Afrenkel defect in a crystal is formed when an atom leaves a normal site and moves to an interstitial site (a space inside the crystal). the energy of formation of the defect is e suppose a crystal has n normal sites and n' interstitial sites (n' is usually similar to n.) (a) (i) show that the multiplicity q of the state in which the crystal has n frenkel defects is given by n'n! ω- (n n)(nn)n [2 marks] (11 write down an expression for the entropy s as a function of n [2 marks] equilibrium is (b) show that, for n < < n, n', the number of frenkel defects at (nn exp-s/2kt) [4 marks] (c) explain briefly why the equilibrium number of vacancies differs from zero when the crystal is at temperature t greater than zero

Bernie drove home from a vacation in 1.5 hours. he traveled a total distance of 60 miles. what was his average speed in miles per hour? a. 60 mph b. 90 mph c. 40 mph d. 55mph

What happens in a global convection cell

Askydiver weighing 140 lb (including equipment) falls vertically downward from an altitude of 19,000 ft and opens the parachute after 18 s of free fall. assume that the force of air resistance, which is directed opposite to the velocity, is of magnitude 0.55|v| when the parachute is closed and is of magnitude 14|v| when the parachute is open, where the velocity v is measured in ft/s. assume that acceleration due to gravity has magnitude 32 ft/s/s; remember that weight is the product of mass and gravitational acceleration. (a) find the speed of the skydiver when the parachute opens. (b) find the distance fallen before the parachute opens. (c) what is the limiting velocity vl after the parachute opens? (d) determine how long the sky diver is in the air after the parachute opens. (e) plot the graph of velocity versus time from the beginning of the fall until the skydiver reaches the ground.