Friday

May 6, 2016
Total # Posts: 3,426

**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*

**Physics **

Electromagnetic waves can form standing waves. In a standing wave pattern formed from microwaves, the distance between a node and an adjacent antinode is 0.63 cm. What is the microwave frequency? any help is much appreciated
*November 23, 2012*

**physics**

Linearly polarized light is incident on a piece of polarizing material. What is the ratio of the transmitted light intensity to the incident light intensity when the angle between the transmission axis and the incident electric field is (a) 30° and (b) 71°? Help! :(
*November 23, 2012*

**physics**

An object is located 16.8 cm in front of a convex mirror, the image being 11.5 cm behind the mirror. A second object, twice as tall as the first one, is placed in front of the mirror, but at a different location. The image of this second object has the same height as the other...
*November 23, 2012*

**Physics**

The two blocks in the figure below, m1 = 1.2 kg and m2 = 4.8, are connected by a massless rope that passes over a pulley. The pulley is 12 cm in diameter and has a mass of 2.0 kg. As the pulley turns, friction at the axle exerts a torque of magnitude 0.38 N·m. If the ...
*November 21, 2012*

**Civics**

1.The constitution grants the federal courts ____ in several different kinds of court cases. This gives them the authority to hear and decide cases properly brought before them. 2. The lowest federal courts are trial courts, which have ___, the authority to hear and decide a ...
*November 20, 2012*

**physics**

An open train car, with a mass of 2070 kg, coasts along a horizontal track at the speed 2.31 m/s. The car passes under a loading chute and, as it does so, gravel falls vertically into it for 3.25 s at the rate of 491 kg/s. What is the car's speed after the loading is ...
*November 19, 2012*

**Physics**

dude I have no idea what you just typed.. can you please clarify what all the variables you used stand for?
*November 19, 2012*

**Physics **

A thrill-seeking cat with mass 4.00 kg is attached by a harness to an ideal spring of negligible mass and oscillates vertically in SHM. The amplitude is 0.050 m, and at the highest point of the motion the spring has its natural unstretched length. Calculate the elastic ...
*November 19, 2012*

**Physics**

A plane drops a bomb from an altitude of 10,000m. a. Determine the time the bomb is in the air. b. Determine the velocity the bomb would have right before it hits the ground. c. Before the bomb is launched the plane has a horizontal velocity of 92m/s. Determine the distance ...
*November 19, 2012*

**Chemistry Help**

Write the net ionic equation for the reaction of calcium nitrate and sodium phosphate
*November 14, 2012*

**Chemistry Help**

If you mixed 10.0 mL of calcium nitrate and sodium phosphate, both 0.250M,which of the two would be the limiting reactant?
*November 14, 2012*

**Physics**

G: Vi = 50m/s Degree = 37 U: Vy, Vx, Dy, Dx, T E: Vy = Vi(Sin(θ)), Vx = Vi(Cos(θ), Dy = Vy(1/2)(t) + 1/2(a)(1/2t^2) Dx = Vx(t) (Because the speed is constant) t = 6.14 s, h = 46.2, Δx = 245.2 m
*November 13, 2012*

**chemistry (molecular calculations)**

If you had 78.2 grams of K, how much oxygen is needed to convert it all to K2O?
*November 13, 2012*

**math**

A material has a half-life of 12 hours. If initially there are 4 grams of the material, how much is present after 8 hours? I know the answer is 8/3, but how would you solve this using calculus? please help.
*November 11, 2012*

**Math**

Is this correct? If one card is drawn from a regular deck of cards,what is the probability the card will not be an ace? 1/13 is the probability
*November 9, 2012*

** Math**

If one card is drawn from a deck of cards,what is the probability the card will not be an ace? I think the answer is 1/13. Am I correct???
*November 9, 2012*

**Geography**

Is this correct? 1. The closest ocean to Mongolia is the Pacific Ocean. 2. The capital of the island nation that has the Sea of japan as its western border is Tokyo, Japan. Thank You
*November 9, 2012*

**physics**

A car travels in a straight line for 4.8 h at a constant speed of 57 km/h . What is its acceleration? Answer in units of m/s
*November 8, 2012*

**Physics Help**

Two compressible solids are formed into spheres of the same size. The bulk modulus of sphere two is twice as large as the bulk modulus of sphere one. You now increase the pressure on both spheres by the same amount. As a result of the increased pressure, how is the change in ...
*November 7, 2012*

**Implicit differentiation **

implicit differentiation of x^3y^2-5x^2y+x=1
*November 7, 2012*

**Chemistry**

7.0
*November 3, 2012*

**calculus**

This is the problem that I got. I thought of that too. I think that it might just be a type? x is probably suppose to be h...
*November 3, 2012*

**calculus**

Given: y^2+h^2=1 Find h as a function of y. If expression for dy/dx includes h, substitute the expression in terms of y for h. Write dy/dx in terms of y only. Show that x=[(1+sqrt(1-y^2))/y]-sqrt(1-y^2) satisfies the differential equation you found to prove this equation ...
*November 3, 2012*

**calculus**

Given: y^2+h^2=1 Find h as a function of y. If expression for dy/dx includes h, substitute the expression in terms of y for h. Write dy/dx in terms of y only. Show that x=[(1+sqrt(1-y^2))/y]-sqrt(1-y^2) satisfies the differential equation you found to prove this equation ...
*November 3, 2012*

**Chem**

The following substances undergo complete combustion in a bomb calorimeter. The calorimeter assembly has a heat capacity of 5.136 ^ C. In each case, what is the final temperature if the initial water temperature is 22.37^ C? 0.3268g caffeine, C8H10N4 (heat of combustion = -...
*October 29, 2012*

**College Chemistry**

Calculate the heat in joules needed to warm 225g of water from 88.0 degrees Celsius to its boiling point 100.0 degrees Celsius
*October 24, 2012*

**Biology**

1)Animal cells prefer to be in isotonic solution, while plant cells prefer to be in hypotonic solution. Explain what this means and why it is so. 2.) In terms of Gibbs free energy, what does “unstable” mean? Also, give at least two additional ways to say that a ...
*October 24, 2012*

**physics**

A box slides down a plane 8 m long that is inclined at an angle of 30 degrees with the horizontal. If the box starts from rest and u = 0.25, find a.) the acceleration of the box, b.) it's velocity at the bottom of the plane, and c.) the time required for it to reach the ...
*October 23, 2012*

**Math**

Sare estimated 32x45 by using 30x40. How could Sara make a more accurate estimate?
*October 22, 2012*