Ariver has a steady speed of 0.464 m/s. a student swims upstream a distance of 1.00 km and swims back to the starting point.
(a) if the student can swim at a speed of 1.08 m/s in still water, how long does the trip take?
(b) how much time is required in still water for the same length swim?

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