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Posts by Maria

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physics
A Carnot refrigerator is operating between thermal reservoirs with temperatures of 27.9°C and 0.0°C. a) How much work will need to be input to extract 13.7 J of heat from the colder reservoir? b) How much work will be needed if the colder reservoir is at -15.7°C?

physics
A diesel engine works at a high compression ratio to compress air until it reaches a temperature high enough to ignite the diesel fuel. Suppose the compression ratio (ratio of volumes) of a specific diesel engine is 19 to 1. If air enters a cylinder at 1 atm and is compressed ...

physics
A closed auditorium of volume 27100 m^3 is filled with 2210 people at the beginning of a show, and the air in the space is at a temperature of 292 K and a pressure of 1.013·105 Pa. If there were no ventilation, by how much would the temperature (in K) of the air rise ...

physics
A diesel engine works at a high compression ratio to compress air until it reaches a temperature high enough to ignite the diesel fuel. Suppose the compression ratio (ratio of volumes) of a specific diesel engine is 19 to 1. If air enters a cylinder at 1 atm and is compressed ...

physics
Two copper cylinders, immersed in a water tank at 46.3°C contain helium and nitrogen, respectively. The helium-filled cylinder has a volume twice as large as the nitrogen-filled cylinder. a) Calculate the average kinetic energy of a helium molecule at 46.3°C. b) ...

physics
A closed auditorium of volume 27100 m^3 is filled with 2210 people at the beginning of a show, and the air in the space is at a temperature of 292 K and a pressure of 1.013·105 Pa. If there were no ventilation, by how much would the temperature (in K) of the air rise ...

physics
A closed auditorium of volume 27100 m^3 is filled with 2210 people at the beginning of a show, and the air in the space is at a temperature of 292 K and a pressure of 1.013·10^5 Pa. If there were no ventilation, by how much would the temperature (in K) of the air rise ...

physics
A gas expands at constant pressure from 6.25 L at 13.1°C until the volume is 7.25 L. What is the final temperature (in K) of the gas?

physics
A diesel engine works at a high compression ratio to compress air until it reaches a temperature high enough to ignite the diesel fuel. Suppose the compression ratio (ratio of volumes) of a specific diesel engine is 19 to 1. If air enters a cylinder at 1 atm and is compressed ...

physics
With each cycle, a 2650-W engine extracts 2330 J from a thermal reservoir at 85.1°C and expels 1840 J into a thermal reservoir at 20.9°C. a) What is the work done for each cycle? b) What is the engine's efficiency? c) How much time does each cycle take?

physics
Two copper cylinders, immersed in a water tank at 46.3°C contain helium and nitrogen, respectively. The helium-filled cylinder has a volume twice as large as the nitrogen-filled cylinder. a) Calculate the average kinetic energy of a helium molecule at 46.3°C. b) ...

physics
Air in a diesel engine cylinder is quickly compressed from an initial temperature of 21.1°C, an initial pressure of 1.00 atm, and an initial volume of 670 cm^3 to a final volume of 44.5 cm^3. a) Assuming the air to be an ideal diatomic gas, find the final temperature (in K...

Precalculus
I'm trying to verify the identity: (sin^2 x)/(2)= (secx-1)/(2secx)

Math
I'm sorry, but I don't understand...

physics
What is the minimum velocity needed for a roller coaster , traveling on the ground , to make it over a 112 m hill?

physics .
A roller coaster starts from rest 85m above the ground . Assume there is no energy lost when it reaches the top of the secound hill , which is 55m high. How fast is the tolerant coaster moving?

physics
Air in a diesel engine cylinder is quickly compressed from an initial temperature of 21.1°C, an initial pressure of 1.00 atm, and an initial volume of 670 cm^3 to a final volume of 44.5 cm^3. a)Assuming the air to be an ideal diatomic gas, find the final temperature (in K...

physics
a) What is the root-mean-square speed for a collection of helium-4 atoms at 311 K? b) What is the root-mean-square speed for a collection of helium-3 atoms at 311 K?

physics
A sample of gas at P = 1123 Pa, V = 1.41 L, and T = 291 K is confined in a cylinder a) Find the new pressure if the volume is reduced to half of the original volume at the same temperature. b) If the temperature is raised to 391 K in the process of part (a), what is the new ...

physics
Suppose 2 moles of an ideal gas are enclosed in a container of volume 2.70·10^4 m^3. The container is then placed in a furnace and raised to a temperature of 390 K. What is the final pressure of the gas?

physics
How much work is done to move a 6kg Christmas cake from the bottom shelf to.the refrigerator ( 0.5m high) to the top shelf (1.5m high)

Chemistry
The pH of a 0.002 50 mol/L solution of benzoic acid is 3.65. Calculate the Ka for benzoic acid.

PHI 105 critical thinking and problem solving
explaining the relationship between informative, explanatory and persuasive statements and critical thinking

nursing
The ANA'S ethical theories and principles and how it incorporates in its operations. Provide an example of how it applies these theories and principles

Math
f(x)=3/2x-4022

physics
A penny falls from a bridge. At 3.2 seconds it will have fallen ___

physics please helpp
A 1.67-kg block of aluminum at 21.7°C is to be melted and reshaped. How much heat must flow into the block in order to melt it? use the following values: For copper: c_copper=0.386 kJ/kg.K T_fusion=1359 K L_fusion=205 kg/K

physics please helpp
A copper sheet of thickness 2.09 mm is bonded to a steel sheet of thickness 1.35 mm. The outside surface of the copper sheet is held at a temperature of 100.0°C and the steel sheet at 26.3°C. a) Determine the temperature (in °C) of the copper-steel interface? b) ...

physics
A 1.67-kg block of aluminum at 21.7°C is to be melted and reshaped. How much heat must flow into the block in order to melt it? c_aluminum=0.386 kJ/kg.K T_fusion=1359 K L_fusion=205 kg/K

physics
A copper sheet of thickness 2.09 mm is bonded to a steel sheet of thickness 1.35 mm. The outside surface of the copper sheet is held at a temperature of 100.0°C and the steel sheet at 26.3°C a) Determine the temperature (in °C) of the copper-steel interface b) How ...

physics
Suppose 0.0210 kg of steam (at 100.00°C) is added to 0.210 kg of water (initially at 19.5°C.). The water is inside a copper cup of mass 48.9 g. The cup is inside a perfectly insulated calorimetry container that prevents heat flow with the outside environment. Find the ...

physics
A 1.67-kg block of aluminum at 21.7°C is to be melted and reshaped. How much heat must flow into the block in order to melt it? use the following values: For copper: c_copper=0.386 kJ/kg.K T_fusion=1359 K L_fusion=205 kg/K For aluminum: c_aluminum=0.900 kJ/kg.K T_fusion=...

physics
A 1.41-kg aluminum pot contains 2.25 L of water. Both pot and water are initially at 17.5°C. How much heat must flow into the pot and the water to bring their temperature up to 92.7°C? Assume that the effect of water evaporation during the heating process can be ...

physics
Suppose 0.0210 kg of steam (at 100.00°C) is added to 0.210 kg of water (initially at 19.5°C.). The water is inside a copper cup of mass 48.9 g. The cup is inside a perfectly insulated calorimetry container that prevents heat flow with the outside environment. Find the ...

calculus
Find the constants a & b such that the function f(x)={2 if ≤ -1 {ax+b if -1<x<3 {-2 if x ≥3 is continuous on the entire real line

epidemiology
What are some global health issues related to mexico?

physics
A 40 N force is applied to pull the desk horizontally to the right. What is the magnitude (the net force or the total force) acting on the deak ?

physics
A desk weighing 80 N rests on the floor. The coefficient of friction between the floor and the desk is 0.25. What is the frictional force between yhe desk and the surface of the floor?

nursing
What options for political influence might a person pursue in an effort to change public health policy?

chemistry
what is the osmolarity of 0.35M KBr? how to set it up.

Spanish
i believe is the last one(Escribiste Mucho en la Computadora ayer.Me duelen los dedos.) because after you been writing a lot you hand get tired, the other doesn't make any sense for me, good luck.

Probability PLEASE HELP
Tina randomly selects two distinct numbers from the set {1, 2, 3, 4, 5}, and Sergio randomly selects a number from the set {1, 2, . . . , 10}. The probability that Sergio’s number is larger than the sum of the two numbers chosen by Tina is ?

Probability PLEASE HELP
thank you very much. can u help me for other quistion pleasee

Probability PLEASE HELP
A box contains exactly five chips, three red and two white. Chips are randomly removed one at a time without replacement until all the red chips are drawn or all the white chips are drawn. What is the probability that the last chip drawn is white ?

Probability Please helpp
For each integer n ≥ 4, let an denote the base-n number 0:133n. The product a4a5 : : : a99 can be expressed as m/n! where m and n are positive integers and n is as small as possible. What is the value of m?

Probability Pțease helpp
Select numbers a and b between 0 and 1 independently and at random, and let c be their sum. Let A, B, and C be the results when a, b, and c, respectively, are rounded to the nearest integer. What is the probability that A + B = C?

Probability Pțease helpp
Tina randomly selects two distinct numbers from the set {1, 2, 3, 4, 5}, and Sergio randomly selects a number from the set {1, 2, . . . , 10}. The probability that Sergio’s number is larger than the sum of the two numbers chosen by Tina is ?

Probability
A box contains exactly five chips, three red and two white. Chips are randomly • removed one at a time without replacement until all the red chips are drawn or • all the white chips are drawn. What is the probability that the last chip drawn is white? • (

calculus
what is the derivative of x^2(x^2-4)

Optimization--PLEASE HELP!!!
At t=0, ship A is 12 miles due north of ship B. Ship A travels 12 miles/hour due south, while ship B travels 8 miles/hour due east. a. Write a function for the distance between the two ships. b. At what time are the two ships closest?

Calculuss--Optimization
Thank you so much! I appreciate it!

Calculuss--Optimization
At t=0, ship A is 12 miles due north of ship B. Ship A travels 12 miles/hour due south, while ship B travels 8 miles/hour due east. a. Write a function for the distance between the two ships. b. At what time are the two ships closest?

physics please helpp
The ends of the two rods shown in the figure are separated by 2.97 mm at 24.3 °C. The left-hand rod is brass and 1.21 m long; the right-hand rod is steel and 1.21 m long. Assuming that the outside ends of both rods rest firmly against rigid supports, at what temperature ...

chemistry
20.2 g of potassium phosphate is dissolved into 650 ml of H2O yes i so confuse i need to know what property is if is morality , osmolarity , boiling point or if are another property? thank you.

chemistry
20.2 g of potassium phosphate is dissolved into 650 ml of H2O

chemistry
25 G OF CALCIUM CHLORIDE IS DISSOLVED INTO 1500mml OF H2O. how can i set it up.

physics
The ends of the two rods shown in the figure are separated by 2.97 mm at 24.3 °C. The left-hand rod is brass and 1.21 m long; the right-hand rod is steel and 1.21 m long. Assuming that the outside ends of both rods rest firmly against rigid supports, at what temperature ...

physics
The ends of the two rods shown in the figure are separated by 2.97 mm at 24.3 °C. The left-hand rod is brass and 1.21 m long; the right-hand rod is steel and 1.21 m long. Assuming that the outside ends of both rods rest firmly against rigid supports, at what temperature ...

physics
The ends of the two rods shown in the figure are separated by 2.97 mm at 24.3 °C. The left-hand rod is brass and 1.21 m long; the right-hand rod is steel and 1.21 m long. Assuming that the outside ends of both rods rest firmly against rigid supports, at what temperature ...

physics
3.9 cm it's not true :(

physics
Your physics teacher assigned a thermometer-building project. He gave you a glass tube with an inside diameter of 1.15 mm and a receptacle at one end. He also gave you 8.97 cm^3 of mercury to pour into the tube, which filled the receptacle and some of the tube. You are to add ...

science
The heaviest invertebrate is the giant squid which can have a weight of 1.6 tons spread out over its lenght of 60 feet. What is its weight in newtons?

physics
A college student is at a concert and really wants to hear the music, so she sits between two in-phase loudspeakers, which point toward each other and are 60.8 m apart. The speakers emit sound at a frequency of 428.75 Hz. At the midpoint between the speakers, there will be ...

physics
The sound level in decibels is typically expressed as β = 10 log (I/I0), but since sound is a pressure wave, the sound level can be expressed in terms of a pressure difference. Intensity depends on the amplitude squared, so the expression is β = 20 log (P/P0), where ...

Math
subtract 15 from 17. it cancels o the left side. You're left with y/3.5=2 Now make it like a fraction y/3.5=2/1 Do the butterfly 3.5*2=7 7/1=7 7 is your answer i think.

physics
Using Newton's Law of Universal Gravitation, compare the weight of a 68.1 kg astronaut on the surface of the earth to the gravitational pull of the Earth on the same astronaut when she is on the International Space Station. Constants: Average altitude of the ISS above the ...

physics
Using Newton's Law of Universal Gravitation, compare the weight of a 68.1 kg astronaut on the surface of the earth to the gravitational pull of the Earth on the same astronaut when she is on the International Space Station. Constants: Average altitude of the ISS above the ...

physics
Using the weight equation, weight = (mass)(strength of gravity field) or Fg = mg, calculate your mass in kilograms. Constants: Strength of the gravity field near the surface of the earth, g = 9.8 m/s2. 4.448 Newtons equals one pound of force. You can find the other constants ...

physics
Using Newton's Law of Universal Gravitation, compare the effect of the Sun and the Moon on the tides. Constants: Mass of the Moon, M☽= 7.348E22 kg. Moon's semi-major axis, a☽= 3.844E8 m. You can find the other constants you will need on the Astronomy ...

physics
A college student is at a concert and really wants to hear the music, so she sits between two in-phase loudspeakers, which point toward each other and are 60.8 m apart. The speakers emit sound at a frequency of 428.75 Hz. At the midpoint between the speakers, there will be ...

physics
Using Newton's Law of Universal Gravitation, compare the gravitational pull of the Sun on the Earth to the gravitational pull of the Moon on the Earth. Constants: Mass of the Moon, M☽= 7.348E22 kg. Moon's semi-major axis, a☽= 3.844E8 m. You can find the ...

physics
A college student is at a concert and really wants to hear the music, so she sits between two in-phase loudspeakers, which point toward each other and are 60.8 m apart. The speakers emit sound at a frequency of 428.75 Hz. At the midpoint between the speakers, there will be ...

physics
The sound level in decibels is typically expressed as β = 10 log (I/I0), but since sound is a pressure wave, the sound level can be expressed in terms of a pressure difference. Intensity depends on the amplitude squared, so the expression is β = 20 log (P/P0), where ...

physics
You drop a stone down a well that is 12.37 m deep. How long is it before you hear the splash? The speed of sound in air is 343 m/s.

physics
A policeman with a very good ear and a good understanding of the Doppler effect stands on the shoulder of a freeway assisting a crew in a 40-mph work zone. He notices a car approaching that is honking its horn. As the car gets closer, the policeman hears the sound of the horn ...

ASAP ENGLISH PAPER
i am writing a paper for English the question is what ethical problems may rise in research on humans?List and describe the three principles researchers are supposed to be guided by in resolving dilemmas. I AM STUCK PLEASE HELP ME!!!!!!

Calculus--Please Help!
A 13-foot ladder is leaning against a vertical wall. If the bottom of the ladder is being pulled away at a rate of 2 feet per second, how fast is the area of the triangle formed by the wall, the ground, and the ladder changing when the bottom is 12 feet away from the wall?

Question (answer quick)
No problem =)

Question (answer quick)
I would most likely go with A.

english
The sentence "The exhibits show all different varieties of cheeses and breads..." I believe contains an error. In that sentence, since you have made the word "variety" plural, you should not have s's after cheese and and bread. In other words, it should...

College Calculus
A 13-foot ladder is leaning against a vertical wall. If the bottom of the ladder is being pulled away at a rate of 2 feet per second, how fast is the area of the triangle formed by the wall, the ground, and the ladder changing when the bottom is 12 feet away from the wall?

Calculus
find the derivative of: (x^2+y^2)^2=x^2-y^2

Calculus
find the derivative of: (x^2+y^2)^2=x^2-y^2

English
Oxymoron because it contains two contradictory words. a crime cannot be holy

math2
Dan had to complete the remaining 1/3 of his science project this week. On Monday, he completed 4/5 of the work he had left to do. What part of the entire project did Dan complete on Monday? Can you guide me on how to figure it out?

math
Dan had to complete the remaining 1/3 of his science project this week. On Monday, he completed 4/5 of the work he had left to do. What part of the entire project did Dan complete on Monday?

Math
Thank you Steve

Math
one angle of a triangle is 90 degrees. If the ratio of the legs i 1:1, what are the mesuares( in degrees) of the 2 remaining angles?

chemistry
consider C3H8+O2=CO2+H20 how much oxygen would be needed to completely burn 250g of propane

Chemistry -buffers.
**1 mole of CO2 at stp is 22.26L Pka=6.1 at 37C Solubility coefecient =0.031 mmol/LmmHg at 37 C

Chemistry -buffers.
The pH of an arterial blood sample is 7.15. upon acidification of 10 ml of the plasma 5.91ml of CO2 is produced at standard temperature and presure. Calculate-a) total CO2 in the specimen b)the individual concentration of disolved CO2(H2CO3) and HCO3- c)The partial pressure of...

Chemistry
If in an experimental reaction 32.5 mL were collected of hydrogen gas at 23.5 degrees celsius and 745.2 Torr what would be the volume corrected to STP conditions?

global healh and nursing
how and why do nurses use the epidemiology methods and data?

calculus
A rectangular beam is cut from a cylindrical log of radius 25 cm. The strength of a beam of width w and height h is proportional to wh2. (See Figure 4.70.) Find the width and height of the beam of maximum strength.

nursing
Why is epidemiology important in the study of health and disease in communities

Math
google "rule of 72"

geometry
Looking at formulas, which 2 shapes describe this relationship: the area of the 2 dimensional shape is one-fourth the surface area of the 3-demensional figure? Looking at formulas, which two figures describes this relationship: the volume of the first 3-dimensional figure is ...

physics
Find the minimum diameter of a 51.5-m-long nylon string that will stretch no more than 1.01 cm when a load of 68.9 kg is suspended from its lower end. Assume that Ynylon = 3.51·10^8 N/m2 physics - bobpursley, Saturday, October 29, 2011 at 10:32am Hookes Law: elongation...

physics
yes I know. I solved with the value of elongation 0.0101 m. and I've found diameter 0.11 ! But it's wrong :( I tried many times and i always found 0.11 diameter.. I don't know where is the problem..

physics
Find the minimum diameter of a 51.5-m-long nylon string that will stretch no more than 1.01 cm when a load of 68.9 kg is suspended from its lower end. Assume that Ynylon = 3.51·10^8 N/m2 physics - bobpursley, Saturday, October 29, 2011 at 10:32am Hookes Law: elongation...

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