A cylindrical habitat in space was proposed by G. K. O'Neill in 1974. If the habitat was 8.3 km in diameter and 28 km length would be able to have land, lakes, and multiple cities on the inside surface and clouds along its center. They would all be held in place by the rotation of the cylinder about its long axis.

How fast would the cylinder have to rotate (linear speed at the surface) to imitate the Earth's gravitational field at the walls of the cylinder?

Acarpenter builds an exterior house wall with a layer of wood 2.9 cm thick on the outside and a layer of styrofoam insulation 2.3 cm thick on the inside wall surface. the wood has k=0.080w/(m⋅k), and the styrofoam has k= 0.010 w/(m⋅k). the interior surface temperature is 19.0 ∘c , and the exterior surface temperature is -15.0 ∘c . a.)what is the temperature at the plane where the wood meets the styrofoam? celsius b.)what is the rate of heat flow per square meter through this wall? /m^2