A spherical steel ball released at the top of a long column of glycerine of length L, falls through a distance with accelerated motion and the remaining distance with a uniform velocity. If and denote the times taken to cover the first and second half and W1 and W2 the work done against gravity in the two halves, then
The average velocity in the first half of the distance ; while in the second half, the average velocity is v. Therefore, . The work done against gravity in both halves .
Hence the correct choice is (d).