Wednesday
October 1, 2014

Posts by Ivan


Total # Posts: 102

Material Behavior
The energy-separation curve for two atoms, a distance, r, apart is: U(r)=−A/r^m+B/r^n Derive and expression for the stiffness of the bond at the equilibrium spacing, in terms of A, B, m, n, and r0. S=dF/dr at r=r0:
September 29, 2014

Material Sciences
steel core, what is the thermal stress in the aluminum shell when the system is heated from the unstressed state (20∘C) to 180∘C? Consider only deformations in the axial directions. Give your answer in MPa αAl=23.6×10−6K−1 EAl=70GPa α...
September 27, 2014

Material Sciences
The energy-separation curve for two atoms, a distance, r, apart is: U(r)=−A/r^m+B/r^n Derive and expression for the stiffness of the bond at the equilibrium spacing, in terms of A, B, m, n, and r0. S=dF/dr at r=r0:
September 27, 2014

Physics
The statically-indeterminate composite beam AB of length 2L is fixed at A (x=0) and is simply supported at B (x=2L). The beam is composed of a core of modulus E0 of constant square cross section of dimensions 2h0×2h0 bonded inside a sleeve of modulus 2E0 and constant ...
August 26, 2014

math
A gumball machine contains orange, yellow and purple gumballs. The probability of getting an orange ball is 3/4 and the probability of getting yellow ball is1/6. What is the probability of getting a purple ball?
May 2, 2014

Algebra
List all asymptotes (both horizontal and vertical) of the rational function: f(x)=(10x−3)/(8−7x)
April 7, 2014

Dynamics
A linear spring of stiffness k is designed to stop the 20-Mg railroad car traveling at 8 km/h within 400mm after impact. Find the smallest value of k that will produce the desired result.
March 17, 2014

Physics
A linear spring of stiffness k is designed to stop the 20-Mg railroad car traveling at 8 km/h within 400mm after impact. Find the smallest value of k that will produce the desired result.
March 17, 2014

Dynamics
The man slides the 100-kg crate across force of 200 N. If the crate was initially at rest, how far will the crate move before its speed is 1 m/s? The coefficient of kinetic friction between the crate and the floor is 0.18. The man is pulling the crate at a 20 degree angle.
March 17, 2014

Math
Thank you Ms. Sue I get the same answer. The problem is that teacher offer this answers: a. 29 cm b. 28 cm c. 27 cm d. 33 cm What did we do wrong?
March 8, 2014

Math
The length of a rectangle is 3 cm less than 4 times its width. The perimeter is 74 cm. Find the length
March 8, 2014

Chemistry 2
ok thank you, exactly what i needed to know .
March 3, 2014

Chemistry 2
For the fist order reaction A <-> B, calculate the t1/2(half life) and k(rate constant) and also fill in the blanks. A-Concetration t-time 20 0 10 ? 5 40 sec 3 ? ? 500 sec t1/2=? k=?
March 3, 2014

Chemistry 2
ok thank you, whats the formula to find the time of the missing blanks in the question?
March 3, 2014

Chemistry 2
Thanks man that makes so much clearer. i posted another question similar to this but its a first order reaction. would that change how you work it or is it done the same?
March 3, 2014

Chemistry 2
For a second order reaction A <--> B, calculate the t1/2 (half life) and the k(constant) and also fill in the blanks. A (concentration) t(time) 20 0 sec 10 ? 5 40 sec 3 ? ? 200 sec t1/2=? k=?
March 3, 2014

Chemistry 2
ok i got that now thank you. how will i find the answer for the blanks in the time? is there a formula for it?
March 3, 2014

Chemistry 2
what do you mean?
March 3, 2014

Chemistry 2
For the fist order reaction A <-> B, calculate the t1/2(half life) and k(rate constant) and also fill in the blanks. A-Concetration t-time 20 0 10 ? 5 40 sec 3 ? ? 500 sec t1/2=? k=?
March 3, 2014

Chemistry 2
Thanks man both answers you have answered for me have checked out to mine that i have got.
March 3, 2014

Chemistry 2
When we mix 25.0 mL, 2.0 M BaCl2 with 25.0 mL, 3.0 M Na2SO4 what is the balanced equation? What is the ionic equation? what is the net ionic equation?
March 3, 2014

Chemistry 2
For the reaction: 2A + 3B <--> 4C Kinetic data are as follows A B time needed 10mL 5mL 720 seconds 20mL 5mL 180 seconds 20mL 10mL 90 seconds 30mL 20mL ?? The rate of the equation is?
March 3, 2014

Chemistry 2
Thanks man i appreciate it
March 3, 2014

Chemistry 2
What is the molarity of 50.0 mL solution of aluminum sulfite that contains 80.0 g of this salt? (Al=27.0, S=32.0,O=16.0)
March 3, 2014

Math
If a varies jointly as b and c, and if a = 100 when b = 5 and c = 25, find a when b = 12 and c = 60
February 20, 2014

Math
Thanks Reiny
February 20, 2014

Math
Solve the equation: |6x - 2| = |3x + 1|
February 20, 2014

physics
Participants in a road race take water from a refreshment station and throw their empty cups away farther down the course. If a runner has a forward speed of 6.20 m/s, how far in advance of a garbage pail should he release his water cup if the vertical distance between the lid...
July 7, 2013

Physics
Mary walks west at 2.0m/s for 15 seconds, then north at 3.0m/s for 2o seconds and then east at 4.0m/s for 0 seconds. What is her displacement answer is (108m(N56 DEgrees E)
July 4, 2013

Physics
At that height, you can evaluate the gradient of the normal(which is actually -2.5). then youu find the angle between the horizon and the normal at that height.Let the force acting from the surface along the normal as F.Decompose the force into F_x(parallel to the horizon) and...
June 25, 2013

math
NELSON GOT A PACK OF 12 PENCILS. HE TOOK 3 PENCILS TO PUT IN HIS DESK AT SCHOOL AND 2 PENCILS TO PUT IN HIS LOCKER AT SCHOOL. WHAT IS THE FRACTION OF TOTAL PENCILS THAT NELSON TOOK TO SCHOOL?
January 9, 2013

math
On a sunny afternoon. The stratosphere tower casts a shadow that is 140 meters long. At the same a nearby flagpole that is 10 meters tall cast a shadow that is 4 meters long . Wriré silve the problem
December 12, 2012

Physical Science
A truck whose bed is 2.5m long, 1.5m wide, and 1m high is delivering sand to a construction site. How many trips must the truck make to deliver 7? cubic meters of sand? Plese explain your answer.
November 7, 2012

Physical Science
A truck whose bed is 2.5m long, 1.5m wide, and 1m high is delivering sand to a construction site. How many trips must the truck make to deliver 7? cubic meters of sand? Plese explain your answer.
November 7, 2012

College Physics
This answers is wrong don't use please.
July 6, 2012

physics
A small cork with an excess charge of +7.0 µC is placed 0.16 m from another cork, which carries a charge of −3.2 µC. What is the magnitude of the electric force between the corks? The Coulomb constant is 8.98755 × 10 9 N · m2 /C 2 . Answer in ...
February 26, 2012

physics
Calculate the net charge on a substance consisting of a combination of 8.9 × 10 13 protons and 4.4 × 10 13 electrons. Answer in units of C
February 26, 2012

physics
A negatively charged balloon has 4.5 µC of charge. How many excess electrons are on this balloon? Answer in units of electrons
February 26, 2012

physics
An unclothed student is in 24 ◦ C room. If the skin temperature of the student is 37 ◦ C, how much heat is lost from his body in 6 min, assuming that the emissivity of the skin is 0.83 and the surface area of the student is 1.5 m2 . The Stephan-Boltzmann constant ...
February 19, 2012

Physics
During a certain thermodynamic process a sample of gas expands and cools, reducing its internal energy by 3690 J, while no heat is added or taken away. How much work is done during this process?
February 19, 2012

English
I need help on; how to contrast Walt Whitman perspective of America with the perspective that the members of Occupy Wall Street and the the Tea Party movement have about America.?
January 7, 2012

Pre-calculus
2^(x)/(1-2^(x))=3
December 12, 2011

physical science
absolute zero is the same as
November 27, 2011

chemistry
hey! help me
November 6, 2011

chemistry
in saturated sugar solutions what is the solute? what is the solvent?
November 6, 2011

phy
A 3.50 kg block on a smooth tabletop is attached by a string to a hanging block of mass 2.80 kg. The blocks are released from rest and allowed to move freely. 1-Is the tension in the string greater than, less than, or equal to the weight of the hanging mass? 2-Find the ...
July 18, 2011

phy
correction i- 92 mi/h ii- 0/15 m iii- 803 N
July 16, 2011

phy
A major-league catcher gloves a 92 {\rm mi}/{\rm h} pitch and brings it to rest in 0.15 {\rm m}. 1-If the force exerted by the catcher is 803 {\rm N}, what is the mass of the ball?
July 16, 2011

chemistry
1-why should the maximum percent yield never be above 100%?
July 16, 2011

history
2. Why did European economic practices and financial institutions (trading companies, banks, investments, creation of global markets) weaken Middle Eastern and Asian economies and upset local politics? 3. How did countries or empires in the Middle East and Asia attempt to ...
June 8, 2011

history
How did European explorations and commercial activities in the early modern period affect regions of the Middle East and Asia?
June 8, 2011

math
10 degrees of circle in fraction
May 10, 2011

nalya sec sch
do people accomplish more to do things in thiere own way
April 25, 2011

Geometry
How large is an angle whose supplement is three times its complement?
January 18, 2011

Geometry
If we want to find the height of an object like a flagpole, what type of triangle do I use?
January 18, 2011

Geometry
An alloy of copper is 10% copper and weighs 25 pounds. A second alloy is 18% copper. How much (to the nearest tenth lb.) of the second alloy must be added to the first alloy to get a 13% mixture.
January 18, 2011

Geometry
Find the area of the bedroom in square feet of 11' x 13' 10"
January 18, 2011

Geometry
If a rectangular lot measures 120 ft. x 80 ft., and 10 foot set backs are required from each lot line, how much area is left? If a kennel for 50 dogs requires 12,500 square feet, how many dogs can be accommodated in the small rectangle?
January 18, 2011

Geometry
Mr. Thompson has been asked to add storage space to a garage. He estimates 6 square feet per individual will be required to meet the needs of 12 people. If the storage space is 15% of the total amount of space required, how much total space does Mr. Thompson have?
January 18, 2011

Geometry
Two angles are complementary. One contains 20° more than the other. Find both angles.
January 18, 2011

Geometry
If the boy is 4' 9" tall and his shadow is 6 ft. and the shadow of the flagpole is 19 ft., determine the height of the flagpole (to the nearest tenth).
January 17, 2011

Geometry
The sides of a triangular lot are represented by x, 2x, and 3x + 2. Find each side if the perimeter is 362 feet. What are the 3 lengths?
January 16, 2011

Geometry
A square measures 8 inches on each side. What is its area rounded off to the nearest whole number. (Note: 1 inch ≈ 2.54 cm)
January 16, 2011

Geometry
A trapezoid has an altitude of 12 cm. Its parallel sides measure 10 and 8 cm, respectively. What is it's area?
January 16, 2011

Geometry
Compute the area of the triangle. (Express answer in cm2) h = 6 cm b = 12 cm a = How many cm2?
January 16, 2011

Geometry
Compute the area of a triangle with sides. 15 × 15 × 18 a = How many square units?
January 16, 2011

Geometry
A lot is in the shape of a trapezoid. The sum of the bases is 180 feet. If the area of the lot is 8,100 square feet, what is the distance across the lot, i.e., the altitude of the figure? The altitude of the trapezoid is how many feet?
January 16, 2011

Geometry
a = 12 ft. b = 8 ft. a = How many sq. ft. ?
January 16, 2011

Geometry
a = 12 cm b = 14 cm h = 8 cm. Compute the area. How many cm2?
January 16, 2011

Geometry
Find the area of the following circle. r = 9 yd. a = How many square yards?
January 16, 2011

Geometry
Find the area of the following ellipse (round to nearest tenth). a = 9 in.; b = 8 in. a = How many sq. in.?
January 16, 2011

Geometry
Find the area of the following ellipse (round to nearest tenth). 2a = 10 cm; 2b = 24 cm. a = How many cm2?
January 16, 2011

Geometry
A contractor is pouring a concrete driveway. The perimeter is 108 ft. What length will the driveway be if the width is 12 ft.? How many feet is the Drive Way?
January 16, 2011

Geometry
A gardener is installing a circular garden. The radius of the circle 28 feet. He needs to know the circumference in order to buy materials for the edging. What is the circumference if he uses = 22/7. The circumference is ?
January 16, 2011

Geometry
Find the area of the following circle. ( = 3.14; round answer to the nearest whole number). Circumference = 120 cm. (Hint: Find r from C = 2r (round r to tenths); then find area).
January 16, 2011

calculus5
I understand what you guys think I am a soldier on duty and I have to turn these in I am runnning out of time and I need help thanks
November 28, 2010

calculus5
(y^2+2)^3=x^4y+e^2 find dy/dx using differentiating implicity
November 28, 2010

calculus4
2y^3-y=7-x^4 find dy/dx using differentiating implicity
November 28, 2010

calculus3
x^2/3+y^2/3=5 find dy/dx using differentiating implicity
November 28, 2010

calculus2
x^2+2y^2-11=0 find dy/dx using differentiating implicity
November 28, 2010

calculus1
x^5-5y=6-x find dy/dx using differentiating implicity
November 28, 2010

Calculus
6x-3y=4 find dy/dx using differentiating implicity
November 28, 2010

Physics
Four identical 12µC charges are placed at the corners of a square of sides 44 cm, with one additional 12µC charge placed at the center. Find the electric potential at the midpoint of one of the sides.
November 12, 2010

Calculus 1
Calculate f'(-1) f(x) = x^7 * h(x) h(-1) = 5 h'(-1) = 8 Answer is 27, but I got no idea how to get there.
October 28, 2010

french
"How many days are there in the month of october?"
October 28, 2010

3rd math homework
6-4=2 2+4=6 you can use other numbers too 6-5=1 1+5=6 etc.
October 28, 2010

Math.
420cal = 2.25 cans ? cal = 1can To find the number of calories we just do the cross product, so: 420cal x 1can / 2.25cans = ? cal 420cal/2.25cans = 186.6667cal
October 28, 2010

English check
Lasted only about a century as a way of life but has persisted as an influence
August 24, 2010

Electronic Timing inc
good
March 30, 2010

sunshine math-4
mark hid a 10 bill inside his favorite book. he forgot the pages where he hid it. is the sum of the pages where the bill is hidden is 177, on what pages will mark find his money
March 16, 2010

math
use the digets 2,4,6,and 8 to create an expression with a value of 2
October 6, 2009

Alegebra 1
1/35
September 8, 2009

Stoichiometry
6 NaOH + 2 Al ---> 2 Na3AlO3 + 3 H2 How many moles of NaOH are required to produce 3 g of hydrogen?
March 22, 2009

Calculus
find the x-coordinate of the point P on the parabola y=1-x^2 for 0<x<1 where the triangle that is enclosed by the tangent line at P and the coordinate axes has the smallest area.
November 6, 2008

writing
Is this a run-on: Martha moans and groans upon getting in the morning she sounds like a crazy woman.
June 25, 2008

science
eukaryote
May 27, 2008

eukaryoyoinacrosticpoem
into
May 27, 2008

READING
HELP ON HOW TO START A 5TH GRADE BOOK REPORT
March 16, 2008

math
4 HR AND 47 MIN, WHAT I DONT UNDERSTAND IS WHY DO I CHANGE 6:30 to 5:90, thank you Ms.Sue
February 4, 2008

math
FIND THE ELAPSED TIME START 1:43 FINISH 6:20 HOW DO I FIND IT
February 4, 2008

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