17. A small sphere of mass m is dropped from a great height. After it has fallen 100 m, it has attained its terminal velocity and continues to fall at that speed. The work done by air friction against the sphere during the first 100 m of fall is
(a) Greater than the work done by air friction in the second 100 m
(b) Less than the work done by air friction in the second 100 m
(c) Equal to 100 mg
(d) Greater than 100 mg
Answer-b
(11)