Who doesn't love a good espresso? But as I'm sure every great barista knows, the real key is all about permeability...As every great barista also knows, the ideal espresso shot (double, of course) is 60 ml, extracted at a brewing temperature of 94 degree C and a pressure of 9 bars, and takes 26 seconds to "pull". The standard diameter of the brewhead (and therefore of the coffee "puck" through which the water flows) is 58 mm. The "puck" is typically 7/8" thick. (A) What are the hydraulic conductivity and permeability of the ideal espresso puck? Be mindful that fluid properties (density and viscosity) are dependent on temperature, so you'll need to do some digging for the right values. (B) In the case of the overzealous home barista, a common mistake is to grind the coffee too coarse or too fine. Suppose all of the above parameters are the same, except that the result is a measly 25 ml espresso shot that takes 57 seconds to produce. What's the permeability of that puck 13 pts, and what should be changed to fix the problem?

Density of salty water as compared to the density of pure water is(a) is less(b) is always equal(c) is always more(d) may be less or more

If a spring has a k value of 100 newtons per meter and it is stretched 0.50 meters, what is the restoring force of the spring?

Search coils and credit cards. one practical way to measure magnetic field strength uses a small, closely wound coil called a search coil. the coil is initially held with its plane perpendicular to a magnetic field. the coil is then either quickly rotated a quarter-turn about a diameter or quickly pulled out of the field. (a) derive the equation relating the total charge q that flows through a search coil to the magnetic-field magnitude b. the search coil has n turns, each with area a, and the flux through the coil is decreased from its initial maximum value to zero in a time ∆t. the resistance of the coil is r, and the total charge is q = i∆t, where i is the average current induced by the change in flux. (b) in a credit card reader, the magnetic strip on the back of a credit card is rapidly “swiped” past a coil within the reader. explain, using the same ideas that underlie the operation of a search coil, how the reader can decode the information stored in the pattern of magnetization on the strip. (c) is it necessary that the credit card be “swiped” through the reader at exactly the right speed? why or why not?