1. Unprotected exposure to the sun's rays is a factor in the development of skin cancer. Which of the following is an example of empirical evidence that supports this
hypothesis?
A. a model of a skin cell showing where DNA is in the cell.
B. a skin cancer survivor's recollection that he had a bad sunburn as a child.
C. an advertisement for a sun block product that claims it protects skin against ultraviolet
rays.
D. data demonstrating a relationship between the amount of sun exposure and incidences
of skin cancer.

What is the stall speed at sea level of an airplane that weights 10000 lbs., has a wing area of 300ft^2, and a maximum lift coefficient of 1.4? what is the stall speed if flaps that double cl,max are applied?

An automobile steering wheel is shown. what is the ideal mechanical advantage? if the ama is 8, what is the efficiency of the steering wheel?

Asheet of steel 1.5 mm thick has nitrogen atmospheres on both sides at 1200oc and is permitted to achieve a steady-state diffusion condition. the diffusion coefficient for nitrogen in steel at this temperature is 6 x 10- 11 m2 /s, and the diffusion flux is found to be 1.2 x 10-7 kg/m2 -s. also, it is known that the concentration of nitrogen in the steel at the high-pressure surface is 4 kg/m3 . how far into the sheet from this high-pressure side will the concentration be 2.0 kg/m3 ? assume a linear concentration profile.