When fossils or minerals certain unstable elements are sometimes locked into them. the proportion of these unstable elements gradually decreases over time as they decay into other materials in a predictable way. scientist use the rate at which such unstable elements decay to determine when fossils or minerals formed. the technique described above is known as

Asquare isothermal chip is of width w=5 mm on a side and is mounted in a substrate such that its side and back surfaces are well insulated; the front surface is exposed to the flow of a coolant at tinf=15 °c. from reliability considerations, the chip temperature must not exceed t=85 °c. if the coolant is air and the corresponding convection coefficient is h=200 w/m2 x k, what is the maximum allowable "power" of the chip? if the coolant is a liquid for which h=3000 w/m2 x k, what is the maximum allowable power of the chip?