Friday

September 4, 2015
Total # Posts: 522

**Chemistry**

A 25.40 g sample of water containing tritium,(3/1)H , emits 1450 beta particles per second. Tritium is a weak beta emitter, with a half-life of 12.3 yr. What fraction of all the hydrogen in the water sample is tritium?
*February 13, 2012*

**Chemistry**

A 50.6 mg sample of sodium perchlorate contains radioactive chlorine-36 (whose atomic mass is 36.0 amu). If 29.6% of the chlorine atoms in the sample are chlorine-36 and the remainder is naturally occurring nonradioactive chlorine atoms, how many disintegrations per second are...
*February 13, 2012*

**Chemistry**

Cobalt-60, which undergoes beta decay, has a half-life of 5.26 yr. How many beta particles are emitted in 190s by a 3.10mg sample of Co-60? What is the activity of the sample in Bq?
*February 13, 2012*

**geometry**

I need help to graph the circle 4x^2+4y^2+16x-32y+71=0 Graph the circle
*February 12, 2012*

**Chemistry**

Cobalt-60, which undergoes beta decay, has a half-life of 5.26 yr. How many beta particles are emitted in 190s by a 3.10mg sample of Co-60? What is the activity of the sample in Bq?
*February 12, 2012*

**Microbiology**

Please help me answer this question. Thanks a lots. Some Archaea have ATPases with different H+:ATP ratios. Assumes the delta Gp for ATP synthesis in one such organism is -518 mV. The minumum delta P required to generate ATP with a typical bacterial ATPase is about -173 mV. ...
*February 9, 2012*

**Math**

Solve each equation. 9n-3=7(n+3)+2n I got -24 is that right?
*February 8, 2012*

**Algebra II**

What is the simplified version of (2x^(-3)y^(2))^(-2) and (z^4)/(2z^3) Thanks!
*January 29, 2012*

**algebra**

what is 28 seconds over 2 minutes written in its simplest form
*January 28, 2012*

**APUSH**

how did huge industrial trusts develop in industries such as steel oil and banking, what was the effect on the economy?
*January 24, 2012*

**Physics**

A total of 8.0 joules of work is done when a constant horizontal force of 2.0 newtons to the left is used to push a 3.0 kilogram box across a counter top. Determine the total horizontal distance the box moves.
*January 16, 2012*

**ahsa math**

hey need help with this asap you are given 12 feet of fencing to build a cage how many different rectangle can you build? WHICH WOULD YIELD THE MAXIMUM AREA
*January 5, 2012*

**pre calc**

evaluate the trigonometric function of the given quadrantal angle. tan 1440° Evaluate without using ratios in reference triangle. sec 3π/4
*January 4, 2012*

**finance**

a.Project A Payback period Year 1 + Year 2 + Year 3 = $60,000 Year 4 + $20,000 Initial investment = $80,000 Payback=3 years + ($20,000 / 30,000) Payback =3.67 years Project B Payback period $50,000/ $15,000 = 3.33 years B. Project A CF0 = -$80,000; CF1= $15,000; CF2= $20,000; ...
*January 4, 2012*

**Chemistry**

What acid and what strong base would react in aqueous solution to produce the following salts in the formula equation? Write the balanced formula equation for each reaction. a) potassium perchlorate b) cesium nitrate c) calcium iodide I don't need just the answers, I'm...
*December 28, 2011*

**calculus 2**

what is the polar area between r=5sinx and r=5cosx
*December 7, 2011*

**calculus**

A metal chain weighs 30 lbs and is 10 feet long. How much work is required to lift one end of the chain to a height of 15 feet (so that the other end of the chain will be at a height of 5 feet)?
*December 1, 2011*

**psychology**

Suppose that you are dropping off at a large mall without money and merely wander around looking at stores and displays. Later, someone asks you were a particular store is located in the mall. The fact that you direct the person to the store indicates that ______________ has ...
*November 12, 2011*

**Math**

You are bending a wire to make a coat hanger. The length of the wire is 88 centimeters, and 20 centimeters are needed to make a hook hanger. The triangular portion of the hanger is an isosceles triangle. The length of one leg of this triangle is 3/5 the length of the base. ...
*November 1, 2011*

**Physics**

The wind exerts a force of 284 N North on a sailboat, while the water exerts a force of 132 N West on the sailboat. What is the magnitude of the net external force on the sailboat? Answer in units of N
*October 27, 2011*

**Physics**

The two cubes in the drawing are made from the same material. The radiant energy per second emitted by the small cube is 3.70 J/s. What is the energy emitted per second by the larger one?
*October 3, 2011*

**physics**

A car accelerates from rest at a constant rate of 2.2 m/s2 for 6.9 s. How far does the car travel in this time?
*October 3, 2011*

**Physics**

Well if you multiply the static and the kinetic friction and add gravity to it you get the minimum magnitude. PhD in Physics
*October 1, 2011*

**chemm**

find the density of ethyl alcohol if 80.0 cm^3 "weighs" 63.3g.
*September 27, 2011*

**chemistry**

find the density of ethyl alcohol if 80.0 cm^3 "weighs" 63.3g.
*September 27, 2011*

**physics**

509.7M
*September 25, 2011*

**Organic Chemistry**

What are the theoretical moles and grams obtainable when 53.9g of ethanol is dehydrated?
*September 7, 2011*

**Organic Chemistry**

What are the theoretical moles and grams obtainable when 53.9g of ethanol is dehydrated?
*September 7, 2011*

**Organic Chemistry**

What are the theoretical moles and grams obtainable when 53.9g of ethanol is dehydrated?
*September 7, 2011*

**chemistry (please help)**

Mass = Density x Volume M=1.11g/cm^3 x 26.5 liters Mass = 29.425 Kg
*September 6, 2011*

**Geometry**

m<RST =150, m<GST = x + 131, and m<RSG = x = 41. Find m<GST.
*August 29, 2011*

**algebra**

Who saw the brontosaurus enter the restaurant
*May 21, 2011*

**Biology**

True
*May 20, 2011*

**math Algebra I**

Perimeter of table top is 28 feet. The difference between 4 times the length and 3 times the wide is 21 feet. Find the dimension. (Use system of linear equations to solve.)
*May 13, 2011*

**social studies**

how geography influenced the expansion of greece?
*May 5, 2011*

**math**

what is 50% of 20
*April 28, 2011*

**math**

1 kg= g
*April 26, 2011*

**Essay evaluation**

Please grade my GMAT essay on 6 The author of the statement believes that the century old practice of using money in its physical form should be replaced by electronic accounts of credits and debits. Some people may argue that this practice is elitist and people of the lower ...
*April 18, 2011*

**Analysis of Argument**

Thank you for your help! :) Im not a native english speaker and havent written an essay . I would really like some inputs. :)
*April 16, 2011*

**Analysis of Argument**

Question: “According to a recent study, professional bodybuilders who used Train & Gain, a new protein supplement, over the course of three months experienced an increase in measured strength of up to 20%. Since Train & Gain is now available without prescription at all ...
*April 16, 2011*

**GMAT Essay- Analysis of issue**

In what ways can i improve this? more examples?
*April 16, 2011*

**GMAT Essay- Analysis of issue**

Please grade my essay on 6 Topic “Parents should not shoulder the full burden of their children’s college tuition. If university students are required to pay for at least a portion of their education, they will take their studies more seriously and, ultimately, ...
*April 16, 2011*

**GMAT Essay**

Thank you for your inputs :)
*April 15, 2011*

**GMAT Essay**

Hey All, Please rate my GMAT essay out of 6. The topic is “Of all the manifestations of power, restraint in the use of that power impresses people most.” Explain what you think this quotation means and discuss the extent to which you agree or disagree with it. ...
*April 15, 2011*

**Biology**

Need a more detailed picture of the sheep's pluck...lungs, trachea, and heart.
*April 12, 2011*

**Biology2**

Could you possibly give me a link to a more detailed picture? For example one that outlines each lobe and depicts more of the internal anatomy of the sheep's lung.
*April 12, 2011*

**Biology**

Where can a find a picture of a sheep's lung with labeled parts?
*April 12, 2011*

**science**

what was the altitude in degrees of the moon on 3/18/11
*March 21, 2011*

**chemistry**

what is the entropy change that occurs when 500g of water ice melts at 0 degrees celsius and 1 atm. the heat of fusin for water ice under these conditions is 6.01 Kj/mol.
*March 10, 2011*

**geometry**

I have a isosceles trapezoid question. The top line is 13" long, the sides are 60" long, and the bottom is 27" long. I do not know what is the equation or formula is to determine the acute angle between the bottom and sides or top and sides. Can you please let ...
*March 9, 2011*

**Chemistry**

How many grams of CH3COOH are present in 2.5^3 of vinegar. Also, what is the formula needed to solve? Thanks!
*March 5, 2011*

**Chemistry**

How do I find how many grams of CH3COOH are present in cm^3 of vinegar? Also, how many moles of CH3COOH are present in 2.5 cm^3 of vinegar? Thanks!
*March 5, 2011*

**math**

A computer costs $799. To add memory it costs $25 for 8 megabytes. How much memory can you add if you have at most $1,000 to spend.
*March 1, 2011*

**math**

Last year's computer model is on sale for $799. You can add more memory to the computer. Each chip of 8 megabytes of memory costs $25. How many megabytes of memory can you add if you have at most $1,000 to spend.
*March 1, 2011*

**math**

Last year's computer model is on sale for $799. You can add more memory to the computer. Each chip of 8 megabytes of memory costs $25. How many megabytes of memory can you add if you have at most $1,000 to spend.
*March 1, 2011*

**Math**

Because all of the tickets were square!
*February 24, 2011*

**geometry**

if ac = 2x + 13 and db =4x - 1, what is db
*February 21, 2011*

**Spanish -Please check 7th grade**

Please check my answers-I have to say where I just came from and what I have done using forms of venir and acabar de The post office Vengo del correo. Acabo de mandar una carta. The museum Vengo del museo de arte. Acabo de mirar el arte. The hospital Vengo del hospital. Acabo...
*February 7, 2011*

**Genetics**

Hi, I really need help in how to approach this question: A species of tiny antelope, known as the zephyr, has an XY system of sex determination, similar to mammals. Zephyr males have small antlers and females do not. The antlers can be two pronged (2-pr) or three pronged (3-pr...
*February 6, 2011*

**Math**

A computer costs $799. To add memory it costs $25 for 8 megabytes. How much memory can you add if you have at most $1,000 to spend.
*January 27, 2011*

**chemistry**

The pH of a solution is 6.0. Explain how the addition of the following substance would alter (or not alter) the pH of the solution. a. HCl b. NaOH c. H20
*January 24, 2011*

**Science**

The law of conservation of energy states that energy can neither be created nor destroyed. In many instances it may look as though energy is gained or lost, but it is really only changed in form. How is the law of conservation of energy represented when an archer shoots an ...
*January 5, 2011*

**Physics**

For Part B, do (340+200)/2=270 rpm to find the average rpm during acceleration. Then divide this answer by 60 seconds to find the average revolutions per second during acceleration 270/60=4.5 rev/sec. Multiply this answer by the amount of seconds it takes for it to accelerate ...
*December 11, 2010*

**Physics**

Ball, with a weight of 200 grams, tied to a string rotates around in a horizontal plane. Period of rotation is 2 seconds. What is the force (in N) which acts on the string? The length of the string is 0.5 meters.
*December 8, 2010*

**Math **

how long does it take for a deposit of $1400 to double at 7% compounded continously it would be awesome if you could also tell me how to do it...
*November 9, 2010*

**calculus**

a) -2(x/r) b) Negative c) 2(4.29 / 6400) * 100
*November 9, 2010*

**physics**

Can you figure it out now?
*October 19, 2010*

**physics**

Velocity is a vector quantity, meaning it has both magnitude and direction. Acceleration is the rate of the change of velocity. Therefore, if the speed changes, the object is accelerating (whether it speeds up or slows down). ALSO- if the object is changing direction, the ...
*October 19, 2010*

**Physics**

For this problem, ignore air resistance. You are to fire a rifle that shoots a particular bullet at 460 m/s at a target that is 45.7 m away and level with the rifle. Assuming that the acceleration due to gravity is 9.80 m/s², how high above the target must the barrel of ...
*October 7, 2010*

**physics**

Kinematics Equations: Vx1 = Vx0 + axΔt (Vx1)^2 = (Vx0)^2 + 2axΔx Δx = Vx0Δt + ½ ax(Δt^2) Using the second kinematics equation, we can solve for Δx. (Vx1)^2 = (Vx0)^2 + 2axΔx Plug in what you know: (45 m/s)^2 = (0 m/s) + 2(9.8m/s^2)(? m...
*October 6, 2010*

**science physics**

The speed at which the two objects are approaching each other (from the trains' perspective) is 95 km/h (x 2) = 190 km/h. If they are 7.5 km apart at first, you can set up a proportion: 190 km 7.5 km ------ = --------- 1 hr x hr Cross-multiply the terms and set them equal ...
*October 6, 2010*

**Physics**

For this problem, ignore air resistance. You are to fire a rifle that shoots a particular bullet at 460 m/s at a target that is 45.7 m away and level with the rifle. Assuming that the acceleration due to gravity is 9.80 m/s², how high above the target must the barrel of ...
*October 6, 2010*

**Physics**

I would like to forget the upward component, as the object IS in fact a bullet fired at a fast velocity from a gun towards a target not too far away. However, we're graded on the correctness of our problem solving. And, additionally, this factor WOULD become an issue if we...
*October 6, 2010*

**Physics**

That's not entirely correct... That would only be true if the rifle was fired horizontally, giving the x component 460 m/s towards the target. However, that 460 m/s has some UPWARD y component too, reducing the x component by some amount... Thanks, Steven
*October 6, 2010*

**Physics**

For this problem, ignore air resistance. You are to fire a rifle that shoots a particular bullet at 460 m/s at a target that is 45.7 m away and level with the rifle. Assuming that the acceleration due to gravity is 9.80 m/s², how high above the target must the barrel of ...
*October 6, 2010*

**Physics**

Kinematics Equations: Vx1 = Vx0 + axΔt (Vx1)^2 = (Vx0)^2 + 2axΔx Δx = Vx0Δt + ½ ax(Δt^2) Had the distance from the intersection when braking begins not been given: Remaining distance = 140.0 m Current Velocity = 14.8 m/s Reaction time = 0.440 s ...
*October 6, 2010*

**science**

what is the defination of a compound machine?
*September 20, 2010*

**physics**

A 55 kg student traveling in a car with a constant velocity has a kinetic energy of 1.6 104 J. What is the speedometer reading of the car in km/h?
*September 17, 2010*

**Math**

distance problem suzi drove home at 60mph,but her brother jim,who left at the same time, could drive at only 48mph. When suzie arrived, jim still had 60 miles to go. How far did suzi drive?
*September 14, 2010*

**MATH**

2 tens 5 hundreds
*September 13, 2010*

**chemistry**

Why is the energy for high 2/5 of the energy for the low.
*June 30, 2010*

**Math**

a walk up a hill starts at a car park on the 100m contour and climbs steadily to a summet at 240m. on a map with scale 1:25000 the distance along the path from the car park to the summet is 9.6cm. how long it will to reach su,,it and back according to Naismith's rule.
*June 20, 2010*

**statistics**

A canidatate for governor of a certain state claims to be favored by at least half of the voters. If a hypothesis test is performed, how should you interpret a decision that rejects the null hypothesis? A. There is not sufficient evidence to reject the claim > or = 0.5 B. ...
*June 12, 2010*

**ALGEBRA**

auren and Andrew left Austin at the same time. Lauren traveled east at an average speed of 50 miles per hour. Andrew traveled west at an average speed of 65 miles per hour. How many hours of driving does it take for the two to be at least 500 miles apart? Write an inequality ...
*May 26, 2010*

**Algebra**

An elevator went to the do of a 180m building, stayed for 1 minute, then came down. The total time was 3.5 minutes. If the speed of the elevator when it went up was 1 m/sec less than when it came down, find both speeds (up and down).
*May 20, 2010*

**Algebra**

Thhe members of a soccer team are to share the $540 cost of a banquet. When 5 students are unable to attend the cost per student was $1.50 greater. How many students attended the banquet?
*May 20, 2010*

**algebra**

One paving machine can surface 1 km of highway in 6 hours. Another can surface 1 km of highway in 8 hours. how long would it take to surface 1 km of highway with the two machines working together?
*May 20, 2010*

**physics**

A 100 kg mass starts from rest at the top of an incline plane that makes an angle of 35 degrees with the horizontal. There is a coefficient of friction of 0.005 between the ramp and the mass. The mass slides down the ramp and then slides to a stop on a surface that the ...
*May 14, 2010*

**physics**

A 29 g ice cube at 0.0°C is added to 110 g of water in a 62 g iron cup. The cup and the water have an initial temperature of 25°C. (a) Find the equilibrium temperature of the cup and its contents. i dont understand how the iron cup changes the situation. please help.
*April 26, 2010*

**psychology**

Sexual arousal in human begins is different from that of other animals. It is clear that human sexual arousal can occur:
*April 23, 2010*

**algebra 1**

can u please help me figure out the estimated talk time of 250minutes
*April 22, 2010*

**statistics**

we developed a 95% z confidence interval for the mean BMI of women aged 20 to 29 years, based on a national random sample of 654 such women. we assumed there that the population standard deviation was known to be 7.5. in fact the sample data had mean BMI of 26.8 and standard ...
*April 20, 2010*

**statistics**

at the census bureau web site you can find the percent of adults in each state who have at least a bachelors degree. it makes no sense to find the mean for these data and use it to get a confidence interval for the mean percent U in all 50 states. Why not?
*April 14, 2010*

**statistics**

if young men thought that their own level of muscle was about what women prefer, the mean "muscle gap" in the study would be 0. we suspect that young men think women prefer more muscle than they themselves have. a)what is the value of he test statistic Z? b)you can ...
*April 13, 2010*

**penniman**

what is the estimate quotient for 233 divided by 6?
*March 30, 2010*

**chemistry **

identify the atoms that are being oxidized and reduced.. 2FeCl3 + 2KI --> 2FeCl2 + 2KCl + I2
*March 29, 2010*

**statistics**

in a test for esp a subject is told that cards the experimenter can see but he cannot contain either a star, a circle, a wave, or a square. as the experimenter looks at each of 20 cards in turn, the subject names the shape on the card. a subject who is just guessing has ...
*March 24, 2010*

**statistics**

a binomial distribution will be approximately correct as a model for one of these two sports settings and for the other. explain why by briefly discussing both settings. a)a national football league kicker has made 80% of his field goal attempts in the past. this season he ...
*March 24, 2010*

**statistics**

slot machines are now video games, with outcomes determined by random number generations. in the old days, slot machines were like this: you pull the lever to spin 3 wheels; each wheel has 20 symbols, all equally likely to show when the wheel stops spinning; the three wheels ...
*March 23, 2010*