# Posts by abby

Total # Posts: 1,138

**Physics**

Electrons in a beam incident on a crystal at an angle of 300 have kinetic energies ranging from zero to a maximum of 5500 eV. The crystal has a grating space d=0.5A0, and the reflected electrons are passed through a slit .Find the velocities of the electrons passing through ...

**Physics**

An air rifle is used to shoot 1.0 g particles at 100 m/s through a hole of diameter 2.0 mm. How far from the rifle must an observer be to see the beam spread by 1.0 cm because of the uncertainty principle? Compare this answer with the diameter of the universe ( 1026 m).

**Physics**

To what voltages must we accelerate electrons (as in an electron microscope, for example) if we wish to resolve; a) a virus of diameter 12 nm , b) an atom of 0.12 nm, c) a proton of diameter 1.2 fm?

**Physics**

Electrons in a beam incident on a crystal at an angle of 300 have kinetic energies ranging from zero to a maximum of 5500 eV. The crystal has a grating space d=0.5A0, and the reflected electrons are passed through a slit .Find the velocities of the electrons passing through ...

**math**

6x48,7x47,8x46,9x45,10x44,11x43,12x42

**Physics**

Two converging lenses with focal lengths 5 cm and 30 cm are placed 35 cm apart. Rays from a very distant object are impinged on the lens system parallel to the principal axis. What is the refractive power of the combination of these two lenses?

**Pre Calc**

Thanks so much guys!!!!

**Pre Calc**

tan(x)=5 sin(x) for interval -π < x < π A) 0, 1.571 B) -1.571, 0, 1.571 C) -1.369, 0, 1.369 D) 0, 1.369

**geometry**

A guy wire is attached to the top of a 75 meter tower & meets the ground at a 65 degree angle. How long is the wire?

**Math**

tan(x)=5 sin(x) for interval -π < x < π

**Physics**

A photon of energy E strikes an electron at rest undergoes pair production, producing a positive electron(positron) and an electron, photon+electron produce positron+electron+electron The two electrons and the positron move off with identical momenta in the direction of the ...

**Physics**

The temperature of your skin is approximately 35C degrees. What is the wavelength at which the peak occurs in the radiation emitted from your skin?

**chemistry**

you must prepare 300 mL of .750M NaBr solution using 2M NaBr stock solustion. how many mL of stock solution should you use?

**apples**

Is the saying "an apple a day keeps the doctor away" true?

**Etymology**

Thankyou!

**Etymology**

I am doing a project on Fascinating Etymology Stories and was wondering if you guys know of any good websites with interesting stories of the origin of words, preferrably not words that came from a persons name. Thanks:)

**etymology**

how did wrigley come up the orbit. not the actually product but i need to know the orgin of the product name orbit. thanks:)

**chem**

Determine the volume of 0.240 M KOH solution required to neutralize each of the following samples of sulfuric acid. The neutralization reaction is shown below. H2SO4(aq) + 2 KOH(aq)--> K2SO4(aq) + 2 H2O(l) (a) 26 mL of 0.240 M H2SO4 thanks

**science**

determine the molar concentration of Ca^2+ and Cl- in a .075 M CaCl2 solution

**chemistry**

Calculate the molarity of each of the following solutions. 1. 61.9 g of C2H6O in 3.4 L of solution

**5th grade math**

this is soooooooooooooo BORING

**History**

If you could summarize the fighting in the Soviet Union between 1941 and 1944 into one sentence what would you say??

**child day care management,health,safety,and nutrit**

which of the following are the three major types of knowledge identified by piaget

**physical**

A helicopter flies over the arctic ice pack at a constant altitude, towing an airborne 142-kg laser sensor that measures the thickness of the ice (see the drawing). The helicopter and the sensor both move only in the horizontal direction and have a horizontal acceleration of ...

**Chemistry**

Kinetic energy is calculated from the formula KE = (1/2)mv2. Suppose a mass of 14.2 kg (m = 14.2 kg) is moving with a velocity of 750. ms-1 (v = 750. meters per second). Calculate the kinetic energy of this mass in units of Joules.

**Physics**

This is a conservation of angular momentum problem. Now, the formula for angular momentum is: L = Iw So basically, L before = L after: I1w1 = I2w2 The trick to solving these is to figure out what the change in moment of inertia is, and then apply the concept of conservation of...

**science**

if an astraunout could jump 40 cm on jupiter how high could he ir she jump on earth how about the moon also????? pleese help me im stuck on this question

**Math**

Thanks Ms. Sue

**Math**

$260

**Math**

Lyla deposited $250 in an account earning 4% simple interest. At the end on one year, how much was in the account, assuming no more deposits or withdrawals?

**Math symbols**

thank you!!!! :) :) :)

**Math symbols**

thanks and do you know what "*" means in math?

**Math symbols**

What does * mean in math? thanks for ur help Abby

**statistics**

Scores on the ACT test are normally distributed with a mean of 21.1 and a standard deviation of 4.8. If one ACT score is randomly selected, find the probability that it is greater than 20.

**physics**

how much work is being done if a 100 N box is lifted 3 meters off the ground???

**7th grade**

I am doing a battle chart in history class the I need to know who won the Gonzales battle Also i need the mexican leader and the texas leader and who won on in the battle of the concepcion and where the goliad battle took place and when it took place also i need all the grass ...

**math**

what multiplication fact could you use to find a number that can be divided evenly by 8 and by 9

**math**

If the volume of the ball is 288 pic cubic inches, what is the diameter of the ball?

**us history**

I need help finding information about the Industrial revolution. How it impacted American society economically, socially, politically, and morally. This needs to be a 500 word essay. Thanks for the help! :)

**Physics HELP!**

how is this equation right? when i multiplied all those numbers to get T1 i got a huge number...to plug it back in for T2 i would get a negative number...

**physical science with earth science**

Write a balanced chemical equation for the reaction for propane C3H8 burning in oxygen to for carbon dioxide and water vapor

**math**

880

**science**

A place or object used for comparion to determine whether something is in motion is called what?

**math**

60

**8th grade**

I don't understand constant rate of change can you give me some examples. The graph I have shows the depth of the water in a vase over 8 days

**social studies**

information about landform

**math**

61 devided by 6039

**Science**

if it takes 20 newtons to accelerate an object weighing 15 kg 0.1 meters per second squared to the west what is the force of kinetic friction?

**math**

A circular racetrack has a diameter of 200 meters. What is the approximate distance a car travels in meters for three full revolutions around the track? use 3.14 for pie.

**trig**

sin(pi/3)

**world issues- amazon deforestation**

I just need like facts on ways to stop deforestation. -_-

**world issues- amazon deforestation**

Are you asking me this?

**world issues- amazon deforestation**

Hi. I was assigned an essay that I have to get done by 2morrow. It is about Amazon rainforest deforestation. I have to sum everything up into 3 paragraphs. 1st paragraph- tell what's happening here; I already did this. 2nd & 3rd paragraphs- describe how you would stop ...

**Math**

Nope

**Math**

Rae runds a mile 20 times. Her average time is 5.2 mins. She wants to drop her slowest time 5.8 mins and find the ew average. Write and equation to find are her new average running time

**8th grade**

Maybe you should just make it as math instead of 8th grade. I suggest you post it agin.

**math**

Originally priced at $35 now on sale for 25% what proportion could you do to find d the discount of the price

**Math**

Originally priced ar 35 dollars now on sale for 25% find an proportion to find d. d/35 = 25/100

**10th grade geo**

An Important Fact About YOU! Worksheet.

**math**

jared spent 76 dollars in june. In july he spent 1/5 more money than he did in june which procedure can be used to determine the money he spent in july add 1/5 abd 75 multiply 1/5 abd 75 then add 75 multiply 1/5 and 75 divide 1/5 by 75 then subtact the result fron 75

**Pre-algebra**

Thank you for your help!

**Pre-algebra**

So 7t = -98. What is t?

**english**

If direct exposition means direct characterization, then true. Characterization is how the author helps you find out the personality traits of a character. Let's say if the story read; Yang was a very nice child from China. This would be DIRECT characterization. If the ...

**english**

Are you trying to ask if this is a correct sentence? If that is your question, than yes, it is a correct sentence. Only you need capitalization.

**8th grade math**

J=31-q or 31-q=J

**Social Studies**

WOW! That is ALOT of information!

**algebra**

Thank you I just didn't know if it was supposed to be a negative number or not. My math that I have is really confusing.

**algebra**

12 - 3b = what? for b = 4.3

**algebra**

a lot lot lot lot lot lot lot lot lot lot lot LOT!!! That is probably too big of a number to say.

**french**

check ending of tu form. Monica is intelligent. What is feminine adjective ending?

**physics**

Need equation: Mass of 4.24 kg acted on by external force that reduces velocity from 8.5 m/sec to 4.1 m/sec in 3.0 sec. Find magnitude of the retarding force?

**physics**

Mouse steals piece of cheese by rolling across the floor with a force of 5.0 N. With what acceleration does the cheese move? At what speed is the cheese rolling after 10 seconds?

**Spanish 1**

34. What's the opposite of alli. 36. Is lapiz masculine or feminine? Notice you are working with UN boligrafo.

**6th grade**

All you have to do to turn a fraction into a decimal is divide the numerator by the denominator. 5 divided by 8 = 0.625.

**math**

a bicycle rider left town at noon at traveled at a uniform rate of 15 miles an hour. at 2 pm the same day, a motorcycle rider left for the same place at a uniform rate 30 miles an hour higher. at what time did the motorcycle rider overtake the bicycle rider?

**science**

Mexico is actually the leading producer of silver followed by U.S., Canada, Australia, Spain, Peru, and lastly, Russia. Hope this helps Abby

**enviroment**

i have this quetion and answer thing and i am having troubles with the meanings can anyone help me?

**algebra**

Awesome! Thanks

**algebra**

If there was a problem like this: 2yx for y=8 and x=5, you would write it like this: 2(8)(5). Which do you multiply first? 8x5 then x2 or 2x8 then x5?

**science**

Yes. It will help us because it is an renewble energy souce. that is what I think.

**Science**

Should we use biomass?

**6th grade**

242

**math Trig**

find each ratio to 3 decimal places cot245degrees sec74degrees how do i do this?

**Social Studies**

Idunno

**Spanish**

sorry, I meant sentEnce.

**Spanish**

It mens where are you from. Dónde means where, and eres means you are. Put those in a scentance and it asks a question.

**math**

What is it......it is......????????????????!!!!!!!!!.

**4th grade science**

Wow this is a hard one.

**3rd grade**

the answer would be 50 because if he wants to be rounding to the nearest 10 then that's what it would be

**math**

2/24 1/4

**Calculus ll - Volumes**

No, actually. It is y=1. I sketched out the solid of the equations, and I believe it's a washer.

**Calculus ll - Volumes**

Find the volume of the solid obtained by rotating the region bounded by the given curves about the specified line. y=e^(-x), y=1, x=2; about y=2.

**math**

it is spelled like this eight million, forty-two thousand, one hundred seventy-six.

**H. Physics**

A plane travels 2.5 km at an angle of 35 degrees to the ground and then changes direction and travels 5.2 km at an angle of 22 degrees to the ground. what is the magnitude and direction of the plane's total displacement?

**H. Physics 11th grade**

while flying over the grand canyon, the pilot slows the plane down to one-half the velocity in item 3. If the wind's velocity is still 75 km/h toward the southeast, what will the plane's new resultant velocity be?

**11th grade**

A roller coaster moves horizontally, then travels 45 m at an angle of 30 degrees above the horizontal. What is its displacement from its starting point?

**6th grade, social studies**

is in goverment

**A&P**

___________are usually attached to rough endoplasmic reticulum and produce enzymes and other protein componds.

**Calculus**

let V be volume of the solid obtained by rotating about the y-axis the region bounded by y=sqrtx and y=x^2. find V both by slicing and by cylindrical shells. in both cases, draw a diagram to explain your method. I'm SO stuck!

**Calculus**

find volume of solid obtained by rotating region bounded by curves y=x and y=sq.rt x, about line x=2