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August 30, 2014

Posts by bob


Total # Posts: 2,372

chemistry
Surface tension explains which of the follow- ing phenomena? I) A piece of aluminum foil floating on a lake II) A bowling ball sinking more slowly through molasses than through water III) Separating ethanol from water by distillation IV) Water beading on a windshield during ...
November 14, 2010

Physics
you use the mg-(2.3E2*cos21)for fnormal...bobpursley you really should check your work before...
November 13, 2010

economics
drop in output
November 11, 2010

geomtry
Figure it out
November 11, 2010

physics
How much spring elasticity would be needed to make a 50 pound child jump higher
November 10, 2010

Physics
17.4
November 10, 2010

physics
A bus traveling 85 km/hr is brought to a stop in 135 m. If the mass of the bus is 2250 kg, what was the retarding force provided by the brakes? Formula please
November 9, 2010

Algebra
Thank you
November 8, 2010

Algebra
why 32?
November 8, 2010

Algebra
4a/16 + a/16 =?
November 8, 2010

1st grade
the girls past was bad
November 8, 2010

physics
A man pushes on a piano of mass 180 so that it slides at a constant velocity of 12.0 down a ramp that is inclined at 11.0 above the horizontal. No appreciable friction is acting on the piano. Calculate the magnitude and direction of this push A. if the man pushes parallel to ...
November 8, 2010

chemistry
A propane barbeque is used to heat up 400g of water in an aluminum pot until it is boiling. Using the following information, calculate the molar enthalpy of propane. You can assume the temperature of the water and the temperature of the aluminum pot are always the same. ...
November 7, 2010

chemistry
A 10.0 g sample of liquid gallium metal, at its melting point, is added to 50.0g of water. The initital temperature of the water is 24.0 degrees C. If the molar enthalpy of freezing gallium is -5.54 kj/mol, what is the final temperature of the water? Thanks
November 7, 2010

PHILOSOPHY
What was William of Ockham's position on predestination? Where is a good sight to find imformation on this subject?
November 7, 2010

math
What are the measures of the angles of a right triangle with side lengths of 1, 2, and sqroot of 2? please show/explain work
November 7, 2010

MATH
a ball of radius 1 is dropped into a V-shaped gutter. The ball touches the gutter's sides at the ball's equator. If the shortest distance from the surface of the ball to the vertex of teh gutter is 1, what is the angle formed by the sides of the gutter?
November 7, 2010

math
a ball of radius 1 is dropped into a V-shaped gutter. The ball touches the gutter's sides at the ball's equator. If the shortest distance from the surface of the ball to the vertex of teh gutter is 1, what is the angle formed by the sides of the gutter?
November 7, 2010

math algebra
how would i do this problem elina and teresa raced on their bikes to the library after school. they both left at 3:00 pm and bicycled along the same trail elina rode at the speed of 12 miles an hour and teresa rode at the speed of 9 mph. elina got there 15minutes before teresa...
November 4, 2010

calculus
A rectangle is constructed with its base on the diameter of a semicircle with radius 5 cm and with two vertices on the semicircle. What are the dimensions of the rectangle with maximum area?
November 4, 2010

calculus
A square-based, box-shaped shipping crate is designed to have a volume of 16ft^3. The material used to make the base costs twice as much (per ft^2) as the material in the sides, and the material used to make the top costs half as much (per ft^2) as the material in the sides. ...
November 4, 2010

chem
A scuba diver's tank contains .25 kg of oxygen compressed into a volume of 4.3 L (for oxygen, 32g = 1 mole) Calculate the gas pressure inside the tank at 9 degrees Celsius What volume would this occupy at 26 degrees Celsius and .95 atmospheres? can someone tell me how many...
November 2, 2010

chemisty help please
I still don't get it.. lol
November 2, 2010

chemistry
I looked at that guys and i still dont get it.
November 2, 2010

chemistry
A scuba diver's tank contains .25 kg of oxygen compressed into a volume of 4.3 L (for oxygen, 32g = 1 mole) Calculate the gas pressure inside the tank at 9 degrees Celsius What volume would this occupy at 26 degrees Celsius and .95 atmospheres?
November 2, 2010

Algebra
Hot Java Coffee Company adverties their decaffeinated coffee as 97% caffeine free as compared to their regular caffeinated coffee. If a cup of coffee is 8 ounces, how many ounces of decaffeinated coffee would you have to drink to get the equivalent amount of caffeine found in ...
November 2, 2010

chemistry
What volume of HCl gas is produced by the reaction of 2.4 liters of H2 gas with 1.5 liters of Cl2 gas? (Volumes are at the same T and P.) 1. 3.0 liters 2. 4.8 liters 3. 0.75 liters 4. 2.4 liters 5. 1.5 liters
November 1, 2010

Word within the Word Analogy Help
how fast can you answer??
November 1, 2010

chemistry
Thanks, I thought I could use Boyle's Law, but it seemed too easy.
November 1, 2010

chemistry
Two gases are contained in gas bulbs connected by a valve. Gas A is present in a 56 L bulb at a pressure of 213 torr. Gas B exerts a pressure of 683 torr in a 74 L bulb. What is the partial pressure of gas B after they equilibrate once the valve has been opened? Answer in ...
November 1, 2010

chemistry
Calculate the number of carbon atoms in 0.75 L of acetone (CH3COCH3). (density = 1.3 g/mL and boiling point = 48.5 degrees Celsius)
October 31, 2010

chemistry
CaCN2
October 31, 2010

chemistry
Consider the following reaction: CaCN2 + 3H2O ¨ CaCO3 + 2NH3 105.0 g CaCN2 and 78.0 g H2O are reacted. Assuming 100% efficiency, which reactant is in excess and how much is leftover? The molar mass of CaCN2 is 80.11 g/mol. The molar mass of CaCO3 is 100.09 g/mol. 1. ...
October 31, 2010

poetry
Can someone explain what the poem is trying to tell in "Ode to the West Wind" I read from other sites but I don't understand it... I believe that it is talking about death...
October 29, 2010

biochemistry
wfwfrgffdgbhyujhyujb
October 29, 2010

chemistry
89.8%
October 27, 2010

physics
find the force exerted by the rope on the car when the angle is 2.9 degrees and you are pulling with a force of 384 N but the car does not move
October 27, 2010

calculus
Find parametric equations for the line through the point P(2, 9, 4) that is parallel to the plane x + y + z = 6 and perpendicular to the line x = 5 + t , y = 5 − t , z = 5t . Answer Choices: 1. x = 2 + 6t, y = 9 + 4t, z = 4 + t 2. x = 2 + t, y = a + t, z = 4 − 2t ...
October 27, 2010

calculus
Find an equation for the surface consisting of all points P(x, y, z) equidistant from the point P(0, 1, 0) and the plane x = 3. Answer Choices: 1. y2 + z2 − 6x + 2y − 8 = 0 2. x2 + z2 + 6y − 2z − 8 = 0 3. y2 + z2 + 6x − 2y − 8 = 0 4. x2 + z2...
October 27, 2010

calculus
If a is a vector parallel to the xy-plane and b is a vector parallel to k, determine |a ~ b| when |a| = 3 and |b| = 2. 1. |a ~ b| = −6 2. |a ~ b| = −3ã2 3. |a ~ b| = 3 4. |a ~ b| = 3ã2 5. |a ~ b| = 0 6...
October 27, 2010

Statistics
z = 50
October 26, 2010

physics
fail...
October 25, 2010

physics
You are given a vector in the xy plane that has a magnitude of 84.0 units and a y component of -49.0 units. Assuming the x component is known to be positive, specify the vector V which, if you add it to the original one, would give a resultant vector that is 71.0 units long ...
October 25, 2010

physics
NVM!
October 25, 2010

physics
When Mary is 22 m from the finish line, she has a speed of 4.0 m/s and is 5.0 m behind Sally, who has a speed of 5.0 m/s. Sally thinks she has an easy win and so, during the remaining portion of the race, decelerates at a constant rate of 0.51 m/s^2 to the finish line. What ...
October 25, 2010

american studies
henry hudson
October 24, 2010

Physics
If a car starts from rest and travels for 5.0 seconds with a uniform acceleration of +1.5 m/s2. The driver then applies the brakes for 3.0 seconds, causing a uniform acceleration of - 2.1 m/s2.
October 23, 2010

physics
isnt it 9.81 m/s^2?
October 22, 2010

math
wolfram alpha!
October 21, 2010

physics
it was a stupid format and i ran out of tries. Basically it wanted me to divide .707 by .293. The worst part is that it was worth a lot =[ o well
October 21, 2010

physics
In the vertical jump, an Kobe Bryant starts from a crouch and jumps upward to reach as high as possible. Even the best athletes spend little more than 1.00 s in the air (their "hang time"). Treat Kobe as a particle and let ymax be his maximum height above the floor. ...
October 21, 2010

physics
so i get v(t)=-(13*5)/t
October 21, 2010

physics
I would know how to solve this problem if i were to understand the whole t/t_0 thing. I dont know how to integrate something like that. Could you please explain how to get it started
October 21, 2010

physics
The velocity of a particle constrained to move along the x-axis as a function of time t is given by: v(t)=-(13/t_0) sin(t/t_0). a)If the particle is at x=4 m when t = 0, what is its position at t = 5t_0. You will not need the value of t_0 to solve any part of this problem. b)...
October 21, 2010

physics
What angle does the tangent to the curve y(x)=sin^2(x/9)+16sin(x/9) at x=9\pi make with the x-axis?
October 21, 2010

physics
E^2/(e^(E/T)-1)Evaluate dn/dE at fixed T and enter it below.
October 21, 2010

College Chemisty
Al
October 20, 2010

Math [Interest]
Okay, so I've been away from school for three weeks, and we have a math test tomorrow. I only just found out, and my friend emailed me the review questions. If someone could help me out, and show me how to do this, I'd appreciate it. No, I do not want someone to do my ...
October 20, 2010

math
it is impossible
October 20, 2010

Finance
21
October 20, 2010

spanish
what does que te encatanda mas,el chocolate o la pizza mean
October 19, 2010

Physical Science
Would the change be a negative number?
October 19, 2010

Physical Science
A 1.0 kg glass bowl at 37 °C is placed in a freezer. How much heat will the freezer have to remove from the bowl to take it to 0 °C? (cglass = 0.2 cal/deg-gm)
October 19, 2010

Trig
If b=5 , the angle C=50 and the angle A=50 find the other angle B and the remaining sides and . Give your answer to at least 3 decimal places.
October 18, 2010

engineering
Using mechanics of materials principles, (i.e. equations of mechanical equilibrium applied to a free-body diagram), derive the following equations: s’ = s cos2q = s[(1+ cos 2q) / 2] t' = s sinq cosq = s [sin 2q / 2] s=sigma, q=theta, t=tau I have looked in "...
October 18, 2010

Math Algebra
kassie an kesya are dividing $39 into two parts in order that the sum of 2/3 of one part and 3/4 of the other part is $28. What are the parts?
October 18, 2010

PLEASE HELP
WOULD IT BE 13 OVER 30
October 17, 2010

PLEASE HELP
PLEASE ANSWER THE FRACTION 14 OVER 15 - THE FRACTION 1 OVER 2. HURRY!
October 17, 2010

calc
(e^x + e^-x)/2=1
October 17, 2010

Math
so the answer is 7/12?
October 17, 2010

history
i know how to write an essay, it's this topic that i need help with, like what can you learn from it? and was it neccesary or not?
October 17, 2010

history
explain reign of terror face in the french revoloution. discuss robesperre's involvement and evolution of \his political views. do u think it was neccessary in the revolution? what lessons can be learned from this event? i have to write an essay on this please give me any ...
October 17, 2010

math
wouldnt the distance be 3 miles though if the one mile train must travel 1 mile (distance of itsself) plus the distance of the other train which is 2 miles?
October 17, 2010

math
a freight train that is 1 mile long is traveling at 60mph. a second train that is 2 miles long is traveling 40mph. the trains are moving in opposite directions on parallel tracks. how many seconds does it take between the time their locomotives meet and their cabooses fully ...
October 17, 2010

math
find a such that f(x)= ax2-4x+3 has a maximum value of 12
October 16, 2010

math
find a such that f(x)= ax2-4x+3 has a maximum value of 12
October 16, 2010

calculus
Find the area of the region lying inside the polar curve r = 2(1 − cos theta) and outside the polar curve r + 4 cos(theta)= 0.
October 13, 2010

calculus
Find the area of the region lying inside the polar curve r = 2(1 − cos theta) and outside the polar curve r + 4 cos(theta)= 0.
October 13, 2010

calculus
find the area of the region bounded by the polar curve r=sqrt(6ln(theta)+3 as well as the rays theta=1 and theta=e
October 13, 2010

Algebra 2
Let (x1,y1) be a solution, other than (0,0), of a direct variation equation. Write an second direct variation equation whosegraph is perpindicular to the graph of the first equation.
October 12, 2010

Physics
Two identical point charges are fixed to diagonally opposite corners of a square that is .5m on a side. Each charge is 3.0E-6 C. How much work is done by the electric force as one of the charges moves to an empty corner?
October 11, 2010

Science
A mixture of 10.902 g if iron(II) oxide and 6.524 g of aluminum metal is placed in a crucible and heated in a high temperature oven, where a reduction of the oxide takes place: 3 FeO(s) + 2Al(ℓ) ! 3 Fe(ℓ) + Al2O3(s) . What is the limiting reactant? What is the ...
October 10, 2010

Chemistry
1.19 atm
October 8, 2010

chemistry
express liquid pentanol and gaseous oxygen as a chemical reaction
October 8, 2010

math
andy has 23 coins worth 3.65 consisting of only quarters and dimes.how manydimes does he have?
October 5, 2010

VESPR theory
But is a molecule with an electronic geometry of tetraheydral and a molecular geometry of bent the only one like that? Why doesn't a square pyramidal have <120 degree angles when it has a lone pair? Or does it? I feel like more of the bond angles should be less than the...
October 5, 2010

VESPR theory
On one of my pages of notes, it lists all the different shapes and the bond angles that go along with them. Next to bent (2 lone pairs, 2 bonds), it says <109.5 degrees for bond angles. I don't understand why that one is less than 109.5, when a trigonal pyramidal isn&#...
October 5, 2010

VESPR theory
Is a bent tetraheydral the only shape that doesn't have a precise angle (as in it's less than 109.5 degrees)?
October 5, 2010

Physics
Forgot to put my question at the end of it XD This is from me trying to interpret what you've done in the previous times this question has been asked, but obviously, I'm wrong somewhere. At what point in the work am I messing up?
October 3, 2010

Physics
Let me try to clarify v1=22.222 m/s v2=13.278 m/s x=vi(t)+1/2a(t^2) 56.7=22.222t+1/2a(t^2) 24.4=13.278t+1/2a(t^2). Through elimination 32.3=8.94t t=3.611s From there I separated to -vi=at as vf is 0 -22.222=a(3.611) -13.278=a(3.611) -35.5=7.222a a=-4.92 m/s^2
October 3, 2010

Physics
To stop a car, you require first a certain reaction time to begin braking. Then the car slows under the constant braking deceleration. Suppose that the total distance moved by your car during these two phases is 56.7 m when its initial speed is 80.0 km/h, and 24.4 m when the ...
October 3, 2010

calculus
Find the sum of the series (-1)^n (5^(2n))/n! 1. sum = e^25 2. sum = e^−5 3. sum = 5 4. sum = e^5 5. sum = 25 6. sum = e^−25
September 30, 2010

calculus
017 10.0 points Lance Armstrong is moving with speed 35 feet/sec and acceleration 4 feet/sec2 when he crosses the starting line of a stage in the Tour de France. Use a degree two Taylor polynomial T2(t) to estimate how far he travels in the next second. 1. distance = 38 feet 2...
September 30, 2010

1st grade
2 bones + 3 dogs is 5 objects or 2 bones - 3 dogs = -1 bones
September 27, 2010

Chemistry
What is the chemical equation for white flour? Thanks!
September 27, 2010

Chemistry
How many molecules are in 2.6 grams of H2O?
September 26, 2010

phy
a=6750
September 26, 2010

calculus
With power series, is an endpoint convergent if you plug it back into the original series, and get an alternating series that is conditionally convergent?
September 22, 2010

Chemistry 1145
These UV photons can break chemical bonds in your skin to cause sunburn—a form of radiation damage. If the 310 nm radiation provides exactly the energy to break an average chemical bond in the skin, estimate the average energy of these bonds in \rm kJ/mol.
September 22, 2010

Algebra 1
trtyrt
September 21, 2010

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