A 55 kg snowboarder (including equipment) heads down a ski hill starting at a height of 100 m, from an initial speed of 6.3 km/h. Determine the speed she could attain by the time she arrives at the bottom of the hill if there is no friction. If she only reaches a speed of 90 km/h, what was the percentage of energy lost to friction? pls help

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