Monday
August 31, 2015

Posts by elena


Total # Posts: 4,370

physics 1401
The time of the projectile motion is t=2v₀sinα/g sinα=gt/2v₀ =9.8•3/2•300=0.05 α=arcsin0.05=2.8°
June 21, 2015

PHYSICS
If ‘v’ is the speed of the bout and ‘u’ is the speed of the stream then 48/(v+u) + 48/(v-u) = 14 4/(v+u) = 3/(v-u) 48 v =7(v+u) (v-u) 4v-4u = 3v+3u => v=7u 48•7u = 7(7u+u)(7u-u) u=1 km/h
June 20, 2015

PHYSICS
5v₁+5v₂=150 25v₁-25v₂=150 v₁+v₂=30 v₁-v₂=6 v₁=18 m/s v₂ = 12 m/s
June 20, 2015

Physics
cesium-137: half-life 30.2 years, 0.3 MeV beta and 0.66 MeV gamma-ray emitter 1 Gray (Gy) = 1 joule of ionizing energy per kilogram Energy = 400 Gy•0.25 kg= 100 J 100J/0.3•10⁶•10⁻¹⁹=3.33•10¹⁵ disintegrations
June 18, 2015

science
it has been hypothesized that chloroplasts originated from photosynthetic cyanobacteria that became symbiotic inside a host cell. Which of the following observations provides the strongest evidence for this suggestion? A) microscopically, chloroplast appear similar to ...
May 11, 2015

Statistics
A criminologist is studying school violence, she selects a random sample of 25 adolescents aged 12 to 15 from a local middle school and asks the following,"How many times within the past school year have you been physically assaulted at school? She calculated the ...
February 27, 2015

Statistics
Suppose we would like to estimate the mean amount of money spent on books by students in the fall semester. We have the following data from 400 randomly selected students: mean=$205 and s=$40. Assume that the amount spent on books by students is normally distributed. Compute a...
February 27, 2015

math
are the following a function 1. y=x/2 my guess is yes 2. y=2x+1 my guess is yes 3.y=x^2 my guess is yes 4.y=mx+b im not sure
February 3, 2015

math
Does a machine that takes one quarter at a time into its input and produces one gumball in its output act like a function? my guess is YES
February 3, 2015

math
An equation is not a function if even one x value produces ____ corresponding y value(s). one less than one more than one zero for a my guess is more
February 3, 2015

math
classify the following number as rational or irrational: 4.1 My guess is Rational
February 2, 2015

math
the associative property allows you to change the order of terms in an expression. true or false my guess is True
February 2, 2015

math
okay thank you I don't know what an inverse is lol
February 2, 2015

math
I don't understand. so is it or is it not a function
February 2, 2015

math
Is y=3x^2-2 a function? my guess is NO
February 2, 2015

math
thank you!
February 2, 2015

math
Which relationship would most likely have a positive correlation? The amount of memory in computer, and the number of keys on the keyboard. The rate at which a train travels, and the time it takes for it to reach its destination. The number of tickets sold for a baseball game...
February 2, 2015

Math
5
February 2, 2015

Physics
the charge on a pith ball was measured as +40 nC. if the charge on an electron is -1.6 x 10^-19, how many electrons have been added or removed from the ball?
January 31, 2015

Chemistry - PLEASE HELP!!!
A 5.0 g n2o (laughing gas) that is inside a 12 mL cylinder used used to fill up a 800 mL whipped cream container. Beforehand, the container had air in it at 760 torr atmosphere pressure at 25 degrees celsius. Then, we will add the n2o/air mix to balloon until the pressure in ...
January 15, 2015

math
Does the Commutative Property apply to this situation? I ate dinner and read a book. I got = Yes.
January 14, 2015

math
If Jim is twice as old as Jerry plus six, Jerry is three years older than Tom, and Tom is 12, how old is Jim? I got = Jim is 36
January 14, 2015

Math
if x-7=14 what is the value of x-2 Can someone help me with this. I know the answer, I just want to know how something like this is solved.
January 8, 2015

earth science
the Julian calendar is the calendar we currently use. True or false. my guess is true
January 1, 2015

earth science
one reason the moon might be a better place than earth to study the universe is there is almost no atmosphere. True or False MY guess is false
January 1, 2015

earth science
During the summer _________ in India, wet air from the Indian ocean brings heavy rain to India.
December 30, 2014

earth science
air pollution in pennsylvania causes ______ in new england because the wind blows the pollution into new England. can someone please help, I cant find this anywhere.
December 30, 2014

SCIENCE
The burning of fossil fuels cause the earth to get warmer by putting carbon dioxide in the atmosphere and the carbon dioxide traps heat. MY GUESS: TRUE
December 22, 2014

EARTH SCIENCE
Smog is the worst in.. A. Chicago B. New York C. Los Angles MY GUESS: C. LOS ANGLES
December 22, 2014

Earth science
THANKS
December 22, 2014

Earth science
TRUE OR FALSE The burning of fossil fuels cause the earth to get warmer by putting carbon dioxide in the atmosphere and the carbon dioxide traps heat. MY GUESS: TRUE Isobars help meteorologists find fronts on weather maps. MY GUESS: FALSE A CLOUD IS A COLLECTION OF WATER ...
December 22, 2014

Geography
Thank you!
December 8, 2014

Geography
I have an essay that says.. "It has been said that Eastern Europe is a political region more than a physical region. Would you agree or disagree with this statement? You must provide a solid argument for your position." since it asks me for my opinion how do I write ...
December 8, 2014

Math
the average of five numbers is 16. Suppose 10 is added to five numbers. What is the average of the six numbers?
October 12, 2014

chemistry
Use activity coefficients to find the concentration of hydrogen ions in a solution of 90.0 mM butanoic acid and 0.05 M NaCl. The ionization constant of butanoic acid is Ka = 1.52 × 10-5. Take the size of C3H7COO– to be 500 pm. How do I calculate the ionic strength ...
October 3, 2014

math
two students are playing a math game . the object of the game is to make the least possible number by arranging the given digits inside absolute value bars on a card . in the first round , each player will use the digits 3,5,and7 to fill in the card. One student arranges the ...
September 25, 2014

Whats this
middle East
August 5, 2014

chemistry
4.62kj
June 23, 2014

Law
2. http://en.wikipedia.org/wiki/Diversion_program
June 10, 2014

physics
Here, u1 = 30 km/h t = 2 s u2 = 33.6 km/h a = (u2 – u1)/t a1 = (33.6 – 30)/2 = 1.8 ms-2 Similarly, a2 = (37.2 – 33.6)/2 = 1.8 ms-2 The acceleration of the vehicle is 1.8 ms-2
June 10, 2014

MATH
B. 5/51
June 9, 2014

MATH
I think it's B. The probabilities change every time a bill is pulled out. The probability of pulling out a 1 first is 5 out of 18 which is .227 then the probability of pulling out a 10 is 6 out of 17 because you don't replace the bill. since the events are independent ...
June 9, 2014

MATH
I think it's B. The probabilities change every time a bill is pulled out. The probability of pulling out a 1 first is 5 out of 18 which is .227 then the probability of pulling out a 10 is 6 out of 17 because you don't replace the bill. since the events are independent ...
June 9, 2014

business
This site will show you what you need http://www.opengroup.org/public/arch/p4/bus_scen/bus_scen.htm
June 8, 2014

algebra
This site shows you how to find terms of the sequence http://www.math-magic.com/sequences/next_term.htm
June 5, 2014

I may fail the 8th grade?
1. Take a deep breath. 2. I may be able to help. 3. post questions on your homework here and either ms.sue will help or me. BTW HELP we wont give you the answers but we will ensure help and explanations and you will get it right
June 5, 2014

Biology
A virus is a rudimentary biosystem that has some of the aspects of a living system such as having a genome (genetic code) and the ability to adapt to its environment. A virus, however, cannot acquire and store energy and is therefore not functional outside of its hosts. ...
June 5, 2014

biology
A capsid is the protein shell of a virus. It consists of several oligomeric structural subunits made of protein called protomers. A prion is an infectious agent composed of protein in a misfolded form.
June 5, 2014

Psychology
Read this and find your answer http://www.sirc.org/publik/drinking3.html
June 5, 2014

Psychology
What may ultimately make an abnormal behavior into a genuine mental disorder is if the behavior: 1. is maladaptive (harmful to self or others) 2. causes significant social impairment 3. causes significant occupational impairment 4. causes great personal pain and emotional ...
June 5, 2014

biology
The basic difference is their components. Viruses contain both nucleic acids (DNA or RNA) and a protein coat. Viruses cause infection by inserting their genetic material in a host cell. The host cell then replicates and reads the genetic material, making new viruses that ...
June 5, 2014

Algebra
there are 56 ways
June 5, 2014

Algebra
use the 8C3.now, can u evaluate the value of 8C3 ?.nCr = n!/r!(n-r)!it is the general formula of combination. also u have know about the "factorial", like 3! = 3 * 2 * 1 = 6 8C3, in this case knowed n=8 and r=3. by using the formula above, it can be 8C3 = 8!/3!(8-3...
June 5, 2014

Measurment
To answer this question, you'll need to find the surface area of the top of the container (which is a circle), along with the surface area of the side of the container.Note that the diameter of the container is given and is 6 inches; therefore, the radius is ... what? Note...
June 5, 2014

english
I think its either A. or C. but im not sure. Maybe A
May 28, 2014

english
In "A Man Called Horse," After his wife leaves him, Yellow Robe Behaves recklessly in battle because he A. would rather die than live with the bitterness he feels as a result of his lost pride B. is trying to gain membership in the society known as the foxes C. ...
May 28, 2014

english
I think its D
May 28, 2014

english
writers portray the personalities of characters A. only through revealing the characters private thoughts. B. through plot complication. C. only if the plot is not important to the story. D. through a variety of methods.
May 28, 2014

7 grade math
Thank you @Bobpursley!!
May 27, 2014

7 grade math
Consider two types of nonlinear equations. What unique quality does each possess and how does that quality cause the graph's unique shape? Name two unique examples of these shapes in real-world situations.
May 27, 2014

URGENT Physics help
F=kq₁q₂/r² q₂= F r²/kq₁= 7.2•10⁻²/9•10⁹•4•10⁻⁶= =2•10⁻⁶ C = 2μC Cpper rod is an electrical conductor; the others are insulators.
May 7, 2014

Physics
C=q/Δφ q=C Δφ
May 7, 2014

engineering
In the question I have some strenths and w/c ratios of some specimens and it is asking me about the range,molds?Also,How many specimens should be taken for each batch of concrete? This is a question before we learn it,so really have some understanding problems.
May 4, 2014

engineering
Hello guys.I got a homework and seem like I am stocked. a)What type of experiments should be done to find the relationship between the strength of concrete and water/cement ratio. b)what will be the range of the water/cement ratio? It would be great if you help.Thank you!
May 4, 2014

Math
To Damon: thank you so much for your help :))))))
April 29, 2014

Math
To Steve: I just copy that from my child's textbook as it is. Thank you for your great advice, I'll forward it to his math teacher.
April 29, 2014

Math
Hector has $450 and saves 20 per week. Tim has $1200and spends $30 per week.write a system equation for this situation
April 29, 2014

Physics 194
d•sinφ=kλ, tanφ=x/L. => d•x/L=kλ λ₁=dx₁/Lk λ₂=dx₂/Lk λ₁/λ₂=dx₁Lk/dx₂Lk= x₁/x₂ λ₂=λ₁x₂/x₁=630•0.21/0.26=508 nm
April 25, 2014

Physics
bsinφ=k λ sinφ=kλ/b, a) sinφ=1•630•10⁻⁹/0.020•10⁻³=0.0315 φ=1.8° b) sinφ=1•630•10⁻⁹/0.20•10⁻³=0.0035 φ=0.18° c) sinφ=1•630•10⁻⁹...
April 25, 2014

physics
a=ω²R, F(fr)=μN=μmg, ma =F(fr) => mω²R₁= μmg m(2ω)²R₂=μmg ω²R₁=4ω²R₂ R₂=R₁/4
April 24, 2014

Physics
E=0
April 19, 2014

physics
Imagine that F₂ is along the x-axis, F is along y-axis, and F₁ is directed to the “north-west”. The angle between F and F₁ is α. sin α = F₂/ F₁=1/2 α=30° Thus, the angle between F₁ and F₂ is 90°+30°...
April 19, 2014

Physics
W=mg
April 18, 2014

physics
1/λ₁ =Z²R[(1/n²) – (1/m²)] =2²•1.1•10⁷[(1/1²) –(1/3²)] λ₁=2.56•10⁻⁸ m 1/λ₂ =Z²R[(1/n²) – (1/m²)] =2²•1.1•10⁷[(1/2²) –(1/...
April 17, 2014

physics
E=5eV=8•10⁻¹⁹ J λ=h/p = h/sqrt(2mE) = =6.63•10⁻³⁴/sqrt(2•9.1•10⁻³¹•8•10⁻¹⁹)=5.5•10⁻¹⁰ m
April 17, 2014

physics
S=Energy per unit time/Area = Nhf/A= =4Nhc/πD²λ= =4•1.42•10¹⁸•6.63•10⁻³⁴•3•10⁸/π•(1.82•10⁻³)²•524•10⁻⁹= =2.07•10⁵ W/m² Electric ...
April 17, 2014

physics
(a) 1/do+1/di =1/F 1/di=1/F-1/do=1/48.5•10⁻³- 1/3.85•10⁸. di≃48.5•10⁻³m x/di=D/do x=D•di/do =3.48•10⁶•48.5•10⁻³/3.85•10⁸.= =4.38•10⁻⁴ m (b) 1/do₁+1/di₁...
April 17, 2014

physics
tan(α/2) =x/L => x=L tan(α/2) Coordinate of the second dark fringe is x=(2k+1)Lλ/d L tan(α/2)= (2k+1)Lλ/d d/λ =(2k+1)/tan(α/2)= (2•2+1)/tan3.6°=79.5
April 17, 2014

Physics
(i) h=gt²/2 t=sqrt(2h/g)=sqrt(2•10000/9.8)=45.2 s. (ii) v=800000/3600 = 222.2 m/s s=vt =222.2•45.2 =10044 m (iii) x=0 (since the horizontal speed of the cargo is constant)
April 14, 2014

Physics
The speed of sound at 20°C v=343 m/s s=vt=343•3=1029 m
April 14, 2014

Physics
If the detector (radar)is at rest and the source (moving car that reflects the sound)) is moving away from the detector, the observed frequency f is less than the actual frequency f₀. The speed of sound v =343 m/s f=f₀v/(v+V) V=v(f₀-f)/f =343•(1.5-1.4)&#...
April 14, 2014

physics
KE=mv²/2 v²= 2•KE/m a= v²/2s F=ma=mv²/2s= 2m•KE/2s m= = KE/s=10/0.005 =2000 N
April 14, 2014

physics
v₁ =910 m/s m₂=1000 kg v₂=10000 m/s u= 1000 m/s m₁=? (m₁+m₂)u = m₁v₁ +m₂v₂ m₁=m₂(v₂-u)/(u-v₁)= =1000(10000-1000)/(1000-910) = 100000 kg
March 25, 2014

Trigonometry
find sin2x, cos2x, and tan2x if sinx= -2/sqrt 5 and x terminates in quadrant III
March 25, 2014

physics
v=v₀+at = 10.5+(4.4•4.2) = 28.98 m/s
March 25, 2014

Phyics
1. x: ma=mg•sin α –F(fr) y: 0=-mg•cos α +N ma=0 0= mg•sin α-μN= = mg•sin α-μ•mg•cos α tan α = μ =0.4 α=arctan0.4 =21° 2. ma=mg•sin α – μ₁mg•cos α a=g&#...
March 20, 2014

Physics
The blocks move with the same acceleration ‘a’ F(fr)= μN m₁g=W₁ => m₁=W₁/g= 77/9.8=7.86 kg m₂g=W₂ => m₂=W₂/g= 114/9.8=11.63 kg x: m₁a=m₁g•sin α -μ₁N₁-T y: 0=-m₁g...
March 20, 2014

physics
1. PE=KE PE=mgh=mg•s•sinα KE=mv²/2 mg•s•sinα=mv²/2 v=sqrt(2g•s•sinα) = =sqrt(2•9.8•1.8•sin22°)=3.64 m/s v=at => a=v/t s=at²/2= vt²/2t=vt/2 t=2s/v=2•1.8/3.64 =0.99 s 2. t₁=2t=0.99...
March 20, 2014

Science
p=mv=20•5 =100 kg•m/s
March 20, 2014

Physical Science
(60 W•24hours •30 days)/1000=43.2 kW•h 43.2•0.1$=4.32$
March 20, 2014

Physics
T=ma=mv²/L m=TL/v²
March 20, 2014

Physics
An angular speed ω=v₁/R₁=v₂/R₂ v₁/v₂= R₁/R₂=9.8/6.6 =1.48
March 20, 2014

Physics
T=ma=mv²/R=1.9•2.8²/2.3= 6.48 N
March 20, 2014

Physics
B= μ₀•I/2π•d= μ₀•q•t/2π•d q=2π•d•B/ μ₀•t= =2π•28•7.3•10⁻⁵/4π•10⁻⁷•2.2•10⁻³=4.64•10⁶ C
March 20, 2014

Physics
L is the length of the solenoid N is the number of turns d is the diameter of the wire r is the radius of the solenoid (of the turn) Resistance R=ρx/A=4ρx/πd² ρ=1.6•10⁻⁸ Ω•m μ₀=4π•10⁻⁷ H/m U...
March 20, 2014

MATH
explain how to construct a perpendicular bisector
March 12, 2014

Science
the process in which body cells are duplicated in order to grow and repair body tissues is called
March 6, 2014

Physics
p=mv
February 27, 2014

physics
W=mg
February 27, 2014

physics
mg =ma =mv²/R v=sqrt(gR)=sqrt(9.8•0.6)=2.4 m/s
February 26, 2014

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