Chemistry
The Gaussian error function can be approximated for small values of x as erf(x)≈x. Suppose a silicon wafer is exposed to aluminum vapor at 1300∘ C. At what distance (in centimeters) will the concentration of Al be 35% of the surface concentration in 164 hours? Assu...
Chemistry
(a) Certain alloys such as LaNi5 can store hydrogen at room temperature. A plate of LaNi5 containing no hydrogen is placed in a chamber filled with pure hydrogen and maintained at a constant pressure. At what depth from the surface will the concentration of hydrogen be 1/2 the...
Chemistry
You wish to remove nitrogen from the near-surface region of a plate of cobalt which is 1.0 cm thick. The plate is placed in a furnace at 417∘ C where an atmosphere of H2 and NH3 reacts with the nitrogen in the cobalt and fixes the surface concentration to 111 ppm (parts ...
Chemistry
An undesirable consequence of welding steel by acetylene torch is the rise in hydrogen concentration in the metal. That hydrogen contamination embrittles the steel. The metal is typically subjected to a vacuum heat treatment to restore ductility. A steel part is placed in a va...
Chemistry
Carburization" of pure iron (Fe) is carried out at 950∘ C. It is desirable to achieve a carbon content of 0.9% at a depth of 0.1 mm below the surface. A constant supply of carbon at the surface maintains a surface concentration of 1.2%. Assuming the diffusivity of c...
psychology
hello, can you help me try to find research for sigmund freud unconscious mind thank you
Physics
There is a door that is 1.0 m wide and can rotate about a vertical axis without friction. The door’s mass is 15 kg and is free to swing open. Someone fires a 10 g bullet at 400 m/s into the exact center of the door, perpendicular to it. Find the angular velocity of the do...
Algebra
a helicopter that is 200 meters above the ground descends at a rate of 2 meters per second. The altitude of the helicopter after t seconds is given by h(t)=2000-2t. 1)give the range of this function 2)give the domain of this function.
Algebra
Joyce combines 9 atoms of hydrogen and 3 atoms of nitrogen to make 3 molecules of ammonia. write a direct variation equation which relates atoms of hydrogen to atoms of nitrogen. How many nitrogen atoms does Joyce need to form ammonia molecules using 51 hydrogen atoms?
Algebra
please help! Noah knows that his friend Ryan uses 2 small chlorine tablets each week to maintain his 10,000 gallon pool: 1)Write a direct variation equation that relates c and g, where c is the number of chlorine talets and g is pool volume in gallons. 2)How many small chlorin...
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