# J

Most popular questions and responses by J-
## Physics

What is the thinnest film of a coating with n=1.42 on glass n=1.52 for which destructive interference of the red component (650 nm) of an incident white light beam in air can take place by reflection? I am confused on the n's and I have no idea what

*asked on April 21, 2008* -
## Us government

19. How is Snyder v Phelps an example of competing rights? Be specific in your answer. The court case of Snyder v phelps is an example of competing rights because the rights of privacy and speech are making distress and this came into conflict with the

*asked on November 18, 2017* -
## math-precalculus

A Ferris wheel is 50 meters in diameter and boarded from a platform that is 1 meters above the ground. The six o'clock position on the Ferris wheel is level with the loading platform. The wheel completes 1 full revolution in 6 minutes. How many minutes of

*asked on April 30, 2017* -
## Algebra

For questions 1-5 solve the equation. 1.-2v-7=23 (A)15 (B)8 ★ (C)-8 (D)-15 2. X/3-10=-12 (A)-6 (B)-66 (C)6 (D)66★ 3. d/3+10=7 (A)51 (B)20 ★ (C)0 (D)-9 4. 2(2-2x)=-3x (A)-4 (B)4 ★ (C)6 (D)0 5. 2.9n+1.7=3.5+2.3n (A)3 (B)-3 (C).3 (D)1 For questions

*asked on December 2, 2016* -
## Chemistry

A coffee cup calorimeter contains 25.0 grams water at 23.8 C A 5.00g sample of an unknown metal at an initial temperature of 78.3 C was dropped into the calorimeter. The final temperature of mixture was 46.3 C. Calculate the specific heat of the metal. The

*asked on March 19, 2013* -
## Physics

Medical x rays are taken with electromagnetic waves having a wavelength around .1 nm. What are the frequency, period, and wave number of such waves? ok I got the frequency as 3 * 10^18 Hz and the wave number as 6.3 *10^10 rad/m but I can't seem to remember

*asked on March 31, 2008* -
## Math page 167 algebra did you hear about...

Hi I need help with this one problem. It's on page 167 algebra with pizzazz. It has to use the addition method. 3x-5y=7 5x-2y=-1

*asked on February 5, 2013* -
## chemistry

Lithium metal dissolves in water to yield hydrogen gas and aqueous lithium hydroxide. What is the final concentration of hydroxide ions when 5.500 g of lithium metal is dropped into 750. mL of water?

*asked on October 4, 2010* -
## math

a cube with 2 in sides is placed on a cube with 3 in sides. then a cube with 1 in sides is placed on the 2 in cube. what is the surface area of the three cube tower?

*asked on March 21, 2013* -
## Math

A 6 inch personal pizza has 630 calories, with 240 of those from fat. A 16 inch pizza is cut into 8 slices. Estimate the number of calories in one slice of a 16 inch pizza.

*asked on February 10, 2017* -
## Wold History

Which of the following most directly resulted from the Neolithic Revolution? •Populations increased. •Complex cultures blended. •Religion became less important. 2. Which of the following best describes the emergence of social classes in early

*asked on September 13, 2016* -
## Physics

A closely wound rectangular coil of 80 turns has dimensions of 25 cm by 40 cm. The plane of the coil is rotated from a position where it makes an angle of 37 degrees with a magnetic field of 1.10 T to a position perpendicular to the field. The rotation

*asked on March 3, 2008* -
## chemistry

50cm3 of hydrogen is collected over water at 17 degree celsius and 750 mm Hg pressure.Calculate the volume of dry gas at S.T.P.The water vapour pressure at 17 degree celsius is 14 mm Hg?

*asked on May 28, 2015* -
## Physics

The crystalline lens of the human eye is a double convex lens made of material haveing an index of refraction of 1.44. Its focal length in air is about 8 mm which also varies. We shall assume that the radii of curvature of its two surfaces have the same

*asked on April 7, 2008* -
## Language Arts

The man quickly but carefully opened the oyster’s hard shell. A. quickly B. but C. carefully D. opened I think the answer is B but i am not sure. Can you check this and explain what a conjunction exactly is. Thanks!

*asked on April 18, 2016* -
## Math

You need to buy some chicken for dinner tonight. You found an ad showing that the store across town has it on sale for $2.89 a pound, which is cheaper than your usual neighborhood store, which sells it for $2.99 a pound. Is it worth the extra drive? First,

*asked on February 10, 2017* -
## Math Probabilities

A bag contains 9 red chips and 12 blue chips. Two chips are selected randomly without replacement from the bag. What is the probability that the two chips are the same color? That would be the probability of two reds PLUS the probability of two blues. The

*asked on March 6, 2007* -
## Chemistry

A chemist needs to prepare a buffer using the carbonate system (information in the table below) with a final pH of 6. Which components should they mix in water to product this buffer? H2CO3 HCO3- CO32- pKa 6.35 10.33 N/A

*asked on November 26, 2015* -
## math

4. Point E is located at (–2, 2) and point F is located at (4, –6). What is the distance between points E and F? a. square root of 52 b. square root of 28 c. 10 d. square root of 20 5. In which quadrant is the point (x, y) located if x is negative and

*asked on October 3, 2012* -
## math-precalculus

Outside temperature over a day can be modeled as a sinusoidal function. Suppose you know the temperature varies between 73 and 87 degrees during the day and the average daily temperature first occurs at 8 AM. How many hours after midnight, to two decimal

*asked on April 27, 2017* -
## science

Recall from previous activities in this lesson which era is sometimes referred to as the Age of Mammals. Locate and click on this section of the geologic time scale, and list the other possible names that could have been used to describe this era, and why?

*asked on May 1, 2017* -
## physics

A point charge Q= 4.60 uC is held fixed at the origin. A second point charge q=1.20 uC with mass of 2.80 * 10^-4 is placed on the x-axis 0.250 m away from the origin. (b) The second point charge is released from rest. What is its speed withn its distance

*asked on January 28, 2008* -
## Math

There were 7 times as many marbles in Box A as in Box B. After Joyce transferred 294 marbles from Box A to Box B, both boxes had the same number of marbles. How man marbles were there in Box A at first.

*asked on November 20, 2013* -
## Physics

Two small stereo speakers A and B that are 1.4 m apart are sending out sound of wavelength 34 cm in all directions and all in phase. A person at point P starts out equidistant from both speakers and walks so that he is always 1.5 m from speaker B. For what

*asked on April 21, 2008* -
## Physics

A transformer consists of 275 primary windings and 834 secondary windings. If the potential difference across the primary coil is 25 V, (a) What is the voltage across the secondary coil? (b) what is the effective load resistance of the secondary coil if it

*asked on March 18, 2008* -
## Math

Jerome has 1/4 of the groups video games at his house. Mario has 2/5 of the groups video games at his house. What fraction of video the groups video games is either at Jerome's house or Mario's house?

*asked on December 8, 2017* -
## trig

Juana and Diego Gonzales, ages six and four respectively, own a strong and stubborn puppy named Corporal. It is so hard to take Corporal for a walk that they devise a scheme to use two leashes. If Juana pulls with a force of 23 lbs at an angle of 18° and

*asked on December 12, 2013* -
## Chemistry

A chemist needs to prepare a buffer using the carbonate system (information in the table in the previous quetion) with a final pH of 10. Which components should they mix in water to product this buffer? Question options: H2CO3 HCO3- CO32-

*asked on November 26, 2015* -
## physics

A uniform metre rule of mass 90g is pivoted at the 40cm mark. If the rule is in equilibrium with an unknown mass m placed at the 10cm mark and a 72g mass at the 70cm mark,determine m.

*asked on November 11, 2017* -
## Algebra

I need help with my math pizzazz worksheet page 167 1.3x-5y=13 X-2y=5 2.7x-2y=-1 3x-4y=19 3.2x+3y=7 3x+4y=10

*asked on December 8, 2014* -
## Math

The hypotenuse (side C) of a triangle is 13 inches long. Which of the following pairs of measurements could be correct for the lengths of the other two sides of the triangle? (Note: N + 82 =C2) A. 2.5 inches,4 inches B. 2.5 inches, 6 inches C.5inches,

*asked on July 22, 2014* -
## icp

Charge q is 1 unit of distance away from the source charge S. Charge p is six times further away. The force exerted between S and q is _____ the force exerted between S and p.

*asked on September 20, 2010* -
## Physics

Coherent light of frequency 6.32 * 10^14 Hz passes through two thin slits and falls on a screen 85 cm away. You observe that the third bright fringe occurs at +- (plus or minus) 3.11 cm on either side of the central bright fringe. (a) How far apart are the

*asked on April 21, 2008* -
## math

The standard deviation of a sample taken from population A is 17.6 for a sample of 25. The standard deviation of a sample taken from population B is 21.2 for a sample of 30. The standard deviation of the sample mean differences is_____. (Round your answer

*asked on July 15, 2015* -
## Wold History

Having a hard time in World History! Please let me know if these are right and if not please tell me the answers! 1. How did the religious beliefs of the ancient Israelites differ from those of other nearby peoples? The Israelites believed in many gods,

*asked on September 22, 2016* -
## PHYSICS

a block is given an initial velocity of 3 m/s up the 22 degree plane. A.) How far up will the plane go B.) How much time elapses before it returns to its starting point. IGNORE FRICTION A) I got 1.2m B.) I got 1.6s I'm confused on this question: Both

*asked on February 24, 2016* -
## Math

A, B, C, and D are points on a line, and the lengths of the line segments are: AB = 12, BC = 4, CD = 7, and DA = 15. Which of the following is a possible order for the points? A.A,B,C,D B. A,C,D,B C. A,D,C,B D. A,C,B,D

*asked on July 22, 2014* -
## AP Calculus

Ship A is sailing due west at 8km/hr when it sees ship B northwest of its present position. If ship B is sailing due south at 3km/hr, then how close will they come on their courses?

*asked on January 9, 2017* -
## Physics

A mirror on the passenger side of your car is convex and has a radius of curvature with magnitude 18 cm. (a)Another car is seen in this side mirror and is 13 m behind the mirror, if the car is 1.5 m tall, what is the height of its image? I can't figure

*asked on April 7, 2008* -
## Chem

joules needed to melt 30.0 g of ice at 0 ∘C and to warm the liquid to 60.0 ∘C so i did Q=mFf which i set up like 30.g x 334 j/c = 10020 J then i'm sorta confused what i'm doing next. explain in detail please?

*asked on February 15, 2016* -
## Chemistry

Assume you have prepared 100.0 mL of a buffer solution using 0.400 mol of acetic acid (pKa = 4.74) and 0.400 mol of sodium acetate. The pH of this buffer solution is initially 4.74. After preparing this buffer solution, you added 55.0 mL of a 1.10 M NaOH

*asked on November 26, 2015* -
## orgo

A sample of naphthalene, which should be pure white, was found to have a grayish color after the usual purification procedure. The melting point was correct, and the melting point range was small. Explain the gray color.

*asked on January 30, 2013* -
## Chemistry

When normal atmospheric conditions are present, water is constantly being cycled between liquid and gaseous states by which of the following pairs of processes? A. Turgor pressure and filtration B. Melting point and condensation C. Evaporation and

*asked on July 27, 2014* -
## Physics

In designing a velocity selector that uses uniform perpendicular electric and magnetic fields, you want to select positive ions of charge +5e that are traveling perpendicular to the fields at 8.75 km/s. The magnetic field availabe to you has a magnitude of

*asked on February 18, 2008* -
## math

your brother is 1/3 your age.your sister is 6 years older than your brother. your sister is 10 years old. write and solve and equation to find your age a

*asked on January 31, 2017* -
## physics

A 4kg object is subjected to two forces, F1=2Ni-3Nj, and F2=4Ni-11Nj. The object is at rest at the origin at t=0. What is the objects acceleration? I know you use F=m*a Do you add the two F vectors together & take the square root to find the sum of F? ex:

*asked on September 19, 2010* -
## Algebra 2

What would be a real life example for the functions y=5x and y=5/x?

*asked on April 3, 2019* -
## managerial economics

A firm uses a single plant with costs C= 160 +16Q +.1Q2 and faces the price equation P= 96 – .4Q. a) Find the firm’s profit-maximizing price and quantity. What is the profit? b) The firm’s production manager claims that the firm’s average cost of

*asked on April 11, 2010* -
## physics

A parallel plate capacitor having plates 6.0 cm apart is connected across the terminals of a 12.0 V battery. (a) Being as quantitative as you can, describe the location and shape of the equipotential surface that is at a potential of +6.0 V relative to the

*asked on January 28, 2008* -
## Physics

A laser used to weld detached retinas emits light with a wavelength of 652 nm in pulses that are 20 ms in duration. THe average power expended during each pulse is .600 W. (a) How much energy is in each pulse, in joules and electron volts? (b) What is the

*asked on April 28, 2008* -
## physics

An object traveling 200 feet per second slows to 50 feet per second in 5 seconds. Calculate the acceleration of the object.

*asked on March 28, 2011* -
## physics

(a) How many excess electrons must be distributed uniformly within the volume of an isolated plastic sphere 30.0 cm in diameter to produce an electric field of 1150 N/C just outside the surface of the sphere? (b) what is the electric field at a point 10.0

*asked on January 27, 2008* -
## civics

Please check my answers! 1. The Nineteenth Amendment granted women the right to vote, but women had been fighting for years for this right. Before the Nineteenth Amendment was passed, which existing amendment could women have used to argue that they should

*asked on December 2, 2015* -
## College Math

farmer wishes to fence a rectangular area along the river bank. No fence is required on the side adjacent to the river. The material for the fence costs P16.00 per meter for the side parallel to the river, P12.00 per meter for the side perpendicular to the

*asked on August 25, 2010* -
## Chemistry

If you want to prepare 2.0 liters of a .25 M solution of NH4Cl, how many grams of the salt should you weigh out?

*asked on November 29, 2015* -
## Physics

A wooden boxcar is moving along a straight railroad track at speed v1. A sniper fires a bullet (initial speed v2) at it from a high-powered rifle. The bullet passes though both lengthwise walls of the car, its entrance and exit holes being exactly opposite

*asked on September 18, 2010* -
## Physics

We can reasonaly model a 75 W incandescent lightbulb as a sphere 6 cm in diameter. Typically, only about 5% of the energy goes to visible light; the rest goes largely to nonvisible infrared radiation. (a) What is the visible light intensity (in W/m^2) at

*asked on March 31, 2008* -
## Calculus grade 12

Explain why three directional vectors of the plane cannot me mutually perpendicular .

*asked on May 4, 2012* -
## organ chem

Why is thymol only slightly soluble in water, but very soluble in 1.0 M NaOH?

*asked on January 31, 2010* -
## compose

if 3.85 L of carbon monoxide was collected over water at 25 degrees celsius and 689 mmHg how many grams of formic acid were consumed?

*asked on December 8, 2009* -
## chemistry

An aqueous solution with a pH of 3.00 is diluted from 2.0 L to 4.0 L. Wht is the pH of the diluted solution?

*asked on May 5, 2009* -
## physics

A neutral conductor completely encloses a hole inside of it. You observe the outer surface of this conductor carries a charge of -12 uC. (a) Can you conclude that there is a charge inside the hole? If so, what is the charge? (b) How much charge is on the

*asked on January 28, 2008* -
## physics

A car with a mass of 1000kg is travelling at a constant velocity. The force from the engine is 200Newtons. Calculate the acceleration of the car using the formula f=ma. How long will it take this car to travel 0-60 mph (n.b. 1mph = 0.45m/s)

*asked on May 16, 2013* -
## Math

You need to replace the molding around a floor that is 15 ft. long & 23 ft. 6 in. wide. The molding sells for $0.50 per ft.. How much will the molding cost?

*asked on August 18, 2010* -
## Radiometric (Radioactive) Dating

How old is a sample that contains 125 atoms of U-235 and 375 atoms of Pb-207? ...Given that the half life values on my handout are 713 million years. *I do not even know where to start so could you please explain in steps too? Thanks.

*asked on March 29, 2015* -
## physics

a driver releases an air bubble of volume 2.0 cm^3 from a depth of 15 m below the surface of a lake where the temperature is 70C.

*asked on June 21, 2011* -
## Physics

You want to take a full length photo of your friend who is 2 m tall, using a 35 mm camera having a 50 mm lens. The image dimensions of 35 mm film is 24 mm by 36 mm, and you want to make this a vertical photo in which your friend's image completely fills

*asked on April 14, 2008* -
## Physics

Ronald Johnson, who is 80.0 kg, is running at 4.00 m/s when he suddenly jumps onto a stationary playground merry-go-round at a distance 1.50 m from the axis of rotation of the merry-go-round. Ronald Johnson is traveling tangentially to the edge of the

*asked on February 20, 2019* -
## 7th grade ss unit 1 lesson 13 test

I am stuck on the test ss 2b one the lesson 13 test Why is mining important to the economy of the Untied states? I but mineral I am so stuck on this test

*asked on March 6, 2017* -
## Math - Statistics

Suppose that the mean number of customers who arrive at the check-out counters each minute is 4. Create a Poisson Distribution with u (lamda) = 4 for x = 0 to 20. Compare your results to the histogram. 20 random numbers are generated with a Poisson

*asked on December 6, 2007* -
## Chemistry

The pH of a buffer can be predicted using the Hendersen-Hasselbach equation: pH=pKa+ log([conjugate base][conjugate acid]) The choice of the conjugate acid-base pair (as you did in the previous questions) determines the pKa value to be used in the H-H

*asked on November 26, 2015* -
## Pre-Calc (Circles). Please help :(

Five concentric circles with radii 1, 2, 3, 4, and 5 are drawn as shown dividing the circle of radius 5 into five regions: a circle of radius 1 and 4 annuuli (rings). What is the probability that a point chosen randomly from within the circle of radius 5

*asked on September 28, 2014* -
## physics

Calculate the energy released in the fusion reaction 2 3 4 1 1 H + 1 H->2 H +0 n. The atomic mass of 3 1 H (tritium is 3.016049 u. I am lost! help please!

*asked on May 5, 2008* -
## Biology

In an experiment, a researcher counts the number of oxygen bubbles produced by water plants placed under different colors of light. The researcher finds that water plants placed under white light release more oxygen bubbles than water plants placed under

*asked on July 27, 2014* -
## chem

.070g caffeine dissolved in 4 mL water. caffeine is extracted from aqueous solution 3 times with 2mL portions of methylene chloride. calculate total amount of caffeine that can be extracted into the 3 portions. caffeine has a distribution coefficient of

*asked on February 8, 2010* -
## calculus

Carbon-14 is a radioactive substance produced in the Earth's atmosphere and then absorbed by plants and animals on the surface of the earth. It has a half-life (the time it takes for half the amount of a sample to decay) of approximately 5730 years. Using

*asked on July 24, 2009* -
## math

What would be a real life example for the functions y=5x and y=5/x

*asked on April 3, 2019* -
## chemistry

Describe how to prepare 1 liter of 0.5N solution of HCl from concentrated HCl. H=1, Cl=35.5, spgr=1.19, 37.2%

*asked on September 7, 2010* -
## PHYSICS

A banked circular highway curve is designed for traffic moving at 60 km/h. The radius of the curve is 205 m. Traffic is moving along the highway at 40 km/h on a rainy day. What is the minimum coefficient of friction between tires and road that will allow

*asked on December 4, 2008* -
## arithmetic

How do I solve these questions? 3 1/3 - 2 2/5= 2.75 + .003 + .158 = 7/20 is equal to ? What is the value of the expression 2x2+ 3xy – 4y2 when x = 2 and y = - 4? 16x - 8 = If 2x – 3(x + 4) = - 5, then x = – 3(5 – 6) – 4(2 – 3) =

*asked on February 3, 2011* -
## Physics

When a solar flare erupts on the surface of the sun, how many minutes after it occurs does its light show up in an astronomer's telescope on earth? I am totally confused..help!

*asked on March 31, 2008* -
## chemistry

Using the volume 1.42mL of 95% ethyl alcohol that's required to dissolve 0.3g at 78 C, how do i find how much sulfanilamide that will remain in the mother liquor after the mixture is cooled to 0 C? (at 0 degrees=14mg/mL is the solubility) thanks

*asked on February 3, 2010* -
## organ chem

Using the volume 1.42mL of 95% ethyl alcohol that's required to dissolve 0.3g at 78 C, how do i find how much sulfanilamide that will remain in the mother liquor after the mixture is cooled to 0 C? (at 0 degrees=14mg/mL is the solubility) thanks

*asked on February 3, 2010* -
## W

Some people in a hotel are dropping water balloons from their window onto the ground below. The balloons take .15s to pass your 1.6m tall window. Where should security look for the raucous guest? Express your answer using tow significant figures.

*asked on September 23, 2015* -
## physics

A wooden crate weighs 780 lb. What force is needed to start the crate sliding on a wooden floor when the coefficient of starting friction is 0.40?

*asked on February 22, 2013* -
## Physics

Find the forces exerted by the two supports of a 4.0m, 50-kg diving board when a 60-kg woman stands at its end. The two supports are 0.8m apart. This time consider the mass of the diving board.

*asked on June 24, 2012* -
## PHYSICS

A) As a wind instrument warms up, the resonant frequencies of the instrument tend to slightly decrease. B) If the air in a concert hall warms up, the resonant frequencies of the string instruments will change precisely the same as the resonant frequencies

*asked on April 15, 2011* -
## calculus

A rectangular box is to be constructed from two different materials. The box will have a square base and open top. The material for the bottom costs $4.25/m2. The material for the sides costs $2.50/m2. Find the dimensions of the box with the largest volume

*asked on April 9, 2011* -
## physics

A sample of charcoal from an archaeological site contains 55 g of carbon and decays at a rate of .877 Bq. How old is it? ok I am totally lost, I don't know where to start

*asked on May 5, 2008* -
## Chemistry

Determine the mass of NH2CH2CO2Na and the volume of 0.150 M HCl solution required to make 1.35 L of a buffer solution at pH=10.75 and at a total concentration of 0.33 M. pKa(NH2CH2CO2H)=9.88. a.Mass of NH2CH2CO2Na: b. Volume of HCl solution: Hi Im sooo

*asked on November 16, 2016* -
## Science

A 6.90-g sample of solid NiSO4·6H2O was heated such that the water turned to steam and was driven off. Assuming ideal behavior, what volume would that steam occupy at 1.00 atm and 100.0 °C?

*asked on November 19, 2015* -
## Chemistry

Phosphorus pentachloride decomposes according to the chemical equation PCl5(g) PCl3(g)+Cl2(g) Kc=1.80 at 250 degrees Celsius A 0.222 mol sample of PCl5(g) is injected into an empty 3.25 L reaction vessel held at 250 °C. Calculate the concentrations of

*asked on March 3, 2013* -
## physics

A truck covers 40.0 m in 7.00 s while smoothly slowing down to a final velocity of 2.45 m/s.

*asked on September 16, 2010* -
## chem

.070g caffeine dissolved in 4 mL water. caffeine is extracted from aqueous solution 3 times with 2mL portions of methylene chloride. calculate total amount of caffeine that can be extracted into the 3 portions. caffeine has a distribution coefficient of

*asked on February 8, 2010* -
## AP Physics

While two forces act on it, a particle is to move at the constant velocity v = (3 m/s) i - (4 m/s) j. One of the forces is F1 = (2 N) i + (- 6 N) j. What is the other force? ( _____ N) i + ( _____ N) j Only two horizontal forces act on a 3.0 kg body that

*asked on November 13, 2008* -
## Physics

The internal resistance of a dry cell increases gradually with age, even though the cell is not used. The emf, however, remains fairly constant at 1.5 V. Dry cells must be tested for age at the time of purchase by connecting an ammeter directly across the

*asked on February 12, 2008* -
## Physics

A 450 uF capacitor is charged to 295 V. Then a wire is connected between the plates. How many joules of thermal energy are produced as the capacitor discharges if all of the energy that was stored goes into heating the wire? I am totally confused I don't

*asked on February 4, 2008* -
## Science/Biology/Physics

1. Giraffes have long necks that allow them to reach more food sources in their habitat. The long neck trait is an example of A. selection. B. adaptation. C. radiation. D. homology. 2. Which of the following is the most common kind of chemical bond in

*asked on July 23, 2014* -
## chemistry

The simple rule “Like dissolves like” is often used to describe the solubility of a substance in different solvents. Write a short paragraph discussing your evidence for this rule. Include in your discussion where you think this rule works best and

*asked on February 27, 2011* -
## Physics

A coil of wire with 200 circular turns of radius of 3 cm is in a uniform magnetic field along the axis of the coil. the coil has R=40 ohms. At what rate, in Teslas per second, must the magnetic field be changing to induce a current of .150 A in the coil? I

*asked on March 3, 2008*