (1.40) = 0.03922 then 0.03922 / 3 = 0.0130 So my r equals 0.0130 BUT the teacher says the answer is 0.05 = r *3 0.02 = r What did I do wrong...

*October 4, 2011*

**history**

The causes of Sand Creek massacre were rooted in the decades-long conflict for control of the Great Plains of eastern Colorado. The Fort Laramie Treaty of 1851 guaranteed ownership of the area north of the Arkansas River to the Nebraska border to the Cheyenne and Arapahoe. By ...

*November 12, 2010*

**Physics: Angular Width. Why is my answer wrong?**

Well, that was a step my teacher did so I just followed it. However, .00082 degrees is not the correct answer either (or the variant of 8.2e-4). So I am just totally lost on this one. :/

*November 12, 2010*

**Physics: Angular Width. Why is my answer wrong?**

A beam of yellow laser light (590 nm) passes through a circular aperture of diameter 5.0 mm. What is the angular width of the central diffraction maximum formed on a screen? I can't seem to get this answer right. I don't think I am finding the first part of the problem...

*November 12, 2010*

**Physics: Angular Width. Why is my answer wrong?**

I have also tried using the positive of the angular width. But that is wrong, too. I used the same equation as i did above but with the 1.22

*November 9, 2010*

**Physics: Angular Width. Why is my answer wrong?**

I just tried the problem with 1.22 and i got -1.21 as my final angular width. However, this is also incorrect. any ideas where I am going wrong?

*November 9, 2010*

**Physics: Angular Width. Why is my answer wrong?**

A beam of yellow laser light (590 nm) passes through a circular aperture of diameter 5.0 mm. What is the angular width of the central diffraction maximum formed on a screen? I can't seem to get this answer right. I don't think I am finding the first part of the problem...

*November 9, 2010*

**Physics: Focal length why is my answer wrong?**

Actually, those answers are incorrect.

*October 28, 2010*

**Physics: Focal length why is my answer wrong?**

An old refracting telescope in a museum is 44.0 cm long and the caption states that the telescope magnifies images by a factor of 29.0. Assuming these numbers are for viewing an object an infinite distance away with minimum eyestrain, what is the focal length of each of the ...

*October 28, 2010*

**Physics**

A uniform magnetic field points north; its magnitude is 3.5 T. A proton with kinetic energy 6.0 × 10-13 J is moving vertically downward in this field. What is the magnetic force acting on it? This is what I've done. The answer is incorrect. Please help me find out ...

*September 22, 2010*

**Magnetic Field Forces: Physics**

A uniform magnetic field points north; its magnitude is 3.5 T. A proton with kinetic energy 6.0 × 10-13 J is moving vertically downward in this field. What is the magnetic force acting on it? This is what I've done. The answer is incorrect. Please help me find out ...

*September 22, 2010*

**Second order half life**

You are most correct, I did not. Thank you so much.

*September 21, 2010*

**Second order half life**

At 100 degrees C , a certain substance undergoes second-order decomposition with a half-life of 26 minutes. If the initial concentration of the substance is 3.9×10−2M , what is the value of the rate constant at 100degrees C? So I put in (1560seconds) 1/2 = 1/ k (3....

*September 21, 2010*

**Physics: Diameter of a nichrome wire**

2.27mm is the new answer I got, which is correct. Thanks for pointing that out, Bob. I was going insane trying to figure this out.

*September 9, 2010*

**Physics: Diameter of a nichrome wire**

Ooo. Gosh, I must have just been looking at the wrong number or something. I feel silly now.

*September 9, 2010*

**Physics: Diameter of a nichrome wire**

If 49 m of nichrome wire is to have a resistance of 13.0 ohms at 20°C, what diameter wire should be used? I've done this: (108e-8)(49)/10.0 ohms = 5.29e-6m^2 Then 5.29e-6m^2/pi then r = sqrt(1.68e-6m^2) and got .00129 = 1.29e-3 1.29mm r=2(1.29mm) = 2.58mm But this is ...

*September 9, 2010*

**finding boiling points of solutions**

What is the boiling point (in degrees Celsius ) of each of the solutions below? For water, Kb = 0.51 (Degrees C * kg)/mol The vapor pressure of water at 45.0C is 71.93 mm Hg. 1. A solution of 15.0g of urea, CH4N2O, in 164 g of water at 45.0 degrees C. For this one, I've ...

*September 9, 2010*

**Mole fractions in a liquid mixture:**

When I did that I got this: 2.6 for acetone mole fraction 1.4 for ethyl acetate mole fraction 119 acetate vapor 30 ethyl acetate vapor None of those answers were correct. :[

*September 2, 2010*

**Mole fractions in a liquid mixture:**

Acetone, C3H6O, and ethyl acetate, C4H8O2, are organic liquids often used as solvents. At 30 degrees C, the vapor pressure of acetone is 285 mm Hg and the vapor pressure of ethyl acetate is 118mm Hg. the solution is prepared at 30 degrees C by dissolving 27.0 g of acetone in ...

*September 2, 2010*

**Mole fraction of a vapor pressure?**

I see where i went wrong. I was trying to take the mole fraction (.405) and divide it into the 176. Thank you.

*September 2, 2010*

**Mole fraction of a vapor pressure?**

If 0.380 mol of a nonvolatile nonelectrolyte are dissolved in 3.00 mol of water, what is the vapor pressure P(H2O) of the resulting solution? The vapor pressure of pure water is 23.8 torr at 25 C. I got this answer correct: 21.1 torr A solution is composed of 1.50mol ...

*September 2, 2010*

**Chemistry: Raoult's Law**

i got the mole fraction of cyclohexane in the solution but that isn't what it wants and I don't know exactly what the question is asking for. Can someone please explain to me how to do this problem?

*September 2, 2010*

**Chemistry: Raoult's Law**

If 0.380 mol of a nonvolatile nonelectrolyte are dissolved in 3.00 mol of water, what is the vapor pressure P(H2O) of the resulting solution? The vapor pressure of pure water is 23.8 torr at 25 C. I got this answer correct: 21.1 torr A solution is composed of 1.50mol ...

*September 2, 2010*

**Chemistry**

Thank you very much!

*August 23, 2010*

**Chemistry**

How can i rearrange this Clausius-Clapeyron equation so that 1/T2 is on one side? In P2/P1=delta H vaporization/R (1/T2- 1/T1) I am trying to find at At what temperature does acetone have Pvap= 111 mm Hg. Acetone, a common laboratory solvent, has Delta H vap= 29.1kJ/mol and a ...

*August 23, 2010*

**Physics 1112 Electric charge**

Still couldn't get the correct answer :[

*August 21, 2010*

**Physics 1112 Electric charge**

As shown in the figure, a square has sides of 8.0 cm with a charge of +6.0 µC at one corner (a) and with charges of -2.0 µC at the remaining three corners (b, c, and d). The figure is just a square with no measurements. Corner a being the top left corner, corner b ...

*August 21, 2010*

**torque**

A meterstick is found to balance at the 49.7 cm mark when placed on a fulcrum. When a 50.0g mass is attached at the 10.0cm mark, the fulcrum must be moved to the 39.2 cm mark for balance. What is the mass of the meterstick? All of the problems ive been doing i needed to find ...

*June 22, 2010*

**Physics 1111: Orbitals and Distance**

A planet has two satellite moons. Moon X has an orbital period of 2.27 days. Moon Y has an orbital period of about 3.40 days. Both moons have nearly circular orbits. Use Kepler's third law to find the distance of each satellite from the planet's center. The planet'...

*March 8, 2010*

**chem**

which of these substances dissolve in water? and are they elements or compounds? copper nitrate sodium hydroxide copper hydroxide copper oxide hydrochloric acid aluminum copper chloride hydrochloric acid

*October 8, 2007*

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