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
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(b) In the first $100 m$ body starts from rest and its velocity goes on increasing and after $100 m$ it acquire maximum velocity (terminal velocity). Further, air friction
i.e. viscous force which is proportional to velocity is low in the beginning and maximum at $v = {v_T}$.
Hence work done against air friction in the first $ 100 m$ is less than the work done in next $100 m.$
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