Physics

Problem

5. A ball falls straight down through the air under the influence of gravity. There is a retarding force F on the ball with magnitude given by

\mathrm{F}=b v

, where

v

is the speed of the ball and

b

is a positive constant. The ball reaches a terminal velocity after a time

t

. The magnitude of the acceleration at time

t / 2

is (A) Increasing (B) Decreasing (C)

10 \mathrm{~m} / \mathrm{s} / \mathrm{s}

(D) Zero (A) Increasing (B) Decreasing (C)

10 \mathrm{~m} / \mathrm{s} / \mathrm{s}

(D) Zero