Silicon is FCC with an atom at 0,0,0 and an atom at 1/4,1/4,1/4 and a lattice parameter of 0.543 nm.
(a) How many atoms are there in this FCC unit cell?
(b) Calculate the number of atoms per unit volume based upon the unit cell.
(c) Calculate the number of atoms per unit volume based upon the density of 2.33 × 103 kg/m3.
(a) The atom at 0,0,0 in the FCC structure contributes 4 atoms to the unit cell. One atom from the corners and 3 atoms from the face centers. Associated with each atom in corner and face centered positions is another atom a distance of ¼, ¼, ¼ away. These atoms contribute 4 more atoms to the unit cell for a total of 8 atoms.
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A two-shell-eight-tube-pass heat exchanger condenses 3 kg/s of ammonia at 45ºC using 65 kg/s of water at 20ºC. If the ammonia enters as saturated vapor, leaves as saturated liquid, and has a heat of vaporization of 1078 kJ/kg, determine (a) outlet water temperature and (b) heat exchanger effectiveness.
What will be an ideal response?
General Questions: A horse pulls a cart with force 
. As a result of this force the cart accelerates with constant acceleration. The magnitude of the force that the cart exerts on the horse
A. is zero newtons.
B. equal to the magnitude of 
.
C. less than the magnitude of 
.
D. greater than the magnitude of 
.
E. cannot be determined without knowing the mass of the horse.
How does the work required to stretch a spring 2 cm compare with the work required to stretch it 1 cm?
a) same amount of work b) twice the work c) 4 times the work d) 8 times the work
A uniform meter stick is pivoted to rotate about a horizontal axis through the 25-cm mark on the stick. The stick is released from rest in a horizontal position. The rotational inertia of a uniform rod about an axis perpendicular to the rod and through the center of mass of the rod is given by (1/12)ML2. Determine the magnitude of the initial angular acceleration of the stick.
A. 17 rad/s2 B. 13 rad/s2 C. 15 rad/s2 D. 19 rad/s2 E. 23 rad/s2