rachel

Most popular questions and responses by rachel
1. Physics

The magnitudes of the four displacement vectors shown in the drawing are A = 14.0 m, B = 11.0 m, C = 12.0 m, and D = 25.0 m. Determine the (a) magnitude and (b) direction for the resultant that occurs when these vectors are added together. Specify the

asked on September 16, 2015
2. Chemistry

3NO2(g) + H2O(l) → 2HNO3(aq) + NO(g) standard enthalpy: -133.5 Find the change in internal energy for this reaction. Enter in kJ.

asked on October 21, 2014
3. Geometry

The equation (x + 6)^2 + (y + 4)^2 = 36 models the position and range of the source of a radio signal. Describe the position of the source and the range of the signals.

asked on May 30, 2012
4. Physics

A ball is shot from the ground into the air. At a height of 9.1 m, the velocity is observed to be v = (6.6 + 5.7 ) m/s, with horizontal and upward. (a) To what maximum height does the ball rise? m (b) What total horizontal distance does the ball travel? m

asked on February 5, 2013
5. Chemistry 120

* If 13.3 kilograms of Al2O3(s), 58.4 kilograms of NaOH(l), and 58.4 kilograms of HF(g) react completely, how many kilograms of cryolite will be produced? * Which reactants will be in excess? *What is the total mass of the excess reactants left over after

asked on October 6, 2012
6. 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. Find a time that the dart moves inside the barrel. Express your answer in terms of the variables L

asked on September 19, 2015
7. chemistry

In the reaction 2SO2 (g) + O2 (g) 2SO3 (g), which change would cause the greatest increase in the concentration of SO3?

asked on May 3, 2011
8. calculus

the cross section of a 5-ft long trough is an isosceles trapezoid with a 2 foot lower base, a 3-foot upper base, and an altitude of 2 feet. water is running into the trough at a rate of 1 cubic foot per minute. how fast is the water level rising when the

asked on October 16, 2011
9. AP Calc. AB

1.If an arrow is shot upward on the moon with a velocity of 50 m/s its height (in meters) after t seconds is given by H = 50t - 0.66t2. With what velocity will the arrow hit the moon? a. -49.5 b. -47 c. -50.1 d. -50 e. -51 2.If an arrow is shot upward on

asked on September 28, 2014
10. Gen Chem 1

A tanker truck carrying 2.01×10^3kg of concentrated sulfuric acid solution tips over and spills its load. The sulfuic acid is 95.0% H2SO4 by mass and has a density of 1.84g/L. Sodium Carbonate (Na2CO3)is used to neutralize the the sulfuric acid spill. How

asked on October 6, 2010
11. Chemistry

A base has a Kb of 2.5 x 10–11. Which of the following statements is true? This is a concentrated base. This base ionizes slightly in aqueous solution. This is a strong base. An aqueous solution of this base would be acidic.

asked on March 9, 2012
12. Physics

Julie throws a ball to her friend Sarah. The ball leaves Julie's hand a distance 1.5 meters above the ground with an initial speed of 24 m/s at an angle 32 degrees; with respect to the horizontal. Sarah catches the ball 1.5 meters above the ground. What is

asked on September 3, 2013
13. Pre calc

sin(θ − ϕ); tan(θ) = 5/12 θ in Quadrant III, sin(ϕ) = − sqaure root 10/10 ϕ in Quadrant IV I tried this numerous times can somone please help me

asked on April 12, 2017
14. chemistry

Aqueous silver nitrate reacts with aqeous potassium iodide in a double-replacement reaction to produce a precipitate of silver iodide. If 34.6 ml of 0.563 M silver nitrate are used with 148.4 ml of potassium iodide: a) What molarity of potassium iodide

asked on December 6, 2011
15. Physics

A child's game consists of a block that attaches to a table with a suction cup, a spring connected to that block, a ball, and a launching ramp. By compressing the spring, the child can launch the ball up the ramp. The spring has a spring constant k, the

asked on November 7, 2008
16. Physics

A certain spring stretches 5.8cm when a load of 38N is suspended from it. How much will the spring stretch if 48N is suspended from it (and it doesn't reach its elastic limit)?

asked on November 10, 2013
17. Chem

A sealed container holding 0.0255 L of an ideal gas at 0.989 atm and 71 °C is placed into a refrigerator and cooled to 45 °C with no change in volume. Calculate the final pressure of the gas.

asked on March 7, 2018
18. Chemistry H

"When you pulled the steel wool apart, you found that the mass was unchanged. When you heated the steel wool, you found that the mass changed. Explain."

asked on August 15, 2015
19. Physics

Suppose that in the same Atwood setup another string is attached to the bottom of m1 and a constant force f is applied, retarding the upward motion of m1. If m1 = 5.30 kg and m2 = 10.60 kg, what value of f will reduce the acceleration of the system by 50%?

asked on October 24, 2009
20. Chemistry

What is the hybridization of phosphorous in a P4 molecule

asked on September 25, 2012
21. chemistry

Determine the theoretical yield of C when each of the following amounts of A and B are allowed to react in the generic reaction: A+2B-->3C 1) 1mol A; 1 mole B 2) 1mole A; 3 mole B 3) 2mole A; 2 mole B 4) 32mole A; 68 mole B

asked on November 10, 2010
22. Physical Science

A 0.6-g peanut is burned beneath 50 g of water, which increases in temperature from 22degreesC to 50 degreesc. What is the exact food value of the peanut? (Assuming a 40% efficiency)

asked on February 27, 2008
23. Chemistry

what is the name for the following coordination compounds or ions? 1. [Al(H2O)6] Br3 2. [Cr(NH3)6] Cl3 3. K3[FeF6] 4. [Zn(OH)4]-2

asked on December 4, 2008
24. Algebra

A kite is tied to the ground. The rays from the sun hit the kite perpendicular to the kite string, casting a shadow of the kite on the ground. The coordinates in the diagram are given in feet. What is the distance from where the kite is tied to the shadow?

asked on November 19, 2014
25. physics

Two very long, straight, parallel wires carry currents that are directed perpendicular. Wire 1 carries a current I1 into the page (in the -z direction) and passes through the x axis at x = +a. Wire 2 passes through the x axis at x = -2a and carries an

asked on April 9, 2011
26. physics

An accelerating voltage of 2.46 * 10^3 V is applied to an electron gun, producing a beam of electrons originally traveling horizontally north in vacuum toward the center of a viewing screen 34.0 cm away. What is the magnitude of the deflection on the

asked on April 9, 2011
27. Geometry

A gardener wants the three rosebushes in her garden to be watered by a rotating water sprinkler. The gardener draws a diagram of the garden using a grid in which each unit represents 1 ft. The rosebushes are at (1, 3), (5, 11), and (11, 4). She wants to

asked on May 20, 2012
28. Physics

A loaded penguin sled weighing 60 N rests on a plane inclined at 20° to the horizontal. Between the sled and the plane the coefficient of static friction is 0.27, and the coefficient of kinetic friction is 0.13. (a) What is the minimum magnitude of the

asked on February 19, 2013
29. Algebra 1 HELP PLEASE!

suppose P equals {0,1,2,3,4,5,6,7,8,9} and V equals {2,4,6,8,10,12,14,16,18,20}. What is P (circle) V?

asked on October 20, 2015
30. chemistry

write a net ionic equation for the following: 1)Iron (III) chloride reacts with Potassium hydroxide to produce Iron (III) oxide, Potassium chloride, and Hydrogen gas. 2)Hydrochloric acid reacts with Potassium carbonate to produce Potassium chloride,

asked on October 26, 2010
31. physics conservation of momentum

A 0.5 kg ball is thrown horizontally towards a wall with a speed of 10 m/s. The initial velocity is chosen to be the positive x-direction for this question. The ball horizontally rebounds back from the wall with a speed of 10 m/s in the negative

asked on November 8, 2008
32. chemistry

how many atoms of each element are present in five formula units of calcium permanganate?

asked on November 12, 2012
33. science

Four racecars are driving at constant speeds around a circular racetrack. The data table gives the speed of each car and each car’s distance from the center of the track at one instant. Car Speed (m/s) Position (m) A 40 20 B 40 25 C 50 20 D 50 25 Rank

asked on November 29, 2015
34. calculus

Let P= (V^2)R / (R+r)^2 Calculate dP/dr, assuming that r is variable and R is constant.

asked on September 26, 2011
35. History

1.As a result of the French and Indian War, ___ claimed all land west of the Mississippi River, and ___ gained control of all land east of it. a. Indians; Britain b. Spain; France c. France; Indians d. Spain; Britain If you have any other answers to this

asked on November 20, 2015
36. Math, Quadratic equaitons

A toy rocket is launched form a 3m platform, at 8.2m/s. The height of the rocket is modelled by the equation h=-4.0t^2+8.1t+3 where h is the height, in metres, above the ground and t is the time, in seconds. After how many seconds will the rocket rise to a

asked on November 20, 2016

The management of a private investment club has a fund of $114,000 earmarked for investment in stocks. To arrive at an acceptable overall level of risk, the stocks that management is considering have been classified into three categories: high-risk, asked on September 10, 2012 38. physics A man lifts various loads with the same lever. The distance of the applied force from the fulcrum is 2.00 m and the distance from the fulcrum to the load is 0.500 m. A graph of resistance force vs. effort force is shown. What is the mechanical advantage of asked on March 20, 2013 39. PHYSICS At the Earth's surface, a projectile is launched straight up at a speed of 8.4 km/s. To what height will it rise? Ignore air resistance and the rotation of the Earth. asked on March 11, 2011 40. Algebra 1 A pyrotechnician plans for two fireworks to explode together at the same height in the air. They travel at speeds shown at the right. Firework B is launched 0.25 s before Firework A. How many seconds after Firework B launches will both fireworks explode? asked on April 13, 2015 41. AP CALC. AB A particle moves along a line so that at time t, where 0 asked on November 16, 2014 42. Algebra After visiting the Titanic, Captain Brain and Mr. Pinky are taking the Alvin submarine back to the surface of the water. They start 1500 meters below the surface of the water, and ascend at 37 meters per hour. Note: under the water is a negative number. asked on June 25, 2016 43. Statistics A coffee company wants to make sure that there coffee is being served at the right temperature. If it is too hot, the customers could burn themselves. If it is too cold, the customers will be unsatisfied. The company has determined that they want the asked on March 15, 2012 44. Physics A small ball rolls horizontally off the edge of a tabletop of height h. It strikes the floor a distance x horizontally away from the edge of the table. (Use any variable or symbol stated above along with the following as necessary: g.) (a) How long is the asked on February 4, 2013 45. Physics Please Help ! A child throws a snowball at a tree and it sticks to the tree. Does this motion defy the Law of Conservation of Momentum? Explain. The Law of Conservation of Energy states: "If there is no net force acting on a system of objects, the total asked on November 9, 2009 46. AP Calc. AB At how many points on the curve y=4x^5-3x^4+15x^2+6 will the line tangent to the curve pass through the origin? asked on October 3, 2014 47. Chemistry Hi, I posted yesterday with this lab question. "Calculate the molar amounts of NaOH used in the reaction with the HCl solution and with the HC2H3O2. I think I got the answer to that with the help that I received. I had 5 mL of HCl, and I was using .100 M asked on April 22, 2007 48. math A test had 200 questions .Each correct answer carried 2 marks.Each wrong answer carried -1/2 marks and unanswered question fetched no marks .Ajay attempted all the question in the test and he scored 360 marks.What would his marks be, if for each correct asked on November 28, 2014 49. Physics King Kong carries Fay Wray up the 321 m tall Empire State Building. At the top of the skyscraper, Fay Wray’s shoe is knocked off with an initial upwards velocity of 5.1 and falls towards the ground. With what final velocity will the shoe be moving when asked on February 16, 2012 50. PRE-CAL Complete the table for the time t (in years) necessary for P dollars to triple when interest is compounded continuously at rate r. (Round your answers to two decimal places.) R=2% t=? tried to plug in as A=Pe^rt since continiously 3=e^.02t ? then take the asked on September 17, 2016 51. Chem A balloon is inflated to a volume of 7.0 L on a day when the atmospheric pressure is 765 mmHg. The next day, as a storm front arrives, the atmospheric pressure drops to 725 mmHg. Assuming the temperature remains constant, what is the new volume of the asked on March 6, 2018 52. Physics 1. Two points in a plane have polar coordinates (2.5 m, 30 degrees) and (3.8 m, 120 deg). Determine (a) the cartesian coordinates of both points and (b) the distance between the points. 2. Vector A has magnitude 29 units and points along +y. When vector B asked on February 17, 2014 53. chemistry The directions state "weigh about 5 grams of sodium chloride". Give minimum and maximum amounts of sodium chloride that would satisfy these instructions. asked on February 11, 2014 54. AP Chemistry (DrBob222 please help me) A sample of 1.97 grams of Z is dissolved into 500 grams of water which is in a styrofoam coffee cup. The temperature is monitored and is found to rise from 25.015◦C to 25.484◦C. What is ∆Hsolution for substance Z? Assume no asked on September 22, 2016 55. chemistry the value for the Ksp of silver chromate is reported to be 1.1 x 10^-12. in a saturated solution of silver chromate, the silver ion concentration is found to be 2.5 x 10^-4M. what must the chromate ion concentration be? asked on November 10, 2010 56. Science The water molecules now in your body were once part of a molecular cloud. Only about onemillionth of the mass of a molecular cloud is in the form of water molecules, and the mass density of such a cloud is roughly 4.0×10−21 {\rm g}/{\rm cm}^{3} Estimate asked on March 24, 2011 57. chemistry Three part question Two students each measured the density of a quartz sample three times: Student A Student B 1. 3.20g/mL 2.82g/mL 2. 2.58g/mL 2.48g/mL 3. 2.10g/mL 2.59g/mL mean 2.63g/mL 2.63 g/mL a. which student measured density with the greatest asked on February 11, 2014 58. physics Two hypothetical planets of masses m1 and m2 and radii r1 and r2, respectively, are nearly at rest when they are an infinite distance apart. Because of their gravitational attraction, they head toward each other on a collision course. Note: Both the energy asked on March 11, 2011 59. chemistry Lead is often found in Earth's crust as several lead compounds. Calculate the mass in kilograms of the amount of each of the following lead compounds that contains 4500kg of lead. 1)PbCO3 (cerussite) 2) PbSO4(anglesite) asked on October 26, 2010 60. Calculus Let g and h be any two twice-differentiable functions that are defined for all real numbers and that satisfy the following properties for all x: I) (g(x))^2 + (h(x))^2=1 ii) g'(x)= (h(x))^2 iii) h(x)>0 iv) g(0)=0 a)Justify that h'(x)=-g(x)h(x) for all x b) asked on January 30, 2014 61. pre calc To measure the height of the cloud cover at an airport, a worker shines a spotlight upward at an angle 75° from the horizontal. An observer D = 600 m away measures the angle of elevation to the spot of light to be 45°. Find the height h of the cloud asked on March 27, 2017 62. chemistry What is Delta H rxn for the following chemical reaction? H2O(l) + CCl4(l)-> COCl2(g) + 2HCl(g) asked on September 4, 2011 63. Chemistry Calculate the amount of heat required to raise the temperature of a 65-g sample of water from 32∘C to 65∘C. (The specific heat capacity of copper is 4.184 J/g∘C.) Express your answer in Joules. asked on September 19, 2015 64. Algebra Geppetto is a puppet maker. He starts the month with 3 puppets ready to sell, and makes 9 puppets per day. Write an equation to model this situation (use d for days and p for puppets). asked on June 25, 2016 65. Chemistry Calculate the pH of a buffered solution that is 0.100M in C6H5COOH (benzoic acid, Ka = 6.4 x 10-5) and 0.100M in sodium benzoate (NaC6H5COO). asked on May 5, 2010 66. math David and Peter had$90 and $200 respectively. They were each given an equal amount of money. Then Peter had twice as much money as David. How much money did each boy receive? asked on April 18, 2009 67. calcius Determine whether the function is linear, constant, or neither y = x3 - x2 + 8 a. Linear b. Constant c. Neither I think it is neither asked on June 9, 2008 68. physic Suppose a runner completes one lap around a 400-m track in a time of 50 s. Calculate the average speed of the runner. please explain process asked on September 12, 2015 69. chemistry The number of protons in an anion must always be ________ the number of electrons. the same as We can’t tell. less than greater than asked on December 6, 2014 70. calculus 2 A tomato is thrown upward from a bridge 23 m above the ground at 40 m/sec. Take the acceleration of gravity be equal to 9.8 m/s^2 (a) Give formulas for the acceleration, velocity, and height of the tomato at time t. (b) How high does the tomato go, and asked on January 28, 2013 71. chem A flexible container at an initial volume of 4.11 L contains 7.51 mol of gas. More gas is then added to the container until it reaches a final volume of 15.9 L. Assuming the pressure and temperature of the gas remain constant, calculate the number of moles asked on March 7, 2018 72. Chemistry Phosphoric acid, H3PO4(aq), is a triprotic acid, meaning that one molecule of the acid has three acidic protons. Estimate the pH, and the concentrations of all species in a 0.200 M phosphoric acid solution. pKa1 = 2.16 pKa2 = 7.21 pKa3 = 12.32 Ok I haven't asked on July 21, 2014 73. algebra The Big Screamer Coaster carries 92 people altogether. Some of its cars carry 4 passengers, and the rest carry 6 passengers. There are three less 6-passenger cars than 4-passenger cars. How many 4-passenger cars are there? asked on August 10, 2010 74. Algebra A wire 20 cm long is cut into two pieces. The longer piece is 4 cm longer than the shorter piece. Find the length of the shorter piece of wire asked on June 14, 2016 75. AP CALC At any time t=>0 , in days, the rate of growth of a bacteria population is given by y' = ky, where y is the number of bacteria present and k is a constant. The initial population is 1500 and the population quadrupled during the first two days. By what asked on April 6, 2015 76. calculus The side of a square is measured to be 12 inches with a possible error of ±0.02 inch in that measurement. If x is the exact length of the side of the square, express this difference as an absolute value inequality and solve. Then find the interval asked on August 29, 2011 77. calculus water is poured into a conical paper cup so that the height increases at the constant rate of 1 inch per second. if the cup is 6 inches tall and its top has a radius of 2 inches, how fast is the volume of water in the cup increasing when the height is 3 asked on October 16, 2011 78. life orienttion Identify six symptoms of interpersonal conflict in a person asked on February 27, 2015 79. AP Chemistry The reaction of 5.7 grams of fluorine with excess chlorine produced 7.6 grams of ClF3. What percent yield of ClF3 was obtained? Answer in units of %. asked on September 7, 2016 80. chemistry A pure copper cube has an edge length of 2.00cm. How many copper atoms does it contain? (volume of a cube = (edge length)^3; density of copper = 8.96g/cm^3 ) asked on October 26, 2010 81. math A rectangular playground is to be fenced off and divided in two by another fence parallel to one side of the playground. Five hundred and forty feet of fencing is used. Find the dimensions of the playground that maximize the total enclosed area. What is asked on December 10, 2017 82. Government What is meant by “standards of justice have not always been met”? Provide examples of some efforts that have been made to reach the goals of justice at all? asked on September 12, 2015 83. physics An object glides on a horizontal tabletop with a coefficient of kinetic friction of 0.55. If its initial velocity is 4.1 m/s, how long does it take for the object to come to rest? asked on January 28, 2012 84. Forensics Strontium-90 is a radioactive waste product from nuclear reactors. It has a half life of 29 years. How many years would it take for a quantity of strontium-90 to decay 1/16 of its original mass? asked on August 31, 2016 85. calculus Maximimum profit: you operate a tour service that offers the following rates: (1)$200 per person if 50 people (the minimum number to book the tour) go on the tour. (2) for each additional person, up to the maximum of 80 people total, everyones charge is

asked on November 27, 2011
86. Chemistry

Fish breathe the dissolved air in water through their gills. Assuming the partial pressures of oxygen and nitrogen in the air are to be .20 atm and .80 atm respectively, calculate the mole fractions of oxygen and nitrogen in the air dissolved in water at

asked on May 31, 2014
87. Physics

A small m = 2.00 g plastic ball is suspended by a L = 24.0 cm long string in a uniform electric field, as shown in Figure P15.50. If the ball is in equilibrium when the string makes a 18.0° angle with the vertical as indicated, what is the net charge on

asked on February 1, 2011
88. Geometry

Complete two column proof. Given: x/6+2=15 Prove: x=78 x/6+2=15 A:______ x/6=13 B:______ x=78 C:_______ A:a. Given b. Subtraction Property of Equality c. Division Property of Equality B:a. Given b. Addition Property of Equality c. Multiplication Property

asked on November 14, 2017
89. Physics

A pilot of mass 65 kg in a jet aircraft makes a complete vertical circle in mid-air. The vertical circle has a radius of 1.70 km at a constant speed of 215 m/s. Determine the force of the seat on the pilot at (a) the bottom of the loop and (b) the top of

asked on October 29, 2009
90. chemistry

a fish tank holds 35 gallons of water. how many pounds of water are in the fish tank?

asked on September 5, 2012
91. English 9-Please recheck answer and provide some d

I have a question about the short story "Son" by John Updike. I have research this and read it but find it very confusing-I have two answers totally eliminated and would just like some input-Thank you so much Is "Son told in a.order from the contemporary

asked on March 13, 2011
92. 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? Please help on this i don't know what i should put i think m/s squared but i

asked on September 19, 2015
93. biology

What environmental conditions would favor sexual reproduction? What environmental conditions would favor asexual reproduction? Organism - sexual reproduction - gonads asexual reproduction - honeybees - Is pillbugs an asexually organism or is a sexually

asked on April 5, 2010

Over the last 50 years, the average cost of a car has increased by a total of 1,054%. If the average cost of a car today is $31,970, how much was the average cost 50 years ago? asked on September 4, 2019 95. chem A 455-g chunk of iron is removed from an oven and plunged into 385g water in an insulated container. The temperature of the water increases from 27 degrees celsius to 89 degrees celsius. If the specific heat of iron is 0.449 J g^-1 degrees Celsius^-1, what asked on November 4, 2010 96. Calculus Line l is tangent to the graph of y= x - x²/500 at point Q & it crosses the y-axis at (0, 20) a). Find the x-coordinate of point Q b. Write an equation for line l c) Suppose the graph of y=x-x^2/500, where x and y are measured in feet, represents a hill. asked on February 15, 2014 97. chem A hot air balloon is filled with 1.51 × 106 L of an ideal gas on a cool morning (11 °C). The air is heated to 103 °C. What is the volume of the air in the balloon after it is heated? Assume that none of the gas escapes from the balloon. asked on March 6, 2018 98. Math 3 similar shirts and 4 similar jackets cost$360. 1 such shirt and 3 such jackets cost \$220. Find the cost of each shirt.

asked on February 16, 2014
99. Chem (repost)

Hydrogen and carbon dioxide react at a high temperature to give water and carbon monoxide. H2(g) + CO2(g) --> H2O(g) + CO(g) (b) Suppose 0.052 mol each of H2 and CO2 are placed in a 1.5 L container. When equilibrium is achieved at 986°C, what amounts of

asked on April 17, 2011
100. Math Literacy

I really don't know how to begin to approach this problem. A 6-year-old patient underwent an outpatient tonsillectomy and adenoidectomy The surgeon ordered 1,000 cc D5W, dispensed at a rate of 600 cc every 8 hours, to maintain hydration levels. A

asked on January 16, 2016