9. A running track that encircles a football field has six running lanes, each one meter...
9. A running track that encircles a football field has six running lanes, each one meter wide. The straight portions of the track on either side of the football field are 110 meters long. The outside ends of the track are semicircles with diameter 40 meters. What is the surface area of the running track? ( The area of a circle is A = = pi*(radius)? ) oso
Consider a cylindrical capacitor like that shown in Fig. 24.6. Let d = rb − ra be the spacing between the inner and outer conductors. (a) Let the radii of the two conductors be only slightly different, so that d << ra. Show that the result derived in Example 24.4 (Section 24.1) for the capacitance of a cylindrical capacitor then reduces to Eq. (24.2), the equation for the capacitance of a parallel-plate capacitor, with A being the surface area of...