Carl is making a model to demonstrate the reason Earth has seasons. He has a round lamp to represent the Sun. He drew the continents on a table tennis ball to represent Earth. • What are two ways Earth needs to move in Carl’s model?

• How can Carl demonstrate Earth’s position relative to the Sun when it is summer in Australia?

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?