Two cylindrical resistors are made of the same material and have the same resistance. The resistors, R1 and R2, have different radii, r1 and r2, and different lengths, L1 and L2. Which of the following relative values for radii and lengths would result in equal resistances?

a. r1 = r2 and L1 = 2L2
b. 2r1 = r2 and L1 = 2L2
c. r1 = r2 and 4L1 = L2
d. 2r1 = r2 and 4L1 = L2

The safe load, l, of a wooden beam of width w, height h, and length l, supported at both ends, varies directly as the product of the width and the square of the height, and inversely as the length. a wooden beam 4 inches wide, 9 inches high, and 240 inches long can hold a load of 6810 pounds. what load would a beam 3 inches wide, 8 inches high, and 144 inches long, of the same material, support? (round off your answer to the nearest integer.)