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Posts by tracy

Total # Posts: 817

biology
need help with a paper from news article on human biology using scientific method?

Pre-Algebra 2
write a rule for the linear function in the table x 1, 2,3,4, f(x) -7, -10,-13,-16

acids
Which of the following bases is the weakest? (CH3)2NH , Kb = 5.1 x 10–4 ClO–, Kb = 2.9 x 10–7 SO42–, Kb = 8.3 x 10–13

applied physics
Calculate the magnitude of the torque produced by two 25N forces that are 3m apart and in opposite directions

math
simplify 15xy/35x

Physics
Lake Erie contains about 4.8 x 10^17 grams of fresh water. Assume that the lake has frozen solid and that the ice starts off at -3 C. How much energy would the lake need to absorb from the Sun to cause it to evaporate completely? Each gram of water will require 721.5 calories ...

Physics
What is the magnitude of buoyant froce acting on a 720 cm^3 toy submarine foating in fresh water? (d water=1 g/cm^3)

Physics
A spring and block is set up on frictionless tabletop. The 30N/m spring is compressed 16 centimeters and released. What is the maximum speed the 2.0 kilogram block will reach?

Physics
Lake Erie contains about 4.8 x 10^17 grams of fresh water. Assume that the lake has frozen solid and that the ice starts off at -3 C. How much energy would the lake need to absorb from the Sun to cause it to evaporate completely? Each gram of water will require 721.5 calories ...

Physics
A cylinder contains 0.1 cubic meters of gas at atmospheric pressure. This gas is allowed to expand until its pressure drops to 7800 Pa. What is the gas volume after this expansion has taken place? Is this answer right: 7800/10130 = 0.770

Physics
Use the first law of thermodynamics to determine the amount of heat change, Q, and whther it was added to or removd from the system. W=225J Delta U=600J Q=?

Physics
A spring and block is set up on frictionless tabletop. The 30N/m spring is compressed 16 centimeters and released. What is the maximum speed the 2.0 kilogram block will reach?

Physics-Is this correct?
A cylinder contains 0.1 cubic meters of gas at atmospheric pressure. This gas is allowed to expand until its pressure drops to 7800 Pa. What is the gas volume after this expansion has taken place? answer: 7800/10130 = 0.770

Physics-is this correct?
A person heats up a can of soup on a stove. If he does 250 joules of work on the soup by stirring it as the burner adds 1675 joules of heat, what is the change in its internal energy? I took 1675j - 250 j = 1425j

Physics-is this correct?
Lake Erie contains about 4.8 x 10^17 grams of fresh water. Assume that the lake has frozen solid and that the ice starts off at -3 C. How much energy would the lake need to absorb from the Sun to cause it to evaporate completely? Each gram of water will require 721.5 calories ...

Physics
Lake Erie contains about 4.8 x 10^17 grams of fresh water. Assume that the lake has frozen solid and that the ice starts off at -3 C. How much energy would the lake need to absorb from the Sun to cause it to evaporate completely? Each gram of water will require 721.5 calories ...

Physics
Which of the following statatements is correct? a. Thermos bottles keep food warm by combating heat loss through convection. b. A thick quilt is an example of an isulator with a low R value c. An object that is cool to the touch at room temperature is a poor conductor of heat ...

social studies
what happened to florida at the end of the american revolution

Chemistry
thank you Dr. Bob!

Chemistry
and for the sake of understanding.. can someone tell me what would happen if the reaction was exothermic instead of endothermic?

Chemistry
Consider this system at equilibrium. A(aq) <-> B(aq) Delta H = +750 kJ/mol .. What can be said about Q and K immediately after an increase in temperature? a] Q > K because Q increased.. b] Q>K because K decreased.. c] Q<K because Q decreased.. d] Q<K because ...

Chemistry
OHH (2.567)^2*0.637 = 4.197?! .. or was that a fail epiphany

Chemistry
Hi Dr. Bob, (3.03)^2 * 0.637 = 5.85? What would I do with the first equation that i got?

Chemistry
If someone could please be kind enough to see me through this problem? Calculate the value of Kp for the equation C(s) + CO2(g) <--> 2CO(g) Kp? Given that at a certain temperature.. C(s) + 2H2O(g) <--> CO2(g) + 2H2(g) Kp1 = 3.03 and H2(g) + CO2(g) <--> H2O(g...

Chemistry
thank you!

Chemistry
In which direction will the net reaction proceed. X(g) + Y(g) <==> Z(g) .. Kp = 1.00 at 300k for each of these sets of initial conditions? 1) [X] = [Y] = [Z] = 1.0 M a] net reaction goes to the left [this one?] b] net reaction goes to the right c] reaction is at ...

Physics
It takes 1110 calories of energy to melt a 185 gram lump of lead. What is lead's latent heat of fusion?

Physics
A lukewarm bottle containing 800 grams of water is placed in a refrigerator. How many calories of heat must be removed from that water to chill its temperature from 55 c to 4 c? Q = m(c)(delta t) Q = (100g)(1.0 c/g*c)(51c) = 40,800 Is the answer correct?

Physics
Which of the following statatements is correct? a. Thermos bottles keep food warm by combating heat loss through convection. b. A thick quilt is an example of an isulator with a low R value c. An object that is cool to the touch at room temperature is a poor conductor of heat ...

Physics
Which of the following statatements is correct? a. Thermos bottles keep food warm by combating heat loss through convection. b. A thick quilt is an example of an isulator with a low R value c. An object that is cool to the touch at room temperature is a poor conductor of heat ...

Physics
Lake Erie contains about 4.8 x 10^17 grams of fresh water. Assume that the lake has frozen solid and that the ice starts off at -3 C. How much energy would the lake need to absorb from the Sun to cause it to evaporate completely? Each gram of water will require 721.5 calories ...

Chemistry
Thank you so much Dr. Bob

Chemistry
For A+2B <-> 2C and Kc = 2.13 For 2C <-> D and Kc = 0.254 Calculate the value of equilibrium contant for the reaction D <-> A+2B I'm so sorry to bother anyone.. but am i only supposed to multiple 2.13 and 0.254 together in order to get the third value of ...

Chemistry
Thank you for proofreading!

Chemistry
At 389K, this reaction has a Kc value of 0.0682. 2X(g) + 2Y(g) <-> Z(g) .. Calculate Kp at 389K. Kp= this is what I did.. can somebody confirm or find any mistakes in my thought process? Kp = Kc(R)(T)^Delta n Delta n = (1)-(2+2) = -3 Kp = (0.0682)(0.08206)(398K)^-3 = 0....

Chemistry
ohhh it was no effect and no effect for 1 and 3 i got it

Chemistry
Ohh i understand Dr. Bob. So in terms of adding more.. would that be the same as increasing concentration? For example: S(s) + O2(g) <-> SO2 1] how will adding more S(s) shift the equilibrium? a] to the right [this?] b] to the left c] no effect 2] How will removing some ...

Chemistry
Did I answer this equilibrium question correctly? 2CO(g) + O2(g) <-> 2CO2(g) 1) How will increasing the concentration of CO shift the equilibrium? a] to the right [i chose this] b] to the left c] no effect 2] how will increasing the concentration of CO2 shift the ...

Physics
Lake Erie contains about 4.8 x 10^17 grams of fresh water. Assume that the lake has frozen solid and that the ice starts off at -3 C. How much energy would the lake need to absorb from the Sun to cause it to evaporate completely?

Physics
Which of the following statatements is correct? a. Thermos bottles keep food warm by combating heat loss through convection. b. A thick quilt is an example of an isulator with a low R value c. An object that is cool to the touch at room temperature is a poor conductor of heat ...

Physics
A lukewarm bottle containing 800 grams of water is placed in a refrigerator. How many calories of heat must be removed from the water to chill its temperature from 55 C to 4 C?

Physics
A lukewarm bottle containing 800 grams of water is placed in a refrigerator. How many calories of heat must be removed from the water to chill its temperature from 55 C to 4 C?

Physics
A person heats up a can of soup on a stove. If he does 250 Joules of work on the soup by stirring it as the burner adds 1675 Joules of heat, what is the change in its internal energy

Physics
At the lowest point in its swing, a 2.5 kilogram pendulum bob has 40 Joules of kinetic energy. How high will its swing when it reaches the highest point in its swing?

Physics
What is the magnitude of buoyant force acting on a 720 cm^3 toy submarine floating in fresh water? (D_water =1 g/cm^3)

PHYSICS
A 25,000 kilogram train is traveling down a track at 20 meters per second. A cow wanders onto the tracks 75 meters ahead of the train, causing the conductor to slam on the brakes. The rain skids to a stop. If the brakes can provide 62,500 Newtons of friction, will the ...

PHYSICS
A 7 kilogram bowling ball is dropped from a fourth story window. If each story is 3 meters high, use energy conservation (not the equations of motion) to find the ball's velocity when it strikes the ground. Ignore air resistance. 1/2 m v^2= mgh v= sqrt (2g*(3+.5)) V=sqrt(2...

accounting
FIFO

physics
a 1500kg sports car accelerates from 0 to 30 m/s in 8 seconds. Whaat is the power of its engine? Please help power= work/time= 1/2 m v^2/8 1/2(1500k)(30)^2 2/8 =168750 is this correct?

physics
A 7 kilogram bowling ball is dropped from a fourth story window. If each story is 3 meters high, use energy conservation (not the equations of motion) to find the ball's velocity when it strikes the ground. Ignore air resistance. 1/2 m v^2= mgh v= sqrt (2g*(3+.5)) V=sqrt(2...

physics
a 1500kg sports car accelerates from 0 to 30 m/s in 8 seconds. Whaat is the power of its engine? Please help power= work/time= 1/2 m v^2/8 1/2(1500k)(30)^2 2/8 =168750 is this correct?

Physics
A 7 kilogram bowling ball is dropped from a fourth story window. If each story is 3 meters high, use energy conservation (not the equations of motion) to find the ball's velocity when it strikes the ground. Ignore air resistance. 1/2 m v^2= mgh v= sqrt (2g*(3+.5)) V=sqrt(2...

PHYSICS
a 1500kg sports car accelerates from 0 to 30 m/s in 8 seconds. Whaat is the power of its engine? Please help

PHYSICS
A 7 kilogram bowling ball is dropped from a fourth story window. If each story is 3 meters high, use energy conservation (not the equations of motion) to find the ball's velocity when it strikes the ground. Ignore air resistance.

PHYSICS
A 25,000 kilogram train is traveling down a track at 20 meters per second. A cow wanders onto the tracks 75 meters ahead of the train, causing the conductor to slam on the brakes. The rain skids to a stop. If the brakes can provide 62,500 Newtons of friction, will the ...

Living ENvironment
In a hydrolysis reaction (enzyme) the bonds in substrate are weakened right always

Algebra
2= 10+z/-3

Chemistry
got it thank you!

Chemistry
In reverse osmosis, water flows out of a salt solution until the osmotic pressure of the solution equals the applied pressure. If a pressure of 58.0 bar is applied to seawater, what will be the final concentration of the seawater at 20 C when the reverse osmosis stops? ___M ...

Chemistry
OHHHHHHHHHHHHHHHHHHHHHHHHHH....... THANKS DR BOB!!!! always so helpful

Chemistry
The boiling point of an aqueous solution is 102.16 C. What is the freezing point? Dr. Bob, If you happen to answer this question, I was the one that a question earlier about how to know what Kf constant to use [water vs benzene?] and i didn't notice that it was given in ...

Chemistry
At -15.0 C, what is the maximum mass of fructose (C6H12O6) you can add to 3.00 kg of pure water and still have the solution freeze? Assume that fructose is a molecular solid and does not ionize when it dissolves in water. I'm confused on how you pick the Kf value.. Usually...

Physics
A crystal chandelier hangs in a fancy ballroom. Draw a free body diagram for the chandelier, including all vertical forcs affecting it. Please help :)

Physics
A toddler on a tricycle slowly rolls down a steep hill withour pedaling. It takes her six seconds to reach a speed of 8.1 m/s. Find the toddler's acceleration. a=v/t 8.1 m/s / 6 = 1.35 m/s^2 how far has the toddler traveled? d=vot + 1/2 at^2 (8.1)(6) + 1/2 (1.35)(6)^2 48.6...

Physics
Jamaican sprinter Usain Bolt holds the world record for the men's 100 meter dash with a time of 9.58 seconds. Another runner is training to break this record and finds that he can accelerate at a constant rate of 1.07 m/s^2. Assuming that the runner starts from rest, will ...

chemistry
DrBob222, I understand the work, however why do we use mols? aren't we trying to find the concentrations?

Physics
A 784 Newton astronaunt travels to Neptune's largest moon, Triton, with a simple bathroom scale. While standing on the surface of the moon, he finds that he now weighs only 62 Newtons. What is g, acceleration due to gravity, on Triton? g=weight/mass Is that 784/62? Sorry ...

Physics
A 784 Newton astronaunt travels to Neptune's largest moon, Triton, with a simple bathroom scale. While standing on the surface of the moon, he finds that he now weighs only 62 Newtons. What is g, acceleration due to gravity, on Triton?

world history
on july 14, 1789 a mob of people stormed a prison that held political prisoners, revolting against the injusticess of the governing party. in which country did this occur? I say France

world history
samurai

world history
Select the Japanese figure of the feudal warrior society whose role was similar to that of the knight in Medieval Europe. I say emperor

world history
I take that back its ukiyo-e

world history
What Japanese art form, meaning "pictures of the floating world," was created using woodblock prints and greatly impacted Western art, particularly Impressionists in Europe and America? I say haiku

world history
In 1962, President John F. Kennedy was faced with a decision to avoid nuclear war. What occurred to place the United States in that position? I say The Soviets placed missiles in Cuba.

world history
What Muslim country was created when India was separated due to religious conflicts? I say Pakistan

world history
What event occurred in Tiananmen Square in 1989? I say Pro-democracy protesters were killed by government troops.

world history
After World War II, Africa's economy was based on agriculture. I say false

world history
Select the nation that was created in 1947 in the Middle East to provide a homeland for Jewish people. I say Israel

world history
Which of the following is NOT true about Nelson Mandela? I say B. He led massive peaceful protests against apartheid.

world history
During the 1990s, the United States became involved in a military dispute involving which nations? I say Iraq and Kuwait

world history
In which country were apartheid laws created that prohibited interracial marriage and otherwise segregated the races? I say South Africa

world history
Which of the following nations possess nuclear weapons? I say North Korea

world history
In which country did Eva Perón work with her husband, President Juan Perón, to improve the lives of the poor and working class? I say Argentina

world history
Vietnam had been a colony controlled by what nation prior to World War II? I say France

world history
What has happened to the leadership of Cuba since Fidel Castro stepped down due to illness? I say his brother, Raul, has taken Fidel's place.

world history
North Korea's capitalist economy has surged over the last decade due to increasing exports. I say false

world history
What agreement was signed in 1992 between the United States, Mexico, and Canada? I say North American Free Trade Agreement

world history
Who came to power in China, instituting a Communist regime that would bring great suffering to the nation's people? I say Mao Zedong

world history
Which two nations rose as the world's superpowers after World War II? I say United States and the Soviet Union

world history
Why is war against terrorists difficult to fight? C. Members of terrorist groups are scattered throughout the world, so there is no one clear target. D. Terrorists leave no trace of their plans. I say C.

world history
What nation experienced the Velvet Revolution, a peaceful and non-violent movement that removed communists from power? I say Czechoslovakia

world history
Which of the following is NOT true about the arms race between the United States and the Soviet Union during the cold war? A. The Soviet Union created the first man-made satellite, prompting the United States to develop the National Aeronautics and Space Administration (NASA...

world history
To what did the U.S. Supreme Court case Brown v. Board of Education refer? A. women's rights in America B. racial segregation in American schools C. the 1960s counterculture in America D. American reaction to terrorist attacks I say B.

world history
Mikhail Gorbachev's concept of glasnost referred to an openness to communicate to the West in an attempt to pull the Soviet Union out of a poor economy. I say false

world history
In what nation did the Soviet Union place missiles, which was viewed as a threat to the United States and prompted action by President John F. Kennedy I say Cuba

world history
What is true about the key German leaders who were responsible for the Holocaust? A. The Marshall Plan provided them with the opportunity to emigrate to the United States and avoid trial. B. The Potsdam Conference, held in Potsdam, Germany, revealed that only Adolf Hitler was ...

world history
Which two superpowers engaged in an arms race during the cold war as they competed with each other to acquire advanced weaponry and build up their militaries? I say United States and the Soviet Union

world history
The Marshall Plan was enacted to support a U.S. foreign policy to keep communism from spreading, also known as. A. containment. B. deterrence. C. the Nuremberg Trials. D. NATO. I say A. CONTAINMENT

world history
soviet union

world history
which country was invaded by German forces, in spite of having signed a non-aggression pact with Germany in 1939?

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