Thursday
July 31, 2014

Posts by Luc


Total # Posts: 67

readings
In his 1992 speech, how did Mikhail Gorbachev view the impact of the global communications revolution on the people of less-developed countries?

readings
Rather than promoting goods and manufactures, the 1939 New York World's Fair sought to emphasize

physics
1 junction of a thermocouple is kept in melting ice and the other in boilin H20.The readin of currnt on a micro ammeter is 96mA.The micro ammetr reads 60mA when the hot junction is immersed in hot H2O.Find the temperature of the hot H20

physics
A Hg thermomtr is calibrated by immersing it in melting ice and thn in boiling H20.The column of the Hg is respctively 2.9cm &29cm.Find the temperature whn the column is 10cm long

physics
The density of helium is 0.179kgm3.A Baloon hs a capacity of 27m3 and a mas of 12.5kg whn empty.a)fnd the total mas of baloon n gas.b)if dnsity of air is 1.29 kgm3 wht mas of air is displacd by the baloon

physics
What is the volume of a metal which weighs 28g less in kerosene and the densty is 800 kgm3 than it does in air

Chemistry
I'm abit confusd hw to find the% of H2O of crystallization Na2SO4.10H20

chemistry
Can u help me plz.A compound producd 1200cm3 of N2 @ rtp.a) how many N2 molecules were in the sample & wat mas of N2 is producd

chemistry
Ben has 1L of 0.1mol/dm3 solution of KI & wish to take a sample containing 8.3g of solute.What volume should he measure

chemistry
An element x has 3 isotopes,a,b,c.a has 5% abundance b,20%,c,75% &a has a mas of 40,b 42,c 45.what is the essntial differnce in the nuclear structure.

physics
A density bottle has a mass of 35g when empty,85g when filled with water and 75g when filled with kerosene.Calculate the density of kerosene in g/cm3

chemistry
You are provided with supply of 2M SO4.Explain how you may prepare 500ml of 0.5M SO4.

chemistry
50ml of 0.3M SO4 is titrated against KOH & end point is reached when 35.3 ml of the acid is added.find the molarity of the alkali

chemistry
A sample of a compound is found to contain 21.84kg of phosphorous &28.16g of O2.find its emphirical formula

chemistry
Calculate the mass of carbon dioxide produced by burning 0.60kg of methane

chemistry
Calculate the % by mass of carbon in octane

chemistry
In the reaction:Zn+ 2HCL>ZnCl2+h2.What mass ZnCl2 is produced when 10g of zn reacted

chemistry
In the reaction:Zn+ 2HCL>ZnCl2+h2.What mass ZnCl2 is produced when 10g of zn reacted

chemistry
An element with relative atomic mass 20.8 is found to contain 2 isotopes having a relative atomic mass of 20 and 21.Find the % composition of the element.

math
What is the dormain and range of h(x)=|2x -3|-1

math
What is the dormain and range of g (x) =square root of x-5

math
What is the dormain and range of square root of x-5

science
Given that P(x)=x(x^2-13) +12,express P(x)as a product of linear factors.

physics
Given that x-2 is a factor of x^3-4x^2-2x +k,find k.

physics
A student lifts a box that weighs 185N.The box is lifted0.8m.the stdnt drps the bx.hw much gravity do on the bow whn it falls0.8m.

physics
A rope is usd to pull a box 15mt across the floor.the rpe is @an angle of 46dgree to the horizntal. A force of628N is dne by the rope to the box.hw much work does the rope do on the box

physics
A man pushs a cart wt a force of 36N directd@ an angle 25dgree belw the horizontal. The horizntal comp oe the force is 32.6N.The vrticl comp of force is 15.6N.Fnd work dne on the cart as the prsn moves50m

physics
A persn carries a 218N suitcse up a stairs.the displcment is 4.20m vertically & 4.60m horizntally. A.hw much work does the person do on the suitcase B. If the prsn carries the same suitcse dwn.hw much work does he do

physics
A car of mass 1200kg travelling @ 72 km/h is brought to rest in 4s and has a deceleration of 5m/s find the distance moved during the deceleration

physics
A load of 500N is raised 0.2m by a machine in which an effort of 150N moves 1m.What is a) the work done on the load b)the work done by the effort c)the efficiency

physics
A)When the energy input to gas fired power station is 1000MJ,the electrical energy output is 300MJ.What is the efficiency of the power station in changing the energy in gas into electrical energy b)what form does the 700MJ of lost energy take c)what is the fate of the lost energy

physics
In loading a lorry a man lifts boxes each of weight 100N throughta height of 1.5 m. a)how much work does he do in lifting 1 box b)how much energy is transferred when 1 box is lifted c)if he lifts 4 boxes/minute@ what power is he working

physics
A car of mass 1200kg travelling @ 72 km/h is brought to rest in 4s.Find a) the average deceleration b)the average braking force

physics
A hiker climbs a hill 300m high.If she weighs 50kg,calculate the work she does in lifting her body to the top of the hill

physics
How much work is done when a mass of 30N is lifted vertically through 6m

physics
A block of mass 2kg is pushed along a table with a constant velocity by a force of 5N.When the push is increased to 9N,what is a)the resultant force b)the acceleration

Physics
A chair lift carries people of average mass 75kg to a height of 450m above the starting point. Calculate a) the work done by the chair lift to move one person through 450m. b) the power expended to carry 60 people every 5 minutes.

physics
A box of mass 5 kg is pulled along a horizontal frictionless surface by a force of 40N inclined @ 30dgrees. Calculate A)the work done by the force over a distance. B)the speed gained by the box after travelling 10m.

science
An 80kg golf hall is struck for a period of0.03s wt a force of 500n.the bal accelerate frm the tree.wat is its final speed.

physics
An archa fires an arrw of mas 96g wt a velocity of 120m/s @a target of mas 1500g hangin frm a piec o strin frm a tal tree. If the arrow becomes embedded in thd target wt wat velocity does the target move

Algebra 1
what about part 2 ?

Chemistry
Calculate the average translational kinetic energy (kJ/molecule) for a molecule of NH3 at 431 K, assuming it is behaving as an ideal gas. I understand how to figure out the kJ/mole, but I don't understand how to get the kJ/molecule that this question is asking for. Can som...

Chemistry
I tried the method that you provided above and the grading system told me that the answer was wrong. The correct answer is (0.3775). Do you know how to come up with that answer?

Chemistry
If 0.433 mol of gaseous CS2 and 1.62 mol of gaseous H2 are reacted according to the balanced equation at 454 K and in a 40.0 L vessel, what partial pressure (atm) of gaseous CH4 is produced? CS2(g) + 4H2(g) -> CH4(g) + 2H2S(g) Molar Mass (g/mol) CS2 76.143 H2 2.016 CH4 16.043

Chemistry
I get the same answer as before = 0.271atm According to the program, the right answer is 0.391atm

Chemistry
Yes it is based on mole composition, not mass. But how do you figure out the moles?

Chemistry
A gas sample containing only SO2, PF3 and SF6 has the following mass percent composition: 30.4% SO2 and 28.4% PF3. Calculate the partial pressure (atm) of SO2 if the total pressure of the sample is 676.4 torr. I tried taking the total pressure in atm and multiplying it with th...

Chemistry
I came up with 3461 torr, but the homework program I am using said that the correct answer is 2510 torr. So, I either did something wrong, or the method provided above does not work

Chemistry
A gas sample containing only SO3, CH2O and C2H6O2 has the following mass percent composition: 65.1% SO3 and 8.79% CH2O. Calculate the partial pressure (torr) of SO3 if the total pressure of the sample is 4712 torr. Unit conversion K = C + 273 1 atm = 760 torr Molar Mass (g/mol...

Chemistry
A 355.0 mL cylinder containing SO3 at a pressure of 0.700 atm is connected by a valve to 0.559 L cylinder containing COCl2 at 380.0 torr pressure. Calculate the partial pressure (atm) of SO3 when the valve is opened. Unit conversion K = C + 273 1 atm = 760 torr Molar Mass (g/m...

Chemistry
never mind, I figured it out. I'll post the explanation just in case anyone else needs help with a similar problem. Equation: molality acetone = mol acetone/kg ethanol ------------------------------------- to find kg ethanol: total mass - sample mass of acetone (6.56kg - 1...

Chemistry
Calculate the molality (m) of a 6.56 kg sample of a solution of the solute acetone dissolved in the solvent ethanol if the sample contains 1.44 kg of acetone. Additional info: Molar Mass (g/mol) acetone = 58.05 ethanol = 46.07 Density (g/mL) acetone = 0.7899 ethanol = 0.7893 D...

Chemistry
Thank you Dr. Bob!

Chemistry
A 1.33 m solution of the solute diethyl ether dissolved in the solvent tetrahydrofuran is available. Calculate the mass(kg) of the solution that must be taken to obtain 0.4716 kg of diethyl ether. Name/Formula: diethyl ether = (C2H5)2O tetrahydrofuran = C4H8O Molar Mass(g/mol)...

Chemistry
-637 kJ/mol. okay, I understand now... thanks Dr. Bob!

Chemistry
∆H⁰rxn, for the reaction of Ca(s) + 2H+(aq) -> Ca2+(aq) + H2(g) is -544 kJ/mol. ∆H⁰rxn, for the reaction of CaO(s) + 2H+(aq) -> Ca2+(aq) + H2O(l) is -193 kJ/mol. Based on these results, what is the ∆Hf for CaO(s) [in kJ/mol] if the heat of f...

chemistry
An element has hcp packing with a hexagonal unit cell. Its density is 21000 kg/m3 and the unit cell volume is 2.94 x 10-23 mL. Calculate the molar mass (g/mol) of the element to three significant figures.

Chemistry
An element has ccp packing with a face-centered cubic unit cell. Its density is 12400 kg/m3 and the unit cell volume is 5.50 x 10-29 m3. Calculate the molar mass (g/mol) of the element to three significant figures. Please explain how you come to the answer.

Chemistry
The element palladium has ccp packing with a face-centered cubic unit cell. The density of Pd is 12 g/cm3. Calculate the volume (L) of the unit cell of Pd.

physics newtons laws 3
The coefficient of static friction between the m = 3.20 kg crate and the 35.0° incline of Figure P4.41 is 0.260. What minimum force must be applied to the crate perpendicular to the incline to prevent the crate from sliding down the incline?

physics newtons laws
A box of books weighing 280 N is shoved across the floor of an apartment by a force of 390 N exerted downward at an angle of 35.1° below the horizontal. If the coefficient of kinetic friction between box and floor is 0.57, how long does it take to move the box 4.00 m, star...

physics newtons laws
A 184 N bird feeder is supported by three cables. angle 1 is 60 degrees and angle 2 is 30 degrees Find the tension in each cable.

physics newtons laws
A 184 N bird feeder is supported by three cables. angle 1 is 60 degrees and angle 2 is 30 degrees Find the tension in each cable.

physics
A box of books weighing 280 N is shoved across the floor of an apartment by a force of 390 N exerted downward at an angle of 35.1° below the horizontal. If the coefficient of kinetic friction between box and floor is 0.57, how long does it take to move the box 4.00 m, star...

physics
A 40.0 kg wagon is towed up a hill inclined at 17.9° with respect to the horizontal. The tow rope is parallel to the incline and has a tension of 140 N. Assume that the wagon starts from rest at the bottom of the hill, and neglect friction. How fast is the wagon going afte...

physic
A turnbuckle is needed to apply an 8kN force on a cable. If the efficiency of the turnbuckle is 40% and the force applied is 159.155N with a lever of 20cm in length. a) Find the mechanical advantage. b) Find the velocity ratio. c) Find the mean pitch of thread.

Accounting
pierce co has a june 30 fiscal year end. it estimated its annual property taxes to be 24000 based on last year's property tax bill and have accrued 2000 of property tax each month to marcher 31. its actual property tax assessment, received on april 30 is 25200 for the cale...

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