Physical World Units and Measurements - Result Question 22
24. The force $F$ on a sphere of radius ’ $a$ ’ is moving in a medium with velocity $v$ is given by $F=$ $6 \pi \eta$ av. The dimensions of $\eta$ are
(a) $[ML^{-3}]$
(c) $[ML^{-1}]$
(b) $[ML^{-2}]$
(d) $[ML^{-1} T^{-1}]$
[1997]
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Answer:
Correct Answer: 24. (d)
Solution:
- (d) $F=6 \pi \eta a v$
$ \eta=\frac{F}{6 \pi a v}=\frac{[MLT^{-2}]}{[L][LT^{-1}]}=[ML^{-1} T^{-1}] $
