S

Most popular questions and responses by S
1. math

If the line 3x-4y = 0 is tangent in the first quadrant to the curve y = x^3 + k, then k is

asked on December 28, 2011
2. Physics

Suppose the surface (radius = r) of a cylindrical space station is rotating at 29.1 m/s to provide artificial gravity. What must be the value of r for the astronauts to weigh 1/3 of their earth weight? Don't know how to start please help.

asked on October 20, 2014
3. Physics

Excellent human jumpers can leap straight up to a height of 100 cm off the ground. To reach this height, with what speed would a person need to leave the ground?

asked on October 15, 2017
4. Chemistry

An aqueous solution is 8.50% ammonium chloride, NH4Cl, by mass. The density of the solution is 1.024g/mL. Calculate the molality, mole fraction, and molarity of NH4Cl in the solution. I know the formulas needed but I'm not sure where to start. M = moles

asked on January 24, 2012
5. physics

In getting ready to slam-dunk the ball, a basketball player starts from rest and sprints to a speed of 11.0 m/s in 2.58 s. Assuming that the player accelerates uniformly, determine the distance he runs.

asked on September 7, 2014
6. Physics

A tennis player strikes a ball when it is 2.20m above the ground, with a velocity 18.7 m/s at 20 degrees above the horizontal. The net is 5m away horizontally and it is 0.90m high. after 0.37 seconds, what is the direction of the ball with respect to the

asked on January 28, 2016
7. Physics

Lead has a density of 11300 kg/m^3 at 0 degrees celcius. What is the density of lead at 90 degrees celcius?

asked on November 14, 2012
8. Physics

a mass, m = 2.1 kg, is ejected horizontally from a compressed coil with a force constant, k = 5.2 N/m and compression, x = 25 cm, onto a rough ramp that is 1.5 cm long with one end raised to a height, h= 120 cm. the speed at the bottom of the rough ramp is

asked on March 3, 2016
9. Chemistry

1. [ PF4 ]+ (a) What is the electron-group geometry, according to VSEPR theory? (b) What is the molecular geometry? (c) Is this species polar or nonpolar?

asked on December 7, 2015
10. chemistry

are these right? How many atoms are there in 1.3x10^22 molecules NO2? atoms=(1.3x10^22 molecules NO2) x (2atoms/1molecule) = 2.6x10^22 atoms NO2 A 5.0g sample of O2 is in a container at STP. How many atoms of oxygen are in the container? atoms = (5.0g O2)

asked on December 14, 2008
11. Physics

A skier leaves the end of a horizontal ski jump at 22.0 m/s and falls 3.20 m before landing. Neglecting friction, how far horizontally does the skier travel in the air before landing?

asked on September 16, 2012
12. Physics

When striking, the pike, a predatory fish, can accelerate from rest to a speed of 3.6 m/s in 0.11 s . Distance?

asked on October 15, 2017
13. Physics

a block of mass 2kg moves on a frictionless inline (none of the forces on the block are shown). its initial velocity is v initial=3m/s, and it slides a vertical distance h=10m up the slope and its final velocity is v final=2m/s. find the external work done

asked on February 25, 2016
14. Physical Chemistry

15.The Rydberg constant for the Be3+ ion is 109731 cm–1. Calculate the ionization energy of a ground-state Be3+ ion. 22.How many electrons can occupy the following subshells: (a) 2s, (b) 4d, (c) 6f, (d) 6g, (e) 6h?

asked on August 8, 2017
15. Physics

A bowling ball encounters a 0.760-m vertical rise on the way back to the ball rack, as the drawing illustrates. Ignore frictional losses and assume that the mass of the ball is distributed uniformly. The translational speed of the ball is 7.83 m/s at the

asked on November 2, 2014
16. statistics

A manufacturer claims that the mean lifetime of its lithium batteries is 1400 hours. A homeowner selects 25 of these batteries and finds the mean lifetime to be 1380 hours with a standard deviation of 80 hours. Test the manufacturers claim. Use alpha =

asked on December 5, 2015
17. Math

solve: cot(2theta/3)= -sqrt3 Please help, I don't know how to start and how to set it up.

asked on September 29, 2014
18. physics

A tennis ball is shot vertically upward in an evacuated chamber inside a tower with an initial speed of 20.0 m/s at time t = 0 s. Approximately how long does it take the tennis ball to reach its maximum height?

asked on September 13, 2014
19. AP Chemistry

For the system 2SO2(g) + O2(g) 2SO3 (g), change in enthalpy is negative for the production of SO3. At a particular temperature, 8.00 moles of sulfur dioxide and 10.00 moles of sulfur trioxide are introduced into a 2.00 L container. The system is allowed to

asked on January 12, 2008
20. chemistry

The density of acetonitrile, CH3CN, is 0.786 g/mL, and the density of methanol, CH3OH, is 0.791 g/mL. A solution is made by dissolving 15.0 g of methanol in 250.0 mL of acetonitrile. Assuming that the volumes of the solute and solvent are additive, what is

asked on February 5, 2015
21. chemistry

An automobile maker has an order for 7,500 new cars to be delivered in one week. Each car must be fitted with a new hood ornament that requires 1 hour and 15 minutes to install. Assuming the factory operates on a standard workweek shift (8 hours per day

asked on August 20, 2013
22. chemistry

1.how do you calculate the specific heat of a metallic element if 314 joules of energy are needed to raise the temperature of a 50.0 g sample from 25.0 degrees c to 50.0 degrees c. 2. how do you propose a method for determining the specific heat for a

asked on October 2, 2007
23. Science

A biologist is constructing a cladogram to show the evolutionary relationships between the animals shown below. If anatomical features are used to construct the cladogram, which animal will be placed farthest from the shown animal? Animal shown: connexus.

asked on December 5, 2013
24. physics

An Olympic long jumper leaves the ground at an angle of 18.7 ° and travels through the air for a horizontal distance of 7.04 m before landing. What is the takeoff speed of the jumper?

asked on September 19, 2014
25. Physics

a stone is thrown at an angle of 30 degrees above the horizontal from the top edge of a cliff with an initial speed of 12m/s. a stop watch measures the stone's trajectory time from top of cliff to bottom to be 8s. how far out from the cliff's edge does the

asked on January 28, 2016
26. Physics

an airplane has a velocity of 499 km/h relative to the moving air. at the same time, a wind blows northward with a speed of 87 km/h relative to the earth. the airplane is moving in an easterly direction relative to the earth. find speed of airplane to

asked on January 28, 2016
27. MATH

During halftime of a football​game, a sling shot launches​ T-shirts at the crowd. A​ T-shirt is launched from a height of 33 feet with an initial upward velocity of 64 feet per second. The​ T-shirt is caught 48 feet above the field. How long will

asked on January 8, 2017
28. social studies

In what ways did each of the following contribute to the growth of democracy between 1800 and 1840? a. State constitution b. Charles River Bridge v. Warren Bridge decision c. Changes in political party procedures d. actions taken by Jackson himself

asked on November 15, 2006
29. stat

Construct a 90% confidence interval for the population mean. Assume the population has a normal distribution. A same of 15 randomly selected math majors has a grade point average of 2.86 with a standard deviation of 0.78. Round to the nearest hundredth.

asked on December 5, 2015
30. Physics , Pls help

A space station consists of two donut-shaped living chambers, A and B, that have the radii shown in the figure. As the station rotates, an astronaut in chamber A is moved 2.06 x 102 m along a circular arc. How far along a circular arc is an astronaut in

asked on October 25, 2014
31. health/science

what does the muscular system allow our bones to do

asked on February 4, 2019
32. statistics

A university dean is interested in determining the proportion of students who receive some sort of financial aid. Rather than examine the records for all students, the dean randomly selects 200 students and finds that 118 of them are receiving financial

asked on December 5, 2015
33. chemistry

Write the oxidation and reduction half-reactions for a silver-chromium voltaic cell. Identify the anode, cathode, and the direction of electron flow. Ag+ + e-  Ag Cr  Cr2+ + 2e- or Cr  Cr3+ + 3e- ????? Which is the correct equation for the

asked on June 16, 2016
34. physics

a glass lens has a convex surface with a radius 25.0 cm and a concave surface with radius 50.0 cm with the glass refraction = 1.51 calculate the focal length

asked on March 30, 2014
35. Chemistry

Is (NH4)2 CO3 ionic or covalent?

asked on January 31, 2012
36. Physics

a box of mass 7 kg is pulled up a frictionless 30 degree incline by a force of 381 N which acts parallel to the incline surface. the box has an initial speed of 5m/s and is pulled 9m. what is the speed of the box at the end of the 9m.

asked on March 3, 2016
37. math

Guests at a winter-themed party were served snowball cookies, snowman cookies, and snowflake cookies. All of the guests who ate snowball cookies also ate snowman cookies. Three-fourths of the snowball eaters did not also eat snowflake cookies. There were

asked on December 20, 2018
38. statistics help

The National Association of Realtors estimates that 23% of all homes purchased in 2004 were considered investment properties. If a sample of 800 homes sold in 2004 is obtained what is the probability that AT LEAST 175 home are going to be used as

asked on December 6, 2015
39. physics

A cylindrically shaped space station is rotating about the axis of the cylinder to create artificial gravity. The radius of the cylinder is 159 m. The moment of inertia of the station without people is 4.23 x 109 kg·m2. Suppose 299 people, with an average

asked on November 2, 2014
40. Physics

a 35 kg child slides down a 26 degree incline. the coefficient of kinetic friction is 0.33. what is her speed after sliding for 2.5 seconds starting from rest?

asked on February 13, 2016
41. Chemistry

A calorimeter, with calorimeter constant 7.31 J K–1, was used to measure the heat of reaction for mixing 100.0 mL of 0.100 M Ag+ with 100.0 mL of 0.100 M Cl–. The temperature change was +0.770 K for the 200.0 g of solution (specific heat capacity =

asked on November 21, 2017
42. math

Guests at a winter-themed party were served snowball cookies, snowman cookies, and snowflake cookies. All of the guests who ate snowball cookies also ate snowman cookies. Three-fourths of the snowball eaters did not also eat snowflake cookies. There were

asked on December 19, 2018
43. chemistry

Which compound would you expect to have the highest melting point? BeO MgO CaO SrO

asked on March 1, 2013
44. physics

A man holds a 185-N ball in his hand, with the forearm horizontal (see the figure). He can support the ball in this position because of the flexor muscle force , which is applied perpendicular to the forearm. The forearm weighs 24.3 N and has a center of

asked on October 28, 2014
45. College physics

To what temperature will 7700 J of heat raise 3.0 kg of water that is initially at 10.0 degrees C?

asked on May 6, 2010
46. Physics

In an 8.00 km race, one runner runs at a steady 12.0 km/h and another runs at 14.6 km/h

asked on October 15, 2017
47. Physics

In a 5.00 km race, one runner runs at a steady 11.3 km/h and another runs at 14.9 km/h . How long does the faster runner have to wait at the finish line to see the slower runner cross?

asked on October 15, 2017
48. Chemistry

Static charge can interfere with the production of plastic products by attracting dust and dirt. to reduce it, manufacturers expose the area to polonium-210, which has a half-life of 138 days. How much of a 25.0-g sample will remain after one year (365

asked on July 21, 2016
49. Physics

A rocket, initially at rest on the ground, accelerates straight upward from rest with constant acceleration 58.8 m/s2 . The acceleration period lasts for time 5.00 s until the fuel is exhausted. After that, the rocket is in free fall.

asked on October 15, 2017
50. math

Ryan showed Brandon the following four-digit number: 2002. He then told Brandon “I am thinking of a six-digit where I have added two ones to the original number. If you can guess my six-digit number in one guess, I’ll do your chores for a week.” What

asked on March 12, 2019
51. Physics

A 2 635-kg sailboat experiences an eastward force of 2 710 N by the ocean tide and a wind force against its sails with magnitude of 5 748 N directed toward the northwest (45° N of W). What is the direction of the resultant acceleration?

asked on February 4, 2016
52. chemistry

Air consists of 21 % oxygen, 78 % nitrogen and 1 % argon by volume. Calculate: * (a)  the partial pressures in Pa, if total pressure is 1 atm,   * (b)  the concentration in mol m–3, of each gas at 273 K,   * (c)  the average molar mass of air,

asked on November 21, 2017
53. Physics

A horizontal forces of magnitude 500N pulls two blocks of masses m1=10 kg and m2=20 kg which are connected by the light inextensible string and lying on the horizontal frictionless surface. Find the tension in the strings and acceleration of each mass when

asked on November 5, 2016
54. physics

The drawing shows a 156-kg crate hanging from the end of a steel bar (S = 8.1 x 1010 N/m2). The length of the bar is 0.117 m, and its cross-sectional area is 7.44 x 10-4 m2. Neglect the weight of the bar itself and determine (a) the shear stress on the bar

asked on November 12, 2014
55. physics

A baseball player puts a baseball on a batting tee. The baseball bat is able to deliver 400,000 W of power and is in contact with the ball for 0.70 ms and a distance of 1.4 cm. the mass of the ball is 145g. What is the average acceleration?

asked on November 7, 2012
56. physics

A 54.5 kg. skateboarder starts out with a speed of 1.90 m/s. He does +80.0 J of work on himself by pushing with his feet against the ground. In addition, friction does -265 J of work on him. In both cases, the forces doing the work are nonconservative. The

asked on November 21, 2011
57. math

square root of negative numbers?

asked on May 13, 2010
58. Physics

a 61.6 kg person on a diet stand on a bathroom scale in an elevator. to their great pleasure the scale reads 46.8 kg. what is the acceleration of the elevator? (up is positive)

asked on February 4, 2016
59. Physics

If 9.30 x 10^5 J of energy are transferred to 2.00kg of ice at 0 deg C, what is the final temperature of the system?

asked on November 14, 2012
60. chemistry

The Henry's law constant for CO2 is 3.1 x 10-2 mol/L-atm at 25°C. What pressure would be necessary in order to have a .25 M solution?

asked on February 5, 2015
61. Math

Lola is placing appetizers on plates She has 63 spring rolls and 84 cheese cubes She wants to include both appetizers on each plate Each plate must have the same number of spring rolls and cheese cubes. What is the greatest number of plates she can make

asked on September 15, 2014
62. science - chemistry

Some heat is supplied to a mixture of ice and liquid water in a closed container and the contents of the container are thoroughly mixed. If, after the addition of heat, both ice and liquid water remain: A) the temperature of the system will increase B) the

asked on December 27, 2010
63. Social Studies

Hi, I'm working on an essay and just wanted to know if anyone had an example you can find and might be willing to share with me. I looked and had no luck. Its an essay where you pretend to interview people and tell what happened in colonial South America.

asked on December 19, 2018
64. physics

Two forces 4N and 5N are inclined to each other at 30°, find the resultant force by parallelogram method

asked on September 12, 2019
65. chemistry

A gas absorbs 25kj of heat and does 12kj of work calculate (triangle) E

asked on April 16, 2013
66. physics

A 189.4 kg uniform, horizontal beam is hinged at one end and at the other is supported by a cable that is at 37 degrees to the vertical. The beam is 3.85 m long. Calculate the magnitude of the force at the hinge.

asked on December 4, 2015
67. chemistry

If not all the alum dissolves in the water before adding the Ba(NO3)2 solution, what effect will this have on the sulfate percent error determination?

asked on November 4, 2018
68. math

determine the product 800.5*(2*10^6)

asked on April 5, 2018
69. physics

A tennis ball is struck and departs from the racket horizontally with a speed of 26.4 m/s. The ball hits the court at a horizontal distance of 18.4 from the racket. How far above the court is the tennis ball when it leaves the racket?

asked on September 15, 2014
70. math

Dan made a quilt for his cousin's doll. The quilt had a 7 × 7 array of different color square patches. If each patch is 1 3 4 in long, what is the area of the whole quilt

asked on April 8, 2019
71. Chemistry

What is the solubility in grams per liter of SrSO4, in 0.23 M Na2SO4? Ksp for SrSO4 = 2.5E-7

asked on March 20, 2012
72. Math

Two parallel lines cut by a transversal can create all the following types of angles except A. Alternate interior angles B. Alternate exterior angles C. Corresponding angles D. Complementary angles

asked on January 3, 2010
73. math

A copier at the high school has a counter which tallies how many copies have been made on the machine. The counter, however, has a glitch: it always skips the digit 4. For example, the counter will jump from 23 copies to 25 copies, or from 39 copies to 50

asked on March 1, 2019
74. physics

A car is travelling around a banked curve at a constant speed of 84.0 km/h. If the radius of curvature of the path is 67.0 m, and there is no friction between the car and the surface, at what angle (in degrees) should the bank be set at, relative to the

asked on October 15, 2018
75. chemistry

can someone explain to me how to answer this: Polycarbonate plastic has a density of 1.2 g/c3. A photo frame is constructed from two 3.0 mm sheets of polycarbonate. Each sheet measures 28 cm by 22cm.What is the mass of the photo frame?

asked on October 7, 2007
76. physcs

Two newly discovered planets follow circular orbits around a star in a distant part of the galaxy. The orbital speeds of the planets are determined to be 41.8 km/s and 64.6 km/s. The slower planet's orbital period is 8.84 years. (a) What is the mass of the

asked on October 21, 2014
77. Physics

If 9.30 x 10^5 J of energy are transferred to 2.00kg of ice at 0 deg C, what is the final temperature of the system?

asked on November 15, 2012
78. Chemistry

A detergent solution has a pH of 11.63 at 25°C. What is the hydroxide-ion [OH-] concentration?

asked on February 21, 2012
79. msth

the mass of earth is 5.97*10^24 kilograms the mass of the moon is 7.34 *^22 kilograms what is the combines mass of earth ad the moon. express your answer in scientific notation

asked on April 5, 2018
80. Physics

A rocket, initially at rest on the ground, accelerates straight upward from rest with constant acceleration 58.8 m/s2 . The acceleration period lasts for time 5.00 s until the fuel is exhausted. After that, the rocket is in free fall. Max height

asked on October 15, 2017
81. chemistry

The Henry’s Law constant for N2 in water at 30 oC is 6.0 x 10-4 M/atm, calculate the solubility of nitrogen gas in water at a partial pressure of 2.5 atm

asked on February 5, 2015
82. Physics

a skier, mass 61 kg is at the top of a hill and starts down with an initial speed of 5m/s. he does no work on the way down, assume that the hill surface is frictionless. find his speed at the bottom of the hill which is 10m below the top.

asked on February 25, 2016
83. physics

A 2.20-kg ball, moving to the right at a velocity of +1.27 m/s on a frictionless table, collides head-on with a stationary 7.20-kg ball. Find the final velocities of (a) the 2.20-kg ball and of (b) the 7.20-kg ball if the collision is elastic. (c) Find the

asked on October 12, 2014
84. Physical Science

ok so i keep getting one wrong on a 4 question test and failing so can someone tell me what im getting wrong 1. What causes an electric current in a wire? A. Electric fields cause atoms to move in the wire. B. Electrons flow because of electrical

asked on March 1, 2013
85. physics

A cue ball (mass = 0.140 kg) is at rest on a frictionless pool table. The ball is hit dead center by a pool stick which applies an impulse of +1.60 N·s to the ball. The ball then slides along the table and makes an elastic head-on collision with a second

asked on December 7, 2011
86. Chemistry

High quality coal (anthracite) is almost pure carbon. The combustion of carbon to carbon dioxide releases 393 kJ per mol of carbon burnt. If 1.000 kg of anthracite is burnt: (i) How much heat is released? (ii) How much ice (in kg) at 273 K could be melted

asked on November 21, 2017
87. physics

The depth of the ocean is sometimes measured in fathoms (1 fathom = 6 feet). Distance on the surface of the ocean is sometimes measured in nautical miles (1 nautical mile = 6076 feet). The water beneath a surface rectangle 3.70 nautical miles by 2.80

asked on September 13, 2014
88. Physics

If a supersaturated sugar solution is allowed to evaporate slowly, sugar crystals form in the container. Hence, sugar molecules go from a disordered form (in solution) to a highly ordered, crystalline form. Does this process violate the second law of

asked on November 25, 2012
89. Science

Choose an ecosystem to research with regard to abiotic factors and how organisms in that particular ecosystem depend on those abiotic factors. Write a paragraph that describes the ecosystem that you selected and how organisms compete for abiotic factors

asked on October 23, 2012
90. Math

Two triangles are similar. The measure of the shortest side of the first triangle is 12 and the measure of the shortest side of the second triangle is 5. If the longest side of the first triangle measures 15, what is the measure of the longest side of the

asked on January 3, 2010
91. Physics

If you dive to 50 m below the surface of a lake, a) what is the pressure due to the water alone? b)What is the total or absolute pressure at that depth?

asked on March 13, 2008
92. Algebra

A wire is stretched from the ground to the top of an antenna tower. The wire is 15 feet long. The height of the tower is 3 feet greater than the distance d from the tower's base to the end of the wire. Find the distance d and the height of the tower.

asked on September 15, 2019
93. chemisty

The initial concentration of NO2 in a closed container is 0.750M. At equilibrium the concentration of O2 is 0.125M. What are the concentrations of NO2 and NO at equilibrium? 2NO2 (aq) ==== 2NO (aq) + O2 (aq)

asked on March 1, 2015
94. physics

A race driver has made a pit stop to refuel. After refueling, he starts from rest and leaves the pit area with an acceleration whose magnitude is 5.4 m/s2; after 4.4 s he enters the main speedway. At the same instant, another car on the speedway and

asked on September 7, 2014
95. Probability

In a random sample of students at a middle school, 24 wanted to change the mascot, and 30 wanted to keep the current mascot. Which is the best prediction for how many of the total of 1,140 students want to keep the current mascot? (a) 507 (b) 600 (c) 633

asked on July 24, 2014
96. Physics

9. In which system is heat usually transferred from the cooler part to the warmer part? a. A stove as it heats up water. b. A refrigerator that is running. c. An electric fan that is running. d. None of the above, because it is impossible to transfer heat

asked on November 19, 2012
97. math

Two friends are playing a variation of MasterMind where one friend tries to guess the three digit number that the other friend is thinking of. The rules of the game are as follows: -Digits can be repeated -Zero cannot be the first number, but zero can be

asked on February 14, 2019
98. math

While playing one day, Megan decided to build cubes out of a box of individual sugar cubes. Megan emptied the box onto the floor and using the sugar cubes as building blocks, Megan made three solid cubes with no sugar cubes left over. Each of the cubes

asked on February 14, 2019
99. math

A line and a plane are perpendicular if they intersect and if every line lying in the plane and passing through the point of intersection is perpendicular to the given line. Could someone rewrite this differently? Thx

asked on February 4, 2019
100. Chemistry

At 20.0°C the vapour pressure of pure methanol is 11.8 kPa and that of pure ethanol is 5.93 kPa. A gaseous mixture of methanol and ethanol is cooled and compressed until the first drops of liquid form at 20.0°C and a total pressure of 10.0 kPa. Assuming

asked on November 21, 2017

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