Arock is sliding down a hill. assume that the hill is 20 meters high and the rock has a mass of 1,000 kilograms. if the rock started at the top of the hill with no initial speed, how much is its kinetic energy when it reaches the bottom of the hill? use g=10 m/s2. give the answer in kilojoules.

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