Tuesday
May 3, 2016

# Posts by stressedstudent

Total # Posts: 51

general chemistry
What is the radius of the largest sphere that can be placed at the center of a face-centered cubic unit cell of a cubic closest-packed array of spheres if the spheres have radius of 2.0 x 10^2 pm?
March 24, 2013

general chemistry
KCl crystallizes in a structure like NaCl. The ionic radius of Na+ is 0.525 times the ionic radius of Cl^- and 0.714 times the ionic radius of K+. What is the ratio of the density of NaCl to that of KCl?
March 24, 2013

chemistry
The equilibrium bond length of 1 H35Cl is 126 pm. What is wavelength of the required electromagnetic radiation to excite the rotational state from j=1 to j=2? The masses of 1H and 35Cl are 1.0078 amu and 34.9689 amu, respectively)
March 10, 2013

chemistry
What's the percentage of the H202 that has been consumed if you use 11.5ml of water, 3.0ml buffer, 2.5ml KI, 1.0ml starch, 1.0ml Na2S203.and 1.0ml H202
February 27, 2013

physics
electrons
February 27, 2013

general chemistry
A 1.24g sample of a hydrocarbon, when completely burned in excess of O2(g), yields 4.04g CO2 and 1.24g H20. Determine the empirical formula.
February 6, 2013

Physics
In an old house, the heating system uses radiators, which are hollow metal devices through which hot water or steam circulates. In one room the radiator has a dark color (emissitivity = 0.804). It has a temperature of 65.9 oC. The new owner of the house paints the radiator a ...
December 5, 2012

Physics
The latent heat of vaporization of H2O at body temperature (37°C) is 2.42 x 106 J/kg. To cool the body of a 77.6-kg jogger [average specific heat capacity = 3500 J/(kg C°)] by 2.78 C°, how many kilograms of water in the form of sweat have to be evaporated?
December 5, 2012

Physics
An aluminum can is filled to the brim with a liquid. The can and the liquid are heated so their temperatures change by the same amount. The can’s initial volume at 8 °C is 6.9 × 10-4 m3. The coefficient of volume expansion for aluminum is 69 × 10-6 (C°...
December 5, 2012

Physics
As the drawing shows, two thin strips of metal are bolted together at one end and have the same temperature. One is steel, and the other is aluminum. The steel strip is 0.062% longer than the aluminum strip. By how much should the temperature of the strips be increased, so ...
December 5, 2012

Physics
Which kind of pot would be better to use on a halogen cooktop? A. A shiny stainless steel pot B. A black cast iron pot C. It's equally OK to use either as long as you adjust the thickness so that the heat conduction is the same.
December 1, 2012

Physics
Assuming there is no conduction or convection operating, a cold object in a warm room: A.Radiates more energy than it absorbs B.Absorbs more energy than it radiates C.Only absorbs energy; it does not radiate because it is colder than its environment.
December 1, 2012

Physics
The igloo shown at the very start of chapter 13 is meant to keep out the cold. Which would work better: an igloo made of ice 15cm thick or an igloo made out of concrete 15cm thick? Ice Concrete
November 29, 2012

Physics
When you blow on a spoonful of soup to cool it, this is an example of: Natural convection Forced convection Conduction
November 29, 2012

Physics
A sealed box containing a chunk of ice is made of 2cm thick wood, a good thermal insulator. The air outside the box is warm. It takes the ice one hour to melt. If I had put 2cm of aluminum (a good thermal conductor) around the outside of the box, in contact with the wood, the ...
November 29, 2012

Physics
Neutron stars consist only of neutrons and have unbelievably high densities. A typical mass and radius for a neutron star might be 5.8 x 1028 kg and 1.5 x 103 m. (a) Find the density of such a star. (b) If a dime (V = 2.0 x 10-7 m3) were made from this material, how much would...
November 23, 2012

Physics
A sealed can is filled completely with methyl alcohol. Which of these materials could the can be made of so that it would not rupture when the whole system was cooled by 20 degrees Celsius? A.)Aluminum B.)Fused quartz C.)Copper D.)Any of these E.)None of these
November 23, 2012

Physics
Consider a cube of an unknown material. When heated by 10 K, each side expands by 1%. Using *only this information*, what is the ratio between the coefficent of volume expansion and the coefficient of linear expansion (i.e., beta/alpha)? Express your answer to two significant ...
November 23, 2012

math
Those two values will have the same value if put in the way you wrote it. If the equation was written like: (5+5)^3 it would yield a different amount rather than 5+5^3. So,it all depends on how the equation is written.
November 23, 2012

physics
The maximum applied force of compression that one man’s thighbone can endure without breaking is 7.6 x104 N. The minimum effective cross-sectional area of the bone is 3 x10-4 m2, its length is 0.54 m, and Young’s modulus is Y=9.4x109 N/m2. The mass of the man is 61 ...
November 12, 2012

physics
A tray is moved horizontally back and forth in simple harmonic motion at a frequency of f = 1.68 Hz. On this tray is an empty cup. Obtain the coefficient of static friction between the tray and the cup, given that the cup begins slipping when the amplitude of the motion is 2....
November 12, 2012

Physics
A flywheel is a solid disk that rotates about an axis that is perpendicular to the disk at its center. Rotating flywheels provide a means for storing energy in the form of rotational kinetic energy and are being considered as a possible alternative to batteries in electric ...
November 3, 2012

Physics
A long, thin rod is cut into two pieces, one being twice as long as the other. To the midpoint of piece A (the longer piece), piece B is attached perpendicularly, in order to form the inverted “T” shown in the drawing. The application of a net external torque causes ...
November 3, 2012

Physics
A solid circular disk has a mass of 1.67 kg and a radius of 0.144 m. Each of three identical thin rods has a mass of 0.351 kg. The rods are attached perpendicularly to the plane of the disk at its outer edge to form a three-legged stool (see the figure). Find the moment of ...
November 3, 2012

Physics
A baby turtle swings on a playground swing. If his turtle mom comes and sits with him, the period of the swing's oscillation will: a.Increase b.Decrease c.Stay the same
November 3, 2012

Physics
A pendulum consists of a small object hanging from the ceiling at the end of a string of negligible mass. The string has a length of 0.77 m. With the string hanging vertically, the object is given an initial velocity of 1.8 m/s parallel to the ground and swings upward in a ...
October 9, 2012

Physics
A pitcher throws a 0.107-kg baseball, and it approaches the bat at a speed of 31.7 m/s. The bat does 77.9 J of work on the ball in hitting it. Ignoring air resistance, determine the speed of the ball after the ball leaves the bat and is 22.7 m above the point of impact.
October 9, 2012

Physics
I eat a 500 Calorie lunch and go hiking up a mountain afterwards. Assuming that chemical energy is converted to gravitational potential energy with 50% efficiency, approximately how many miles up the mountain can I go before I need my dinner? 0.5 miles 1 mile 2 miles 3 miles 4...
October 7, 2012

Algebra II
October 2, 2012

Algebra II
subtract the two to the other side and then use the quadratic formula to factor the variables
October 2, 2012

Physics
If you suddenly multiplied the mass of Earth by a factor of 4, how would the period of a satellite change, if the radius of its orbit did not change? 4 times as long 1/4 as long 2 times as long 1/2 as long Unchanged
September 26, 2012

Physics
A satellite sitting on the ground has a weight of 5000 N. When it is placed in orbit 500 km above the surface of the Earth (which has a radius of 6380 km), which choice best describes its weight? Very small but slightly greater than zero. Zero. Still 5000 N. Slightly less than...
September 26, 2012

Physics
A massless rope passes over a massless, frictionless pulley. One end of the rope is connected to box 2, and the other end is connected to box 3. The weights of the three boxes are W1 = 50.7 N, W2 = 32.1 N, and W3 = 28.6 N. Determine the magnitude of the normal force that the ...
September 25, 2012

Physics
A train consists of 50 cars, each of which has a mass of 7.2 × 103 kg. The train has an acceleration of +7.2 × 10-2 m/s2. Ignore friction and determine the tension in the coupling (a) between the 30th and 31st cars and (b) between the 49th and 50th cars.
September 22, 2012

Physics
A man seeking to set a world record wants to tow a 110000-kg airplane along a runway by pulling horizontally on a cable attached to the airplane. The mass of the man is 70 kg, and the coefficient of static friction between his shoes and the runway is 0.76. What is the greatest...
September 22, 2012

Physics
The helicopter in the drawing is moving horizontally to the right at a constant velocity. The weight of the helicopter is W=59900 N. The lift force L generated by the rotating blade makes an angle of 21.0° with respect to the vertical. (a) What is the magnitude of the ...
September 22, 2012

Physics
A woman stands on a scale in a moving elevator. Her mass is 56.0 kg, and the combined mass of the elevator and scale is an additional 809 kg. Starting from rest, the elevator accelerates upward. During the acceleration, the hoisting cable applies a force of 9030 N. What does ...
September 22, 2012

Physics
What is the period of Earth's (nearly) circular motion around the Sun? (2*pi*r)/T 1 year (1 year)/(2*pi) (2*pi)/(1 year) 2*pi*(1 year)
September 22, 2012

Physics
The space probe Deep Space 1 was launched on October 24, 1998. Its mass was 474 kg. The goal of the mission was to test a new kind of engine called an ion propulsion drive. This engine generated only a weak thrust, but it could do so over long periods of time with the ...
September 18, 2012

Physics
You are in a hot-air balloon that, relative to the ground, has a velocity of 6.14 m/s in a direction due east. You see a hawk moving directly away from the balloon in a direction due north. The speed of the hawk relative to you is 2.44 m/s. What are (a) the magnitude and (b) ...
September 18, 2012

Physics
An electron is a subatomic particle (m = 9.11 x 10-31 kg) that is subject to electric forces. An electron moving in the +x direction accelerates from an initial velocity of +5.08 x 105 m/s to a final velocity of 2.63 x 106 m/s while traveling a distance of 0.0895 m. The ...
September 15, 2012

Physics
A golfer hits a shot to a green that is elevated 2.60 m above the point where the ball is struck. The ball leaves the club at a speed of 16.5 m/s at an angle of 30.0˚ above the horizontal. It rises to its maximum height and then falls down to the green. Ignoring air ...
September 15, 2012

Physics
A spacecraft is traveling with a velocity of v0x = 5040 m/s along the +x direction. Two engines are turned on for a time of 801 s. One engine gives the spacecraft an acceleration in the +x direction of ax = 1.04 m/s2, while the other gives it an acceleration in the +y ...
September 15, 2012

Physics
A heavy truck and a small car collide head-on. Before the collision they are going the same speed. Which of the following statements is true? (when I talk about the force and acceleration here I am talking about the *magnitude* -- don't worry about the direction, it's ...
September 15, 2012

Physics
Suppose a car is traveling at +24.8 m/s, and the driver sees a traffic light turn red. After 0.372 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...
September 11, 2012

Physics
Two rockets are flying in the same direction and are side by side at the instant their retrorockets fire. Rocket A has an initial velocity of + 6400 m/s, while rocket B has an initial velocity of + 9800 m/s. After a time t both rockets are again side by side, the displacement ...
September 11, 2012

Physics
In reaching her destination, a backpacker walks with an average velocity of 1.30 m/s, due west. This average velocity results, because she hikes for 6.22 km with an average velocity of 3.44 m/s due west, turns around, and hikes with an average velocity of 0.321 m/s due east. ...
September 11, 2012

Physics
I still am not understanding how to obtain the answer
September 10, 2012

Physics
A model rocket blasts off from the ground, rising straight upward with a constant acceleration that has a magnitude of 76.0 m/s2 for 1.90 seconds, at which point its fuel abruptly runs out. Air resistance has no effect on its flight. What maximum altitude (above the ground) ...
September 10, 2012

Physics
what does "u" stand for?
September 10, 2012

Physics
A roof tile falls from rest from the top of a building. An observer inside the building notices that it takes 0.10 s for the tile to pass her window, which has a height of 1.18 m. How far above the top of this window is the roof?
September 10, 2012

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