explain the term eccentricity of an orbit. what is the eccentricity of an elliptical orbit as opposed to a perfectly circular orbit

Plss anybody know how to do this? ? i need the answers from a through d

Zeros that follow non-zeros numbers and are also to the right of a decimal point are significant

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