A 4kg rock is dropped from 5 m. There is no friction. A) What kind of energy does it have before?

B) What kind of energy does it have after?

C) Does the energy before equal to the energy after?

D) Was work done?

E) Put the above into The Law of Conservation of Energy.

F) Solve for the speed of the object that's at the bottom. (right after the rock drops)

Afactory makes propeller drive shafts for ships. a quality assurance engineer at the factory needs to estimate the true mean length of the shafts. she randomly selects four drive shafts made at the factory, measures their lengths, and finds their sample mean to be 1000 mm. the lengths are known to follow a normal distribution whose standard deviation is 2 mm. calculate a 95% confidence interval for the true mean length of the shafts. input your answers for the margin of error, lower bound, and upper bound.