17. A conductor of radius r, length and resistivity has resistance R. It is melted down and formed into a new conductor, also cylindrical, with one fourth the length of the original conductor. The resistance of the new conductor is (A)R (B)R (C)R (D)4R (E)16R

5. A solid wheel with mass M, radius R, and rotational inertia MR²/2, rolls without sliding on a horizontal surface. A horizontal force F is applied to the axle and the center of mass has an acceleration a. The magnitudes of the applied force F and the frictional force f of the surface, respectively, are: (A)F = Ma, f = 0 (B)F = Ma, f = Ma/2 (C)F = 2Ma, f = Ma (D)F = 2Ma, f = Ma/2 (E)F = 3Ma/2, f = Ma/2

17. A conductor of radius r, length and resistivity has resistance R. It is melted down and formed into a new conductor, also cylindrical, with one fourth the length of the original conductor. The resistance of the new conductor is
(A)R
(B)R
(C)R
(D)4R
(E)16R

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