Mechanical energy is the sum of two types of energy-kinetic energy and potential energy. Which of the following is an example of an object that has kinetic energy?
A. a snail crawling across a leaf
B. a computer monitor sitting on a desk
C. a tightly wound spring in a windup toy
D. a roller coaster car just before it goes downhill

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