1. the self-diffusion coefficient of h2o molecules in water is 2.26 x 10-5 cm2 s-1 at 25 oc. estimate how long it takes for an h2o molecule in water to travel: a. 1.0 cm at 25 oc b. 2.0 cm at 25 oc c. 2.0 cm at 50 oc (this one will take some creativity…) hint: the argument in the error function relationship for fick's second law [x/(2*(dt)^.5] must be a constant since the error function is constant, therefore: x = k' 2 (dt)0.5 where x is the diffusion distance and t is time and d is the diffusion constant. we can just assume k' =1 which is not actually the case but at least can us get order of magnitude estimates for diffusion distances.

Which is not a source of noise pollution? a)airplanes b)acid rain c)machines d)cars

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.

If forces acting on an object are unbalanced. true or false