Which factor determines the strength of gravity between Earth and the sun? (1) the degree of tilt of Earth's axis
(2) the distance between Earth and the sun
(3) Earth's period of rotation on its axis
(4) the strength of insolation at Earth's surface

People keep spending additional units of a particular resource on a want until their marginal benefit is  decreasing withgreater thanless thannot affected by  their marginal cost.

Acontinental polar air mass foms in

1. crust 1 the metallic layer at the earth's center 2. inner core 3 the firm layer between the crust and the asthenosphere 3. lower mantle 2 the layer surrounding the inner core 4. asthenosphere 4 the semi-solid layer between the top layer and the upper mantle 5. upper mantle 5 the layer between the asthenosphere and lower mantle 6. top layer 6 the earth's outermost layer 7. outer core 7 the hottest part of the mantle