Wednesday
December 17, 2014

Posts by Andrea

Total # Posts: 698

Physics
Why do ocean waves break as they approach the shore? Is it because of the principle of superposition. Would it be described as constructive or destructive interference? I believe it's constructive interference as the two waves combine the amplitude is large which causes ...
February 29, 2008

Physics
A block oscillates on a spring and passes its equilibrium position with a speed of .157m/s. It's kinetic energy is zero when the block is at the distance of .1m from equilibrium. Assume no friction between the block and the table. What is the period of its oscillation? v=....
February 29, 2008

Physics
The frequency of a stationary siren is 1500 Hz when measured by a stationary observer. If an observer moves away from the siren at mach number .85 what is the frequency he hears? (assume room temperature so that velocity of the air is 340m/s) I know that I would use f'=f (...
February 29, 2008

Trig
Verify that each of the following is an identity. tan^2x-sin^2x=tan^2xsin^2x I can get it down to cos^2 on the right, but cannot get it to work out on the left. secx/cosx - tanx/cotx=1 On the left I got down to 1-tan^2, but that clearly doesn't equal 1.... 1-2cos^2x/...
February 28, 2008

History
Eisenhower
February 28, 2008

history
what is the slaves experiences in mid19th century america
February 26, 2008

american history
what businesses came under the scrutiny of the sherman antitrust act in the 1800s?
February 18, 2008

precalc
thanks
February 18, 2008

precalc
Hi. Can someone help me with this? Simplify: (sin^2x)(cos^2x)+(sin^4x) The answer is sin^2x, but I have no idea how to get there! Thanks!
February 18, 2008

science
Suppose you have monohybrid pea plants in your garden and find that they produce round seed to wrinkled seeds in the ratio of 3:1. If the allele are designated (R & r) respectively, what is the probable genotypes of the wrinkled seeds which were produced (F1)? RR & Rr RR only...
February 15, 2008

Math
Find the value of tan(1/2sin^-1 15/17) and sin[pi/2-cos(1/2)] Thanks.
February 13, 2008

Math
how would you factor 4x-x^2-3/ x-1...so that x-1 would cancel out? could you explain step by step..plz
February 8, 2008

Physics
A string of mass m=.1kg is stretched to where its length is L=20m. What is the tension force applied to the string if it takes a pulse 2 seconds to get from one end to the other? m=kg L=20m T=4s mass density =m/L = .1/20 = kg/m Tension =? I know v=sqrt(F_t/mass density) But I...
February 6, 2008

Physics
Find the instantaneous velocity of a pendulum at the instant when its bob is at the height equal to half of its maximum height h=(h_max/2) above teh equilibrium point. Assume the max velocity of the bob during each oscillation is v_max= 2m/s. Wouldn't PE=KE mgh=1/2mv^2 gh=...
February 6, 2008

Physics
A swing is 2m long. how often do you need to push it to increase its swing's amplitude the most? L=2m When amplitude is the most KE=0 and PE is at its maximum. But i'm not completely sure how to solve this problem.
February 6, 2008

Physics
A mass m=.5kg on a spring with a spring constant. It is displaced by the distance x_max =20cm (.2m) from equilibrium on a frictionless horizontal surface. At the time t=0s the mass is released and it begins to oscillate. Assume that T=3.14s. Find the following for when t=0, T/...
January 30, 2008

Physics
Find the instantaneous velocity of a mass on a spring oscillating on a horizontal frictionless surface at the instant when its displacement is half of its maximum displacement x=(x_max/2). Assume the max velocity of that mass during each oscillation is v_max= 2m/s. I know that...
January 30, 2008

Math
Which type of dilation is determined by a scale factor of 10? enlargement reduction congruence transformation none of these
January 15, 2008

math
how would you solve for x? can you explain step by step? 40 = [(x+2.8)/2]*8.5
January 12, 2008

Math : Algebra
how would you solve for x? can you explain step by step? 40 = [(x+2.8)/2]*8.5
January 11, 2008

Math : Algebra
how would you solve for x in this equation? 40.0 = 0+ (x + 2.8)/2multiplied by(8.50)
January 11, 2008

history
Why did Germany invade Poland in 1941? =]
January 3, 2008

History
Why did Japan invade China in 1937? thank you so much =]
January 3, 2008

History
Why did Japan invade China in 1937? thank you so much =]
January 3, 2008

Bio
Describe what can happen to the three-carbon molecules made in the Calvin cycle.
December 1, 2007

Physics
A box of mass 1kg is placed on a table and is connected to a hanging mass m by a string strung over a pulley. If the coefficient of kinetic friction between the box and the table is .3 and the box slides at a constant speed of .5m/s what is the weight of the hanging mass? to ...
November 14, 2007

Physics
You have just discovered a planetary system consisting of a star (Dagobahr) and its two planets: Rool and Krau. Planet Rool has an average orbital radius 3 times as big as planet Krau. If planet Rool orbits Dagobahr in 2 earth years (1earth year = 365 days). a) how long is the...
November 14, 2007

Physics
A box of mass 1kg is placed on a table and is connected to a hanging mass m by a string strung over a pulley. If the coefficient of kinetic friction between the box and the table is .3 and the box slides at a constant speed of .5m/s what is the weight of the hanging mass? ...
November 14, 2007

Physics
A box of mass 1kg is placed on a table and is connected to a hanging mass m by a string strung over a pulley. If the coefficient of kinetic friction between the box and the table is .3 and the box slides at a constant speed of .5m/s what is the weight of the hanging mass? ...
November 14, 2007

Physics
complete the statement: in recoil a)the initial momentum is zero b)the object sticks together after collision c)the total kinetic energy is conserved d)the final speeds of the object are the same b) is wrong. I think it's either c) or d) but i'm going to go with c).
November 14, 2007

Physics
a rock is thrown straight up which of the following statemetns concerning the net force acting on the rock at teh top of the path is true? assume air resistance is negligible. a)it's equal to the weight of the rock b) it is instantanwously equal to zero c) it's ...
November 14, 2007

Physics
two objects collide when sliding on a fricitonless horizontal surface. Which quantity is conserved during their collision? a) velocity b) momentum of both objects c)energy d) momentum of each object isn't c) or b) correct? I really think it's c)
November 14, 2007

Physics
a rock suspended from a string moves downwards at constant a=g. Which of the following is true concerning the tension in the string? a) the tension is zero b)the tension is equal to the weight of the rock c)the tension is less to the weight of the rock d)the tension is greater...
November 14, 2007

Physics
Complete the following statement: The term net force most accurately describes: a) quantity that causes displacement b) quantity that keeps the object moving c) the mass of the object d) the quantity that changes the velocity of an object c) is not the right choice. I believe ...
November 14, 2007

Physics
Europa, a moon of Jupiter has an orbital diameter of 1.34x10^9m and a period of 3.55 days. What is the mass of Jupiter? d=1.34x10^9m T=3.55days = 30672s M=? r=71492000m rm=6.7x10^8 r-total=7414492000m r^3/t^2=GM/4pi^2 741492000^3/306720^2=6.67X10^-11(M)/4pi^2 I got m=2.56x10^...
November 12, 2007

Physics
The mean radius of the Earth is R=6.38x10^6m. At what distance above the Earth's surface will the acceleration of gravity be 4.905m/s^2? F_g=(Gmme)/r^2 4.905=6.67x10^-11(5.98x10^24)/r^2 The mass cancel out so that is how I got the above answer. r=9017663m Is this the ...
November 12, 2007

Physics
A 2.1kg brass ball is transported to the Moon. a)What is the mass of the brass ball on the earth and on the moon? Wouldn't it be 2.1kg for the earth as well as for the moon? b)Determing the weight of thee brass ball on the earth. F_g=(G*m_ball*m_earth)/r^2 =20.58N c) the ...
November 12, 2007

Physics
"the total angular momentum of an object changes when a net external force acts on the system." This statement is: a)always true b) never true c) sometime true, it depends on the force's direction d)sometime true, it depends on the force's point of ...
November 7, 2007

Physics
A lever is 5m long. The distance from fulcrum to the weight to be lifted is 1m. If the worker pushes on the opposite end with 400N, what is the max weight that can be lifted? l=5m h=1m F=400N F_g=? torque=F_g*l I first must find torque so that I can plug it into the above ...
November 7, 2007

Physics
Is the answer to this 4? If the filament resistance in an automobile headlamp is 3 ohms, how many amps does it draw when connected to a 12-volt battery?
October 27, 2007

Physics
Consider a roller coster car moving along a track from point A to point B to point C. a)if the roller coaster car starts from rest at point A (30m above the bottom of a dip (point b). What would be the speed of the car at the top of the next hill (point C), which is 20 m above...
October 17, 2007

Physics
If the net work done on an object is positive then the object's energy is ...? The object's energy would also increase since W= energy right? The object's energy wouldn't increase or decrease.
October 17, 2007

Physics
Compared to yesterday you did 3 times the work in one third the time. To so so your power output must have been: a) the same as yesterday's power output b)one third of yesterday's power output c)3 times yesterday's power output d)9 times yesterday's power ...
October 17, 2007

Physics
A force of 20 N is applied horizontally to a 1 kg mass on a level surface. The coefficient of friction is .2. if the mass is moved a distance of 5m what is the change in KE? W= change in Ke Fd= Change in KE (20)(5)=Change in Ke 200 J =change in Ke But the thing is how would I ...
October 17, 2007

Physics
A 1000kg car accelerates from 0 to 25m/s in 8s. What is the average power delivered by the engine? (1hp=746W) P=W/t p=Fd/t P=Fv p=mav =1000(25/8)(25) =78125W which is about 104.725 hp Is this correct?
October 17, 2007

Physics
A ball falls from the top of a building . through the air(air resistance is present) to the ground below. How does the KE just before hitting the ground compare to the PE at the top of the building? Isn't KE and PE equal to each other in this situation? Since I believe ...
October 17, 2007

Physics
What work is required to stretch a spring of spring constant 500N/m from x1=.2m to x2=.25m? Assume the unstreched position is at x=0. W=Fd so w=(500)(.25-.2) =500(.05) =25J is this correct? Calculate the work required to compress an initially uncompressed spring with a spring ...
October 17, 2007

Physics
If your last electric bill for sept. was \$105. If the average price is 6.5 cents per kw, how many kw did your household use in September? 1kw/.065 = x/\$105 .065x=105 x=1615.38 kw is this correct? How many Joules is that? I know that 1W =1Joule/second 1kw=1000W so 1615.38kw /...
October 17, 2007

Physics
A 15 N force is needed to move an object with constant velocity of 5 m/s. What power must be delivered to the object by the force? I konw that P=W/t and W=Fd But other than that I am confused . I am not sure how i would solve this problem.
October 16, 2007

Physics
A wooden block is moving on a rough level surface. It originally has 25J of kinetic energy. If the friction force acting on it is a constant 1N how far will it slide before comming to a stop? KE=F_f 1/2mv^2=F_n (meu) but the problem i run into is that meu and the mass isn'...
October 16, 2007

Physics
A 50kg skier pushes off the top of a hill with an initial speed of 5m/s. Neglect friction. How fast will he be moving after dropping 20m in elevation? I was wondering if i did this problem correct. PE + KE_f = KE_i mgh +1/2mv_f^2 =1/2mv_i^2 50(10)(20) + 1/2 (50)v_f^2 = 1/2(50...
October 16, 2007

Physics
A 50kg skier starts from rest from the top of a 100m slope. What is the speed of hte skier on reaching the bottom of the slope? Neglect friction. would i do this: =PE + KE =mgh +1/2mv^2 =50(10)(100) + 1/2 (50)v^2 =50000 +25v^2 =2000 =v^2 44.7m/s =v Is this correct? Thank in ...
October 16, 2007

english
what is cultural blindness
September 26, 2007

MATH/GEOMETRY!
HElp me !!!!!!! Malia told Lucia that she had figured out a pattern for computing the number of 3-letter names for any plane if she knew how many letters were named on the plane. For example, if there were four points, there were 4x 3x 2x 1 names possible. lucia said this ...
September 17, 2007

Algebra 1
HOW DO U TABLES,GRAPHS,MAPPING DIAGRAM?
September 10, 2007

English
In An American Childhood how does Annie Dillard reference life or death through the waterfall scene on page 150
September 8, 2007

math
Line L contains the points given in the table below. If the slope of line m is 1/3 the slope of line L what are three points that could be on line m? x 1 2 3 y -7 5 17 A.(1,-2),(2,10),(3,22) B.(1,-7),(2,3),(3,1) C.(1,-7),(2,2),(3,6) D.(1,-7),(2,2),(3,22)
August 27, 2007

Algebra
: if the quotient 3m^2 +15m / m^2 divided by 30/ m^2 + 5m is simplified to lowest terms, which of the following is the denominator of the resulting expression? the options are 10 30m^2 m^2 +5m or m^2( m+5) 10, with the restriction that m cannot be zero.
July 25, 2007

algebra 1 I NEED HELP!!
the bottom of a 25-foot ladder is placed 7 feet from a wall. How far will the ladder reach up? Since the ladder, wall, and ground form a right triangle, you can use this formula: A squared + B squared = C squared A = 7 feet C = 25 feet B = distance the ladder will reach 49 + B...
July 16, 2007

You work in the Human Resources department of your organization. You have been charged with recruiting a manager for a department within the Services division. The Vice-President of the Services division stresses to you that "This department hasn’t had a good manager...
May 22, 2007

Chemistry- acids and bases
Given the following neutralization raction: HCO3^- + OH^- <=> CO2[over]3^- + H2O a. label the conjugate acid-base pairs in this system b. is the forward or reverse reaction favored? Explain. Write net ionic equations that represent the following ractions: a. the ...
May 16, 2007

chemistry
Okay, so apparently ASA and FeCl3 form a violet complex and FeCl3 forms with phenol groups to make purple. Looking at the structures of ASA and salicylic acid, only salicylic acid has the phenol group. The thing is, salicylic acid is supposed to be an impurity in the ...
April 29, 2007

culteral diversity
The creation of minority group status for Mexican Americans reflected the dynamics of
April 19, 2007

algebra
graph y=4
April 10, 2007

Calculus, antiderivatives
A student accelerates from rest at a rate of 3 miles/min^2. How far will the car have traveled at the moment it reaches a velocity of 65 miles/60 min? a(t) = 3 miles/min^2 so v(t) = 3t + k miles/min but when t=0, v=0 so k=0 then v(t)=3t d(t) = 3/2 t^2 + c but when t=0 d, the ...
April 5, 2007

analogies
Whilwind, breeze: Downpour is to ?? The answer starts with scr,spr,str,and thr Sprinkle? Spray? Stream? You could try the on-line Rogets Thesaurus, type thesaurus into google. rain, mist, drizzle
April 3, 2007

World History
What are some modern examples of cultural blending in art? Consider music, literature, painting etc.. I can't find any info for this topic and I have to write a 1 page report. Possibly one of these artists would make a good topic: Frieda Kahlo http://www.google.com/search?...
March 25, 2007

algebra PLZ HELP!!!
y= 9/11x-17 9x-10y=179 You need to use parentheses to tell us what the problem is. Is equation 1, y = 9/(11x-17) or is it y = (9/11)x - 17? y= 9/11x-17 9x-10y=179 Rewrite them as 11 y - 9 x = -187 and -10 y + 9x = 179 Add the last two and you get y = -8 Substitute in any ...
February 23, 2007

MATH! HELP!!!
I am putting < for the square root abbreviation. I don't know how to use it on my comp. 3<99-2<44-6<11=? For Further Reading On a graphing calculator, the carrot symbol is used to show exponents. that’s what I used here. Solve your exponents first: 3^99, ...
February 22, 2007

Math
I am putting < for the square root abbreviation. I don't know how to use it on my comp. 3<99-2<44-6<11=? On a graphing calculator, the carrot symbol is used to show exponents. that’s what I used here. Solve your exponents first: 3^99, then 2^44, then 6^11 ...
February 22, 2007

solve the system using substitution {x+2y=11 {3x+2y=13 i just told u this one
February 22, 2007

solve the system using substitution {x+2y=11 {3x+2y=13 i just told you how to do the other one; it's the same exact method. solve for x and y. you get: x=-2y+11 and y=(-1/2x)+(11/2). then plug them both back into the original equation (either one, it doesn't matter); ...
February 22, 2007

i really, really, really need help
what coordinate point is the solution to the system? {3x+2y=8 {x-y=1 (2,1) please don't think i just made that up, it's correct. you have to use substitution, when you do solve for x and y, you get: x= y+1 and y=x-1, plug in y for 3x+2y=8 and you get: y=1, then plug in...
February 22, 2007

algebra 1
what coordinate point is the solution to the system? {3x+2y=8 {x-y=1 y=x-1 so 3x+2(x-1)=8 3x+2x-2=8 5x-2=8 5x=10 - - 5 5 x=2 Then 2-y=1 -2 -2 -y=-1 y=1 Well, to cut the crap the answer is (2,1)
February 22, 2007

egypt mummification
um guys i just wanna know what the plugged eye sockets with
February 8, 2007

spelling
What is boil soil :: goat?
January 16, 2007

Maths test
A store gives a staff discount of one fifth. How much would a member of staff pay for: a) a camera with a retail price of £215? just do 215 divided by 1/5 (0.20) and you'll have the amount in "pounds" (i think that's what that sign stands for)....if you...
December 5, 2006

Inter. Algebra
square root sign 2x+3 - square root sign x-2 =2 In my head, I worked it as x=3. I did that because only sqr roots that are rational integers can be subtracted to give a whole number. Now, analytic method. I have no idea, I dont see a simple method in ordinary algebra. how do ...
December 2, 2006

Inter. Algebra
Count Iblis how do you simplify 3square root sign with this underneath (3x squared y) to the third power? "3 square root sign" probably means "cube root", in which case [(3 x^2y)^3]^(1/3) = 3 x^2 y The cube root of any quantity x can be written x^(1/3)
December 2, 2006

Inter. Algebra
Count Iblis what is the answer to 2 square root sign 18x? The instructions say to simplify or reduce. 2*(18x)1/2= 2*(9*2)1/2= 2*3(2)1/2= 6*(2)1/2 If you can leave it in this form, the above is the way to end. If you are to continue to a final answer, then, finish by 6*1.414 =8...
December 2, 2006

Inter. Algebra
Another problem plz help Count Iblis. How do you solve 5/x+2 + 2x/x squared - 4= 3/x-2? 5/x+2 + 2x/x squared - 4= 3/x-2 You write the term: 2x/x squared as 2/x the equation becomes: 5/x+2 + 2/x - 4= 3/x-2 4/x = 0 This equation has no solutions. It is only satisfied in the ...
December 2, 2006

Inter. Algebra
Simplify 2i to the 5th power? (2i)^5 = 2^5 * i^4 * i = 32 (-1)^2 * i = 32 i
December 2, 2006

Inter. Algebra
what is the answer to 2i to the 5th power? i^2 = -1 --> i^4 = 1 ---> i^5 = i (2i)^5 = 32 i thanks for the info!
December 2, 2006

Inter. Algebra
can you simplify 12x squared y cubed?
December 2, 2006

Inter. Algebra
what is the answer to 2 square root of 18x? Do you mean 2*(18x)1/2? What does it equal. What are we to do with the problem? DrBob222, My problem states 2 square root sign & 18x underneth it. If you could help me with this problem I'd really appreciate it. It must be equal ...
December 2, 2006

Inter. Algebra
what is the answer to 12x squared y cubed /2xy squared +6xy * y squared +6y+9 /3y cubed +9y squared? You have not written an equation, only an algebraic function, with two variables. You need to add parentheses to clarify the order of operations. There is no "answer"...
December 2, 2006

Inter. Algebra
how do you foil 12x squared y cubed?
December 2, 2006

story board???
okay, so what exactly is a story board? I used to assign these. Here were the directions: 1. Divide a page into six sections (like the little frames in a cartoon series in the newspaper). Students usually had two rows or three sections. 2. Decide on the six main actions in a ...
November 21, 2006

World History
What was the reason for the downfall of the Han Dynasty and The Roman Empire? Was is partially invasion from barbarians? Han Dynasty: http://www.google.com/search?q=han+dynasty+downfall&ie=utf-8&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a Roman Empire: http://www....
November 21, 2006

social studies
person whogives to a business or project hopeing to make a profit investor
November 13, 2006

Financial Management
Year Cash Flow(A) Cash Flow (B) 0 -307,206 -27,651 1 14,950 8,726 2 32,391 13,901 3 29,232 9,222 4 390,590 13,140 15% rate of return. what is the payback period for Period A and B.
November 5, 2006

math
I'm having some troubles with these. Thanks in advance. If a>0 find the minimum value. If a<0 find the maximum value. 1. y=-x²+2x+5 2. y=-2x²-3x+4 These are functions for parabolas, so f(x)=ax²+bx+c when a does not equal 0 In both your examples, the &...
October 31, 2006

HELP WIT A QUESTION
the settlers of jamestown saved their colony by planting?
October 18, 2006

word unscramble
louvcarese (2 words) funceelni dearpilshe stiche gametannem thanimoreolans (2 words) ginlapnn
September 28, 2006

physics
At a construction site, a brick fell and hit the ground at 24m/s a) from what height did the brick fall? b) how long was it falling? for a) i got 29.387m and for b) I got 2.448s I got a) by using v^2=v0^2 +2a(x-x0) for b) I used v=v0+at Did I do this problem correctly? If we ...
September 19, 2006

Math
Can someone please help me with an algebra problem? -|4-8b|=12 I really get confused with the absolute value symbols and a negative sign outside of them. Don't worry about it; it does tend to be a bit confusing. I'll explain the difference between inside and outside ...
September 14, 2006

bay and penninsula
What is the difference between a bay and a penninsula? A bay is a body of water -- smaller than a sea or ocean or gulf -- that is not completely surrounded by land. San Francisco Bay is one good example. A peninsula is a land formation that is surrounded on all but one side by...
September 5, 2006

unscrambling word
mTHAMEAICST
June 14, 2005

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