Friday
May 27, 2016

# Posts by J

Total # Posts: 919

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 the image area. (a...
April 14, 2008

Physics
A certain digital camera having a lens with focal length 7.5 cm focuses on an object 1.85 m tall that is 4.25 m from the lens. (a) How far must the lens be from the photocells? (b) How tall is the image on the photocells? Is it erect or inverted? (c) A SLR digital camera often...
April 14, 2008

science
Why is the mechanical advantage of an inclined plane less than 1
April 13, 2008

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 magnitude. (a) Find the...
April 7, 2008

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 this one out! help ...
April 7, 2008

Physics
my book says the answer is 39 degrees..
April 7, 2008

Physics
If the critical angle for light at an interface between certain substances is 54.2 degrees, what is the polarizing angle at this same interface? I am confused!
April 7, 2008

math riddle ALGEBRA WITH PIZZAZZ
How does a hawaiian baritone laugh? A -low- ha
April 6, 2008

Physics
During 2004, japanese scientists successfully tested two solar sails. One had somewhat complicated shape that we shall model as a disk 9 m in diameter and 7.5 um thick. The intensity of solar energy at this location was about 1400 W/m ^2. (a) What force did the sun's light...
March 31, 2008

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 the surface of the ...
March 31, 2008

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 how to get period.
March 31, 2008

Physics
In TV picture, faint, slightly offset ghost images are formed when the signal from the transmitter travels to the receiver both directly and indirectly after reflection from a building or some other large metallic mass. In a 25 inch set, the ghost is about 1 cm to the right of...
March 31, 2008

Physics
ok thank you! I wasn't using the right numbers!
March 31, 2008

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!
March 31, 2008

Physics- energy
Question 1The best way to determine levelness is to see if slope of velocity versus time for both directions are equal but opposite. Question 4:The greatest magnitude of net force is when the cart is going uphill. Uphill has a Net force greater by twice friction. It is not ...
March 27, 2008

cultural diversity
What is a current issue between Native Americans and the Federal Government. Indentify the legislation that you think is linked to the issue, and explain why you think there is a connection. Help Please!
March 25, 2008

Physics
An inductor used in a dc power supply has an inductance of 12 H and a resistance of 180 ohms and carries a current of .300 A. (a) How much energy is stored in the magnetic field? (b) At what rate is thermal energy developed in the inductor? ok once again I got part (a) .540 J...
March 18, 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 is connected across ...
March 18, 2008

Physics
An inductor used in a dc power supply has an inductance of 12 H and a resistance of 180 ohms and carries a current of .300 A. (a) How much energy is stored in the magnetic field? (b) At what rate is thermal energy developed in the inductor? ok once again I got part (a) .540 J...
March 18, 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 is connected across ...
March 18, 2008

Chemistry
What is the mass in grams of 1.02X10^24 molecules of NaCl?
March 11, 2008

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 takes .06 s. What is the...
March 3, 2008

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 don't know if I ...
March 3, 2008

Physics
ok I am confused, because I have the answer in the back of my book it says it is D/square root of 2
March 3, 2008

Physics
If a magnetic flux passes through a circular coil when its diameter D, what should be its diameter (in terms of D) so that only half as much flux passes through it in the same field? Assume that the magnetic field is uniform over the area in both cases. I am totally lost! I ...
March 3, 2008

english
Okay. Thank you for your help.
February 26, 2008

english
Do I have to make them specific if that is my top sentence for a paragraph that relates back to this thesis: The characters of the novel demonstrate how misery drives people to do things they would not normally do.
February 26, 2008

english
how can i word this differently: People advise others to stay clear of the horrible consequences of despair.
February 26, 2008

English
Thank u so much. that helped a tons. So the other ones don't need any commas? (that's what i'm worried about). thanks again.
February 26, 2008

English
Can someone please check the grammar in the following sentences. Please. 1. Normally Victor takes pleasure in spending time with his family; however, when he feels down he opts for solitude. 2. The creature begins to feel alone and vows revenge. 3. This is the same creature ...
February 26, 2008

Physics
An electron beam of a TV picture tube is accelerated through a potential difference of 2.00 kV. It then passes into a magnetic field perpendicular to its path, where it moves in a circular diameter of .360 m. What is the magnitude of the field? I am lost. I keep getting the ...
February 25, 2008

english
Thanks
February 25, 2008

english
when citing long quotes do i put the parentheses with the page # after the period or before? thanks for ur help.
February 25, 2008

English
thanks
February 25, 2008

English
Is this a strong thesis: The characters of the novel demonstrate how misery drives people to do things they would not normally do.
February 25, 2008

English
does this need a comma: Over six billion souls in the world and they all have something in common. Thanks for ur help.
February 25, 2008

Physics
A beam of protons is accelerated through a potential difference of 0.745 kV and then enters a uniform magnetic field traveling perpendicular to the field. (a) What magnitude of field is needed to bend these protons in a circular arc of diameter 1.75 m? (b) What magnetic field ...
February 25, 2008

science
25. A 34g Cu * 1 mole Cu/ 63.54 which equals .54 26. A
February 25, 2008

History
HOW AND WHY DID WARFARE CHANGE IN THE 20TH CENTURY?
February 21, 2008

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 0.550 T. (a) What ...
February 18, 2008

Math
What is the area of a circle that is 6m in square centimeters
February 13, 2008

english
What does nature is not benign mean?
February 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 terminals of the cell...
February 12, 2008

Physics
ok yea! I got it now..I just made a stupid mistake with my algebra! Thank you!
February 4, 2008

Physics
ok I used 1.512 = 1.484[1+ alpha (34-20)] and the answer in the back of my book isn't the answer I am getting
February 4, 2008

Physics
A certain resistor has a resistance of 1.484 omega at 20 degrees celsius and a resistance of 1.512 omega at 34.0 degrees celsius. What is its temperature coefficient of resistivity? ok..I used a temperature equation but I can't get the right answer. so maybe I am doing ...
February 4, 2008

Physics
(a) How much charge does a battery have to supply to a 5.0 uF capacitor to create a potential difference of 1.5 V across its plates? How much energy is stored in the capacitor in this case? (b) How much charge would the batter have to supply to store 1.0 J of energy in the ...
February 4, 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 even know where to...
February 4, 2008

Chemistry
The density of gold is 19.3 g/cc (g/ml). If a gold rod has a diameter of 4.20cm and 8.0 cm long. What is the mass? I just need to know if I did this right... r= 2.1 3.14 x 2.1^2 x 8.0 = 110.835g 19.3 g/cc x 110.835g = 2139.12 g/ml m = 2139.12
February 3, 2008

Physics
(a) If you use two quarters 2.00 mm apart to make a parallel plate capacitor, what is its capacitance? Measure the necessary quantities. (b) If you connect your capacitor in part (a) across 12 V potential difference, how much excess charge will flow onto each quarter? I am ...
January 30, 2008

Physics
A paralle plate air capacitor has a capacitance of 500.0 pF and a charge of magnitude 0.200 uC on each plate. The plates are 0.6 mm apart. (a) What is the potenetial difference between the plates? (b) What is the area of each plate? (c) What is the electric field magnitude ...
January 30, 2008

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 potential of the ...
January 28, 2008

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 from the origin is (i...
January 28, 2008

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 inner surface of the ...
January 28, 2008

physics
During a violent electric storm, a car is struck by a falling high-voltage wire that puts an excess charge of 850 uC on the metal car. (a) how much of this charge is on the inner surface of the car? (b) How much is on the outer surface? ok...I didn't think there was any ...
January 27, 2008

physics
ok..thank you very much. I thought that is what you would do for part b but I wasn't sure! Thank you!
January 27, 2008

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 cm outside the ...
January 27, 2008

physics
ok so the length of the sides doesn't matter in this case? I am confused! haha
January 25, 2008

physics
ok the question is....A point charge of 8.00 nC is at the center of a cube with sides that are 0.200 m. What is the electric flux through (a) the surface of the cube, (b) one of the six faces of the cube? ok so would I just use Gauss's law 4* pi*k*q? even though that is ...
January 25, 2008

physics
(a) What is the total negative charge, in coulombs, of all the electrons in a small 1.00 g sphere of carbon? One mole of C is 12.0 g, and each atom contains 6 protons and 6 electrons. (b) Suppose you could take out all the electrons and hold them in one hand, while the other ...
January 21, 2008

English
please can somebody tell me the effects of a metaphor, onomatopoeia and extended personification are. thank you please reply
January 19, 2008

social
what is the name of the publication of the American automobile assocation?
January 9, 2008

Math - Statistics
Oh i'm sorry: The check-out can process a total of four customers every minute.
December 6, 2007

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 distribution for u (lamda...
December 6, 2007

chemitsry
The directions say for each of the following use appropriate chem properties to explain the following observations. What would be observed on the surface of zinc and silver if they are placed in separate solutions of copper (II) sulfate? I am not really sure what they're ...
November 19, 2007

Biology - photosynthesis
1. In measuring the amount of ATP and NADPH consumed by the Calvin cycle, you find 30,000 molecules of ATP consumed but only 20,000 molecules of NADPH. WHere did the extra ATP molecules come from? A) Chlorophyll B) photosystem II C) cyclic electron flow D) noncyclic electron ...
November 17, 2007

Science
USA. Waste. Thats the topic the title of my work to give you what i'm talk about.
November 6, 2007

Science
SUM1 PLEZ HELP ME
November 6, 2007

Science
Topic: Waste Minimization How bad is it locally (USA)?
November 6, 2007

spaish
Hello, Hi
November 6, 2007

Science
Who is creating the most waste?What is suggested that we do to curve the waste problems? What is already being done to help curve the waste problem?
November 5, 2007

science
what are the future effects/impacts of landfills?
November 5, 2007

science
Who is creating the most waste?What is suggested that we do to curve the waste problems? What is already being done to help curve the waste problem?
November 5, 2007

Science
What are waste minimization components?
November 5, 2007

Science
How is waste minimization bad locally in USA?
November 5, 2007

social studies
What is a dissenter?
October 25, 2007

GRAMMAR
A comma?
October 24, 2007

GRAMMAR
Do I use a semicolon correctly in this sentence? "This caused David to become a spectator rather than a sufferer; covering his misery with mercy and sadness with compassion (3.2.4)."
October 24, 2007

REPOST biochem
i don't understand this why can carboxyl and phosphate groups act as acids? as in, what makes an acid?
October 18, 2007

Biology
nevermind i figured it out
October 18, 2007

Biology
What's high specific heat is mainly a consequence of the: A) high specific heat of oxygen and hydrogen atoms B) inability of water to dissipate heat into dry air D) absorption and release of heat when hydrogen bonds break and form E) fact that water is a poor heat ...
October 18, 2007

Biology
Why can carboxyl and phosphate groups act as acids?
October 18, 2007

Biology
General question: do polypeptides only make up proteins and not carbohydrates? and can they be formed by dehydration synthesis?
October 18, 2007

Chemistry
0.520 g
September 5, 2007

English
Need a good thesis statement about the gender protrayal in Jane Eyre. This is what I ahve, but looking for other suggestions: The patriarchal society of the Victorian Era causes Jane to struggle to become independent and to prove that men and women are both animated by the ...
September 4, 2007

alg.
solve the system by addition: -5x-9y = -5 x+5y=-15 I've tried this one over and over, but I can't seem to get the right answer. I don't even really know where to start. each time i try to do it, i go about it a little differently and i'm completely lost, pls ...
August 14, 2007

ENGLISH
DOES ANYONE HAVE A WEBSITE TO LOOK UP BOOKS? PLEZ HELP! Here is a good one: http://www.gutenberg.net Be aware, though, that not all books are available online. If the book is still under copyright, it's unlikely to find it or study guides for it online. =)
May 14, 2007

Question
Do you the different comma's? I don't know what your exact question is, but here is a webpage that includes excellent explanations and examples for the different comma uses: http://grammar.ccc.commnet.edu/grammar/commas.htm =)
May 14, 2007

Global
Stalin said that ideas are more powerful than guns, we dont let our opponents have guns why should we let them have ideas. How are ideas more powerful and wat are some examples of this. Also why is it more important Here's one idea to draw on: http://www.google.com/search?...
May 3, 2007

Math
Let x represent the number which shows up when a balanced die is rolled. Then x is a random variable with a uniform distribution. Let x-bar denote the mean of the numbers obtained when the die is rolled 32 times. For samples of size 32, which of the following statements ...
April 22, 2007

math
A variable is normally distributed. 42% of the possible observations of the variable lie between 20 and 28. What information does this give you about the graph of the normal curve for this variable? I am not sure how to exactly explain this. The only thing I can imagine it ...
April 22, 2007

math
No idea how to do this. I looked in my book and there usually is a data set present to get the first, second and third quartile. The lifetimes of lightbulbs of a particular type are normally distributed with a mean of 392 hours and a standard deviation of 9 hours. Find the ...
April 22, 2007

Government
A police officer has arresteda suspect and produced evidence of wrongdoing.List 3 questions you would ask the officer to determine whether the freedom and the security of the suspect have been violated. Can I just list 3 questions from the miranda rights or would that just be ...
March 28, 2007

science
How is homeostasis maintained in the digestive system? Homeostasis is maintained by negative feedback - For example.....a thermostat controlling temperature. When the temp goes down, the thermostat senses it and turns on the heat. When it gets to hot, negative feedback occurs...
March 27, 2007

Biology
What is the formula for field of view? Thank you for using the Jiskha Homework Help Forum. Here are some sites that hopefully will help you: 1. (Broken Link Removed) 2. http://www.rainbowcctv.com/tech/angle.html 3. http://en.wikipedia.org/wiki/Depth_of_field
March 8, 2007

Math
My question is to get a better understanding of this. Basically, these two problems, I did it WITHOUT replacement. So I would multiply each defects and so forth. My question is, would I have to subtract the total from 1 in the second question? I am not exactly clear on when to...
March 6, 2007

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 probability of two ...
March 6, 2007

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