Thursday
October 2, 2014

Posts by Alex


Total # Posts: 2,610

Physics
Black Holes are suspected when a visible star is being noticeably pulled by an invisible partner that is more than 3 times as massive as the Sun. A red giant star is accelerated in a linear direction by gravity at 0.075 m/s2 towards an object that is 9.4 x1010 m away. a) What ...
January 11, 2013

Physics
The International Space Station is 370 km above the Earth's surface (Re = 6378 km, Me = 5.98 x 10^24 kg). What is the linear velocity of the space station in m/s
January 11, 2013

chemistry
The solubility of strontium oxide, SrO, in water is 22.8 g per 100 mL at 100 °C and 0.69 g per 100 mL at 30 °C. Is the dissolving of strontium oxide in water an endothermic or exothermic process?
January 10, 2013

math PLEASE HELP IM STUCK!!!
Admissions to a concert cost $45. A vendor sells t-shirts for $12 each. What is the maximum number of t-shirts you can buy?
January 10, 2013

math
admissions to a concerto cost $45. A vendor sells t-shirts for $12. You have $90. What is the maximum number of t-shirts you can buy?
January 10, 2013

science
how much potential energy did the object have before it fell?
January 9, 2013

science
a cart was pulled for a distance of 1 kilometer and the amount of work accomplished equal 40.000 joules. with what force was the work accomplished?
January 9, 2013

science
a cart was pulled for a distance of 1 kilometer and the amount of work accomplished equal 40.000 joules. with what force was the work accomplished?
January 9, 2013

physical science
push a box across a table with a force of 5 newtons and the box moves 0.5 meter. how much work has been accomplished?
January 9, 2013

math
I was confused somewhat more difficult
January 8, 2013

math
solve each system by elimination x+y=10 x-y=2
January 8, 2013

math
1. y=xt1 2x+y=7 2. x=y-2 3x-y=6 3. y=2xt3 5x-y=-3
January 8, 2013

algebra
solve each system by substitution 1. 6x-3y=-33 2xty=-1 2. 2x-y=7 3x-2y=10 3. 4x=8y 2x+5y=27
January 8, 2013

physical science
Mike jogs east at a rate of 4 mph. The wind is blowing west at 1 mph. What is Mike's velocity?
January 8, 2013

algebra
supose you bought eight oranges and one grapefruit for a total of $4.60. later day, you bought six oranges and three grapefruits for a total of $4.80. what is the price of each type of fruit?
January 8, 2013

algebra 2
please help me
January 8, 2013

Algebra 2
Write a polynomial function in standard form with the given zeros: x=2,-2,4
January 7, 2013

Physis
a 2kg mass is hung from a tree and is released. Using the nodes on the graph, sketch the general shape of the vertical position of the mass versus time
January 4, 2013

grammar
1is correct
January 3, 2013

Physics
A coin is placed on an old record turntable which rotates at 78 rpm. The coefficient of friction between the record and the coin is 0.17. a) What is the angular speed of record in radians/s? b) At what distance (m) from the center will the coin begin to slide off the record? c...
January 3, 2013

Physics
Thanks
January 3, 2013

Physics
A toy plane of mass 0.624 kg is flown in a circle when attached to a string. The plane moves around the circle with a rotational speed of 8.09 rpm. The length of the string is 2.60 m. What is the tangential velocity, v, of the plane? .
January 3, 2013

Physics
A student puts on a Dresden Dolls disc in her cd player which spins at 1800 revolutions per minute. A compact disc has a mass of about 0.016 kg and a radius of 6.0 cm. a) What is the period of rotation in seconds? b) What is the frequency of the rotating disc? c) What is the ...
January 3, 2013

Physics
I was not taught how to do this
January 3, 2013

Physics
c) A penny sits 12 cm from the center of a record turning at 33 1/3 rpm. What is the tangential speed in m/s? d) A mass spins with a tangential speed of 1.2 m/s on the end of a string which is 0.75m long. What is the period of the rotation in seconds?
January 3, 2013

Physics
On August 12, 2005 the Mars Reconnaissance Orbiter (MRO) was launched from Earth and reached Mars on March 10, 2006. The orbiter is in roughly circular orbit about 390 km above the martian surface. Mars has a radius of 3396 km and a mass of 0.642 x 1024 kg (6.42E23 kg). b) ...
January 3, 2013

5th grade math (word problems)
pennies! Thanks Ms. Sue
January 3, 2013

5th grade math (word problems)
I'm not sure how to solve the following problem: If you divide 1/10 of a dollar into parts that are each 1/100 of a dollar, how many parts are there? What are they called? To solve, would part of the answer be that i would have 10 parts of 1/100 (because I divide 100 by 10...
January 3, 2013

Math
P=2l+2w P-2l=2w (p-2l)/2=w
January 3, 2013

Physics
A coin is placed on an old record turntable which rotates at 78 rpm. The coefficient of friction between the record and the coin is 0.17. a) What is the angular speed of record in radians/s? b) At what distance (m) from the center will the coin begin to slide off the record? c...
January 3, 2013

Physics
Thanks
January 3, 2013

Physics
A toy plane of mass 0.624 kg is flown in a circle when attached to a string. The plane moves around the circle with a rotational speed of 8.09 rpm. The length of the string is 2.60 m. What is the tension in the string?
January 3, 2013

Physics
A toy plane of mass 0.624 kg is flown in a circle when attached to a string. The plane moves around the circle with a rotational speed of 8.09 rpm. The length of the string is 2.60 m. What is the tangential velocity, v, of the plane? .
January 3, 2013

Physics
A student puts on a Dresden Dolls disc in her cd player which spins at 1800 revolutions per minute. A compact disc has a mass of about 0.016 kg and a radius of 6.0 cm. a) What is the period of rotation in seconds? b) What is the frequency of the rotating disc? c) What is the ...
January 3, 2013

Physics
c) A penny sits 12 cm from the center of a record turning at 33 1/3 rpm. What is the tangential speed in m/s? d) A mass spins with a tangential speed of 1.2 m/s on the end of a string which is 0.75m long. What is the period of the rotation in seconds?
January 3, 2013

Physics
On August 12, 2005 the Mars Reconnaissance Orbiter (MRO) was launched from Earth and reached Mars on March 10, 2006. The orbiter is in roughly circular orbit about 390 km above the martian surface. Mars has a radius of 3396 km and a mass of 0.642 x 1024 kg (6.42E23 kg). b) ...
January 3, 2013

Algebra
Are you in Algebra 2?
January 2, 2013

Art
How can lines in a painting lead your eyes
January 1, 2013

Math problem solving investigation: guess and chec
The area of each square is twice the area of the next smaller square drawn in it. If the area of the smallest square is 3 square centimeters, what is the area of the largest square
December 29, 2012

english
Which of the following sentences is correctly punctuated A. The sea calmed; but no boats, left shore. B. The sea, calmed, but no boats, left shore. C. The sea calmed, but no boats left shore. D. The sea calmed but no boats left shore.
December 22, 2012

Physics
Kang and Kodos orbit the Earth in a spaceship 20,000 km above Springfield.the period of their orbit (hours) is 11.8 and findthe speed (m/s) their spacecraft travels. b) Speed of spacecraft in meters per second m/s .
December 20, 2012

Physics
How many times further from the Sun than the Earth is an asteroid with an average orbital period of 7.43 years? (HINT: Let the distance to the Earth be R=1 AU)
December 20, 2012

Physics
Use Kepler's Laws and data about the Moon to determine the orbital period (hours) of a satellite that is 17512 km above the SURFACE of the Earth. HINT: How does the radius of the Earth affect the problem?
December 20, 2012

Physics
Kang and Kodos orbit the Earth in a spaceship 20,000 km above Springfield.the period of their orbit (hours) is 11.8 and findthe speed (m/s) their spacecraft travels. b) Speed of spacecraft in meters per second m/s .
December 20, 2012

Physics
Thanks SOOO much
December 20, 2012

Physics
The gravitational force between two asteroids 1200 km apart is 8400 N. Find the following changes in gravity (do not write units) a) What is the force between them if the distance is 600 km?
December 20, 2012

physical science
1-Patty climbs a tree. While sitting on a branch, she drops a leaf and an acorn at the same time. What would happen?
December 18, 2012

history
World War I
December 18, 2012

history
the war's impact
December 18, 2012

history
the war's impact united states
December 18, 2012

history
what increased the cost of living after the war?
December 18, 2012

calculus
Determine the largest rectangle that can be inscribed inside the cavities of the two curves: y = –2(x – 6)2 & y = 6x2 –12*Tx – 128 + 6*T2
December 16, 2012

calculus
A 6 m3 box with a perfect triangle base and lid and 3 rectangular walls is to be constructed from 2 materials. The cost to make the base 1$/ft2 and that for the lid and walls is 4/2 $/ft2. What dimensions will result in the most cost-effective construction?
December 16, 2012

Biology
Eukaryotic chromatin can be chemically modified in several ways. List at least three modifications and describe the effect of these modifications.
December 15, 2012

Biology
If you were to examine the mature mRNA that comes from a certain human gene, and then line it up to the actual DNA sequence of that same gene, you would see many differences. What would these differences be and where do they come from?
December 15, 2012

Physics
A 59-kg person on skis starts from rest down a hill sloped at 36° from the horizontal. The coefficient of friction between the skis and the snow is 0.16. After the skier had been moving for 5.0 s, the friction of the snow suddenly increased and made the net force on the ...
December 15, 2012

physical science
A 3000-kg car bumps into a stationary, 5000-kg truck. The velocity of the car before the collision was +4 m/s and -1 m/s after the collision. What is the velocity of the truck after the collision?
December 15, 2012

physics
Why might it be hard for the firefighter to hold the hose steady when the water gushes out of the hose? Think about the law of conservation of momentum.
December 15, 2012

math
if a tree in a 1/2 inch scale drawing is 11 inches tall, how tall is the actual tree?
December 15, 2012

Chemistry
babol, for diffraction we need a wave, and according to de Broglie (and later experiments) any matter behave like a waves with different lengths ( depends on their energy). So actually we make a diffraction of electrons (as a waves) on a Mo surface.
December 14, 2012

Chemistry
ok, b) eV=E To get electrons behave like a waves with the same lenght as 0.561A, we need to give them some impulse p according to de Broglie eq. and E = p^2/2m..
December 14, 2012

Chemistry
and b) is a voltage, needed to accelerate electrons to get the same.. :)
December 14, 2012

EPCC
how to calculate the heat (kJ) released to thesurroundings when a 23.0 g of HCL if formed, from a CH4 + Cl2=CHCl3+3HCL
December 13, 2012

5th grade math (word problems)
Could you explain why you divided 25 by 3/5?
December 12, 2012

5th grade math (word problems)
I didn't see an answer from yesterday, so resending. Also, is there a website to explain how to solve word problems - like key phrases to look for (ex: 'in all' - add; 'what's left' - subtraction)? Here's question from yesterday: sorry,but I don'...
December 12, 2012

Chemistry - solubility, not "Methode Champenoise"
Is CO2 soluble in ethanol? I know that CO2 is nonpolar, so that means it's soluble in nonpolar solvents, but CO2 is soluble in H2O. H2O is polar. Also, if CO2 were obeying Henry's Law, would it be soluble in ethanol at a high pressure?
December 11, 2012

chemistry
In the "Methode Champenoise," grape juice is fermented in a wine bottle to produce sparkling wine. The reaction is given below. C6H12O6(aq)--> 2 C2H5OH(aq) + 2 CO2(g) Fermentation of 746 mL grape juice (density = 1.0 g/cm3) is allowed to take place in a bottle ...
December 11, 2012

5th grade math (word problems)
sorry,but I don't understand word problems - like what formula/expression to use. Here's the 1st problem: Rob practiced 3/5 of his music in 25minutes. About how long does it take to practice all of his music? I know that Rob has 2/5 left of music to practice. So, do I ...
December 11, 2012

Chemistry
In the "Methode Champenoise," grape juice is fermented in a wine bottle to produce sparkling wine. The reaction is given below. C6H12O6(aq)--> 2 C2H5OH(aq) + 2 CO2(g) Fermentation of 746 mL grape juice (density = 1.0 g/cm3) is allowed to take place in a bottle ...
December 11, 2012

math
Thank you very much. This problem was giving me too much stress.
December 10, 2012

math
Find the value of the function y=sqrt(x+1)+sin(x)-0.5, correct to 3 decimal places, when x=0.05 without the use of a calculator.
December 10, 2012

Chemistry
In the "Methode Champenoise," grape juice is fermented in a wine bottle to produce sparkling wine. The reaction is given below. C6H12O6(aq)--> 2 C2H5OH(aq) + 2 CO2(g) Fermentation of 746 mL grape juice (density = 1.0 g/cm3) is allowed to take place in a bottle ...
December 9, 2012

5th grade math (dividing fractions)
Sorry Khan, I was trying to say that I needed to solve for x in the problem: 3 divided by x over 9 = 5 and two fifths. . Steve, thanks for the answer. But, I'm still not sure how you solved for x after getting 27/x= 27/5. Did you multiply both sides by 1/27 to get x by ...
December 9, 2012

5th grade math (dividing fractions)
Hi.. I need help figuring out this problem, sovling for x: 3 divided by x/9 = 5 and 2/5 I was able to solve: x divided by 3/4 = 6 by multiplying 6 x 3/4 = 4 1/2. Just not sure how to solve the first problem. If I change 5 2/5 into mixed number,I still don't know what to do...
December 9, 2012

Fourth grade science
Students are conducting an investigation that tests the force of a magnet by using one magnet to repel a second magnet. Which tool would be needed to measure the distance the second magnet moves? A thermometer,A spring scale, A ruler, or A compass
December 7, 2012

physics
A nearsighted person has a far point located only 200 cm from his eyes. Determine the focal length of contact lenses that will enable him to see distant objects clearly. does anyone have any suggestion on how to tackle this problem?
December 6, 2012

9th garde math
Write an equation for the line with points (4,5) and (6,9). Please explain.
December 5, 2012

Geography
Is this correct? Hawaii and the Florida Keys are the only 2 states that are located south of the 25 degrees N latitude line?
December 5, 2012

Math
The kindergarten has a box of blocks.Some blocks are red,some yellow and some are blue.1/2 of the blocks are red,1/4 of the blocks are yellow and 24 of the blocks are blue.How many blocks are in the box?
December 5, 2012

science
at what altitide(height above earth's surface) would temperatures be 22 degrees C?
December 5, 2012

Algebra
You need to set up a system of equations. No one knows how many of each type of bill there is. Let t=twenties and f=fifties. t+f=36 20t+50f=1170 -20(t+f=36)=-20t+-20f=-720 20t+50f=1170 30f=450 f=15 t+15=36 -15 -15 t=21
December 5, 2012

algebra-NOW PLEASE
A boat is traveling in a river with a current that has a speed of 1.5 km/h. In one hour, the boat can travel twice the distance downstream as it can travel upstream. What is the boat's speed in still water?
December 4, 2012

Algebra
Simple. 70=7w
December 4, 2012

Algebra
[4(5)+-4]raised to 2nd (20+-4)raised to 2nd 16 raised to 2nd 256 is the answer
December 4, 2012

Trig
A population of animals oscillates annually from a low of 1300 on January 1st to a high of 2200 on July 1st, and back to a low of 1300 on the following January. Assume that the population is well-approximated by a sine or a cosine function. a. Find a formula for the population...
December 3, 2012

Chemistry Help
T=PV/nR P=0.96 V=0.045 n=0.002 g/mol R=0.082057
December 2, 2012

Chemistry Help
Using the accurate concentration that you measured in Part A (which is 14.77 ml), calculate the mass of HCl (in grams) present in a 15.00-mL sample of the acid solution, using proper dimensional analysis
December 2, 2012

College Chemistry
Using the accurate concentration that you measured in Part A (which is 14.77 ml), calculate the mass of HCl (in grams) present in a 15.00-mL sample of the acid solution, using proper dimensional analysis
December 2, 2012

Math (Calculus)
Use implicit differentiation to find the slope of the tangent line to the curve y/(x–9y)=x^6–2 at the point (1,-1/-8). Can someone please help me? I dont understand
November 30, 2012

MAth t
i d k but if youre in math course 7th grade im in too and u dont answer if u dont kno it cuzz this is one of the challenege questions teacher just mark as extra credit if u want but it really doesnt count
November 30, 2012

Math (Calculus)
A spherical snowball is melting in such a way that its diameter is decreasing at rate of 0.3 cm/min. At what rate is the volume of the snowball decreasing when the diameter is 10 cm. Can someone help & explain how to solve this question? Please.
November 29, 2012

math
Estimate a 15% tip on a taxi ride that costs $23.25.
November 29, 2012

math
72 is what percent of 480? Write and solve an equation to solve the problem
November 29, 2012

math
Jessica bought a computer for $325 and had to pay 6% sales tax. What was the total cost of Jessica’s computer?
November 29, 2012

Steveeee help plz
What is the area is square units o the region under the curve of the function f(x)=4, on the interveral from x=-1 to x=3
November 28, 2012

Steve help pleaseeeee
Two promotional stands are to be placed in an ellipse shaped room. One at each foci and are 3 units from center. If the room is 8 units wide what is the length
November 28, 2012

math
y1= sin (x) y2= (tanx) It is graphed in the interval [0, pi/2] find the integral
November 28, 2012

calculus
y1= sin (x) y2= (tanx) It is graphed in the interval [0, pi/2] find the integral
November 28, 2012

5th grade Language Arts
Thanks Ms. Sue! I have other sentences I would like to try to get right. 1. Mr. Morton, the best reading teacher in the world, taught me sentence structure. Complex: Mr. Morton taught me sentence structure = indep & best reading teacher in the world = dep 2. I left early so ...
November 26, 2012

5th grade Language Arts
I need help classifying sentences (compound, complex, compound-complex). Here's the sentence: I got in trouble so I can't go to the party, but it would have been fun. I answered it was complex which I got wrong.
November 26, 2012

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