6. (a) a small styrofoam bead with a mass of 18.2 g and a charge of −0.682 μc is suspended in equilibrium above the center of a large, horizontal sheet of plastic that has a uniform charge density on its surface. find the charge per unit area on the plastic sheet (in μc/m2). (b) what if? what are the magnitude and direction of the acceleration of the piece of styrofoam if its charge is doubled? (enter the magnitude in m/s2.)

Zirconium has an hcp crystal structure and a density of 6.51 g/cm3. (a) what is the volume of its unit cell in m3? (b) if the c/a ratio is 1.593, compute the values of c and a.

Which component of the earth’s atmosphere is decreased due to photosynthesis?

Two kilograms of air within a piston–cylinder assembly executes a carnot power cycle with maximum and minimum temperatures of 800 k and 300 k, respectively. the heat transfer to the air during the isothermal expansion is 60 kj. at the end of the isothermal expansion the volume is 0.4 m3. assume the ideal gas model for the air. determine the thermal efficiency, the volume at the beginning of the isothermal expansion, in m3, and the work during the adiabatic expansion, in kj.