Friday
January 20, 2017

# Posts by sarah

Total # Posts: 5,649

Chemistry
yes I need to find delta H. I calculated (45.9g)x (3.94J/g Celsius) x (8.1 Celsius), which came out to 1464.8526 Joules. How do I use this into solving for Delta H?
October 10, 2015

Chemistry
When 22.3 mL of 1.00 M AgNO3 is mixed with 21.7 mL of 1.50 M NaCl, the temperature of the mixture rises for 21.6 degrees C to 29.7 degrees C. The mass of the aqueous mixture is 45.9 grams and its specific heat capacity is 3.94 J/grams degrees C
October 10, 2015

Biology
In phylogenetics, we use the terms monophyletic, polyphyletic, and paraphyletic. What do each of these terms mean? How might the concept of shared, derived traits fit with these terms? I know what each of the terms mean. I am not sure about the second question.
October 8, 2015

Biology
What are the three conditions that must be met for natural selection to occur? What should happen if those three conditions are met? Define each type of natural selection, and describe what you expect to happen over time if these types of natural selection occur. Do these ...
October 8, 2015

Biology
Why is the Hardy-Weinberg Theorem useful for studying evolutionary change? What are the assumptions of this model? How does it work (in other words, describe the procedure which is used and how you figure out genotype frequencies)?
October 8, 2015

Science
I think 7 is b
October 7, 2015

Science
I need help with this too :/
October 7, 2015

Algebra
A 52 in. board is cut into two pieces. One piece is three times the length of the other. Find the length of the other piece.
October 7, 2015

Physics
A ball of mass 0.6 kg, initially at rest, is kicked directly toward a fence from a point 20 m away. The velocity of the ball as it leaves the kicker's foot is 17 m/s at angle of 45 degrees above the horizontal. The top of the fence is 6m high. The ball hits nothing while ...
October 6, 2015

Chemistry
I figured out I went wrong when calculating the moles of hydrogen. I used the molar mass of just one hydrogen since I was calculating the moles of one mole of hydrogen. I didn't know that I had to 2X the g/mol of hydrogen. Is there an explanation why this is?
October 5, 2015

Chemistry
Oh sorry, the question also gives this information:the 0.2041g of H2O were also produced.
October 5, 2015

Chemistry
A 0.1592g sample of a hydrocarbon upon combustion analysis produces 0.5008g CO2. Its molar mass is found in another experiment to be 70g mol. Determine the empirical formula, and its molecular formula. I completely messed up this question, and I don't know where I wen'...
October 5, 2015

World History
Thanks Reed :)
October 5, 2015

World History
I have to write a paper about the the similarities and differences of Ancient China and Persia. Anyone know any good websites I could use for research?
October 5, 2015

Algebra
A luxury car rental company charges $150 per day in addition to a flat fee of$50 for insurance. Write an equation that represents the cost, f(x), (in dollars) to rent the car for x days. This equation should be in slope-intercept form.
October 3, 2015

algebra
solve the system using elimination 2x-5y=8 x-3y=-1 please explian step by step
September 28, 2015

Chemistry
4.760 g of a substance (containing only C, H, and O) is burned in a combustion analysis apparatus. The mass of CO2 produced is 1.276×101 g, and the mass of H2O produced is 3.134 g. What is the empirical formula of the compound? I keep getting CH5O2, which is incorrect!
September 28, 2015

Calculus
Let u=f(r) and r=|x|=((x1)^2 +···|(xn)^2)^1/2. Show that􏰀 ∑ (∂u/∂xj)^2 = (f′(r))^2 Please help! it's an assignment due tomorrow
September 27, 2015

Chemistry
Q: 26.30mL of 0.1105 mol/L H3PO4 solution is neutralized by 139.50 mL of KOH. Calculate the mass of solid KOH required to prepare 500.0 mL of this solution. In the previous part of this question, it asked the concentration of KOH and I worked it out to be concentration of KOH ...
September 25, 2015

Physics
An incline is divided into 6 equal lengths. Starting from rest a ball accelerates down the incline. It takes 0.21 seconds to reach the first tape marker, a distance of 0.15 meter.
September 25, 2015

Physics
A student drops a rock from a bridge to the water 12.0 meters below. With what speed does the rock hit the water?
September 24, 2015

phyics
A car takes 11 s to go from v=0m/s to v = 22 m/s at constant acceleration. If you wish to find the distance traveled using the equation d=1/2at2, what value should you use for a? Express your answer to two significant figures and include the appropriate units. please help me ...
September 20, 2015

phyics
A dart leaves the barrel of a blowgun at a speed v. The length of the blowgun barrel is L. Assume that the acceleration of the dart in the barrel is uniform. a) Show that the dart moves inside the barrel for a time of 2L/v Express your answer in terms of the variables L and v...
September 20, 2015

Physics
Two hikers are climbing up a mountain and one throws a first aid kit up to another at an initial velocity of 11 m/s and at an angle of 62 deg above the horizontal. At the moment it is caught, the vertical speed is zero. What is the difference in height between the two climbers...
September 17, 2015

math
So take 1 2/5 and convert it into an improper fraction. Then multiply your improper fraction by 1/5 to see how much the second garden will need. Finally add the two numbers together
September 17, 2015

History
Imagine that you are Thomas Jefferson. You receive a letter from someone living in the colonies who does not understand what natural rights are, or how the King of England has violated them. Help please and thank you!
September 17, 2015

History
Life, Liberty and Pursit of happiness?!?
September 17, 2015

History
Yeah. But how would I put this in a sentence?
September 17, 2015

History
According to the Declaration of Independence, what are the three natural rights that are guaranteed to people? Can you help me with this question?
September 17, 2015

History
To be honset. I don't understand what those mean
September 17, 2015

History
Life, Liberty and the pursuit of Happiness.
September 17, 2015

History
Natural rights are rights that cannot be taken away by a government.
September 17, 2015

History
September 17, 2015

math,
A jeweler is heating a gold bar. It takes 7 joules of heat to raise the temperature of the bar 1°C. The initial temperature of the bar is 25°C. Use this information for Items 4–11. 4. Make a table that shows how many joules of heat would be required to raise the ...
September 16, 2015

Grammar
Is this correct grammar? Sarah has 6 oranges. Ted has 7 oranges. How many oranges do they have altogether?
September 16, 2015

math
A jeweler is heating a gold bar. It takes 7 joules of heat to raise the temperature of the bar 1°C. The initial temperature of the bar is 25°C. Use this information for Items 4–11. 4. Make a table that shows how many joules of heat would be required to raise the ...
September 16, 2015

algebra
A jeweler is heating a gold bar. It takes 7 joules of heat to raise the temperature of the bar 1°C. The initial temperature of the bar is 25°C. Use this information for Items 4–11. 4. Make a table that shows how many joules of heat would be required to raise the ...
September 16, 2015

Chemistry
The number of moles and the mass of oxygen formed by the decomposition of 1.252 g of mercury(II) oxide. I don't understand how to solve this, just want someone to explain. Thank you!
September 15, 2015

english
What public health issue starts the escalation of misery in top of the food chain?
September 15, 2015

U.S history\
so far I have this im not sure if this is right because im supposed to follow the outline The impact of the South Atlantic slave trade system on the British North American colonies was the way it affected the colony politically and economically. Politically the colony was ...
September 14, 2015

U.S history\
I have to make a thesis statment - Prompt: Analyze the Impact of the Atlantic System on the development of the British North American colonies during the 17th and 18th centuries. Reminder: X. However, A, B, C. Therefore, Y. Tips: X= least important cause or consequence with ...
September 14, 2015

U.S history\
how did the south atlantic slave trade not change north american colonies
September 14, 2015

history
X= least important cause or consequence with explanation why A,B, C = least important cause or consequence, with explanation why Y= your assertion statement can someone plz explain what the thesis formula means and how to use it my topic is Analyze the Impact of the Atlantic ...
September 14, 2015

english
What does frivolity mean in this sentence After a year of serious work, Mr. David's grade 8 class enjoyed the frivolity of a party.
September 13, 2015

science
Suppose you are hiking along a trail. Make a comparison between your displacement and your distance traveled. Check all that apply. -Your displacement must be less than your distance traveled. -Your displacement must be greater than your distance traveled. -Your displacement ...
September 12, 2015

math - ms sue
ms. sue i need your help
September 12, 2015

math
September 12, 2015

math
sorry, another typo, 18y should be 18x
September 12, 2015

math
sorry ignore " Write the equations and find the point of intersection." in the problem.
September 12, 2015

math
Austin is creating a new trail mix by  combining two of his best­selling blends.  A   pineapple­coconut­macadamia (pcm) mix  that sells for $18/kg&... September 12, 2015 algebra A medical rescue helicopter is flying at an average speed of 172 miles per hour toward its base hospital. At 2:42 p.m., the helicopter is 80 miles from the hospital. Use this information for Items 4–6. 4. Which equation can be used to determine m, the number of minutes it... September 10, 2015 Math Lockers are numbered with consecutive positive integers beginning with 1, and the digit 2 is used exactly 106 times (including on the last locker). What is the number of the last locker? September 4, 2015 chemistry What is the mass of 225ml of a liquid that has a density of 0.880g/ml September 4, 2015 Physical science A 70-kg man and a 50-kg woman are in a 60-kg boat when its motor fails. The man dives into the water with a horizontal speed of 3m/s in order to swim ashore. If he changes his mind, can he swim back to the boat if his swimming speed is 1m/s? If not, can the woman change the ... September 4, 2015 Statistics A list of transactions contains 100 numbers: 60 gains and 40 losses. The gains are positive numbers and the the losses are negative numbers. The units are thousands of dollars. For the 60 gains, the average is 18 and the SD is 7.5. For the losses the average is -20 and the SD... September 3, 2015 Chemistry I'm having trouble with knowing the relations between quantum numbers n, l, m(sub l), and m(sub s). Could you please explain? September 3, 2015 U.S. History I have some more. According to those who supported U.S. expansion, what would be 3 benefits of U.S. imperialism? September 2, 2015 U.S. History Can someone help me answer this questions? Why did a totalitarian regime rise in Germany in the 1930s? Explain at least three factors that led many Germans to embrace a totalitarian regime. September 2, 2015 math the following are the probabilities of selecting iteams from a bag (candy: grape ?, cherry 3/8, apple 1/4). What is the probability of selecting grape? September 1, 2015 Algbrea sapphire island is open 7 days a week the park has 8 ticket booth and each booth has a ticket seller from 10:00 AM to 5:00 PM on average ticket sellers work 30 hours per week write an equation that can be used to find t the minimum number of ticket sellers the park needs August 30, 2015 history Ok thanks August 30, 2015 history I still I don't understand so did the Europeans perceive themselves as the only people who had good military and was above everyone else. August 30, 2015 history how did the Europeans perceive themselves in the world during the1450s through the 1700s August 30, 2015 math Chicken was on sale for$7.95 per pound. Laurie bought small package that weighed 0.8 pound. How much did Laurie pay for the chicken?
August 27, 2015

Math Functions
Find the inverse function of f(x)=5 + \sqrt[3]{x}. so f^-1(x) equals...? I'm not sure how to approach this problem.
August 26, 2015

math
how do you turn a \$13.75 into an improper fraction
August 23, 2015

Chemistry
You have 75.0 mL of a 2.50 M solution of Na2CrO4 (aq). You also have 125 mL of a 2.15 M solution of AgNO3 (aq). Calculate the concentration of NO3 when the two solutions are added together.
August 22, 2015

Math
No, I don't. I just didn't think you should subtract the 1/4 from the first 6 months.
August 22, 2015

Math
When Bruce started bowling, he won 1/4 of the games he played. Within six months, he was winning 7/16 of his games. If he improves at the same rate, what fraction of his games should he expect to win after another six months? I subtracted the 1/4 from 7/16 and came up with 3/...
August 22, 2015

physics
A helicopter flies over the arctic ice pack at a constant altitude, towing an airborne 99-kg laser sensor which measures the thickness of the ice (see the drawing). The helicopter and the sensor move only in the horizontal direction and have a horizontal acceleration of ...
August 14, 2015

physics
A 14.4-kg sled is being pulled across a horizontal surface at a constant velocity. The pulling force has a magnitude of 66.9 N and is directed at an angle of 32 ° above the horizontal. Determine the coefficient of kinetic friction
August 14, 2015

Math
sin(arctan(-3pi/4))
August 10, 2015

Pre calc
You are standing at the peak of a mountain that is 14000 feet above sea level. The angle of depression from this peak to a nearby smaller peak is 4°. On your map, these two peaks are represented by points that are 1 inch apart. If each inch on your map represents 1.2 miles...
August 9, 2015

physics
A puck is moving on an air hockey table. Relative to an x, y coordinate system at time t = 0 s, the x components of the puck's initial velocity and acceleration are v0x = +3.9 m/s and ax = +1.2 m/s2. The y components of the puck's initial velocity and acceleration are ...
August 7, 2015

physics
Suppose a car is traveling at +15.0 m/s, and the driver sees a traffic light turn red. After 0.405 s has elapsed (the reaction time), the driver applies the brakes, and the car decelerates at 6.00 m/s2. What is the stopping distance of the car, as measured from the point where...
August 7, 2015

physics
(a) What is the magnitude of the average acceleration of a skier who, starting from rest, reaches a speed of 10.5 m/s when going down a slope for 3.18 s? (b) How far does the skier travel in this time?
August 7, 2015

physics
Two identical pellet guns are fired simultaneously from the edge of a cliff. These guns impart an initial speed of 44.7 m/s to each pellet. Gun A is fired straight upward, with the pellet going up and then falling back down, eventually hitting the ground beneath the cliff. Gun...
August 6, 2015

physics
A car is traveling at a constant speed of 25.5 m/s on a highway. At the instant this car passes an entrance ramp, a second car enters the highway from the ramp. The second car starts from rest and has a constant acceleration. What acceleration must it maintain, so that the two...
August 6, 2015

math
I really need help to find the answer to this question below. If possible, please show every step of the way in a detailed form so i can understand, it takes me a while to fully comprehend whats being done. Thank you so much. QUESTION: the data shown model the growth of a ...
July 27, 2015

Math
There's a question I've been having difficulty solving, and I would really appreciate if you can show he steps to how I can achieve the answer. QUESTION: The numbers 1, 4, 10, 20, and 35 are called tetrahedral numbers because they are related to a four sided shape ...
July 27, 2015

Math
There's a question I've been having difficulty solving, and I would really appreciate it if you can explain to me how I can achieve the answer. question:an above ground swimming pool in the shape of a cylinder, with diameter 5m, is filled at a constant rate to a depth ...
July 25, 2015

Math
How do you multiply 2 square roots?
July 25, 2015

English
Hi so I read the book The Impossible Rescue by Martin Sandler and I need 3 main ideas and 3 pieces of evidence for each can someone help me I am having a really hard time?
July 20, 2015

Chemistry
25cm^3 H2SO4 is neutralized by 40 cm^3 of 0.03 mol/dm^3 KOH. What is the molar concentration of H2SO4?
July 20, 2015

Math
Begins*
July 18, 2015

Math
Write an equation and for each sine function described. Each cycle behind at the origin. a) amplitude=6, period=180 b) amplitude=2, period=540
July 18, 2015

Math
Thank you so much! This was so helpful! Really appreciate it
July 18, 2015

Math
A Ferris wheel has a radius of 35m and starts at 2m above the ground. It rotates once every 53 second. a) determine the cosine equation of the graph, if the rider gets on at the lowest point. b) what is the height of the rider at 81 seconds?
July 18, 2015

Physics
What is the angle between the vectors A and B if vector A multiplied by vector B = 0.5 AB
July 15, 2015

Chemistry
If 32.6 mL of 0.240 M oxalic acid are required to titrate 48.9 mL of unknown sodium hydroxide: How many moles of acid are used in the titration? How many moles of base are used in the titration? What is the molarity of the unknown NaOh base? Please help I do not know where to ...
July 15, 2015

environment
hey, i have been selected to attend a training abroad but have to pay for travel myself. I need some good place to get travel grants for this. does anyone know where I can apply?
July 14, 2015

st joan of arc
Math from a spot 60 ft from the base of a building the angle of elevation is 48 degrees and the of elevation of the top of the antenna is 56 degrees. What is the height of the building? What is the height of the antenna?
July 10, 2015

obamoruf math
find the permeter of a parallelogram whose base is 6cm and side 5cm
July 10, 2015

english
COMMUNITY EAST HOSPITAL To call a Patient Dial Direct 395-8 Plus Room Number EMERGENCY ROOM……………….(NNN) NNN-NNNN/p> Main Number 1700 W 7th………………………395-8100 Billing Department…………...
July 9, 2015

Science
June 19, 2015

Science
June 19, 2015

Physics
Boxes A and B are in contact on a horizontal, frictionless surface. Box A has mass 21.0 kg and box B has mass 8.0 kg . A horizontal force of 100N is exerted on box A. What is the magnitude of the force that box A exerts on box B?
June 15, 2015

Physics
A grasshopper leaps into the air from the edge of a cliff at a 50 degree angle. He reaches a maximum height 6.74 cm above the top of the cliff and travels a total horizontal distance of 1.06 m. How tall is the cliff and what is the initial speed of the grasshopper?
June 12, 2015

algebra
what percentage is 90th percentile?
May 28, 2015