A rain drop of radius 0.3 mm has a terminal velocity in air is 1 m/s. The viscosity of air is 8 × 10-5 poise. The viscous force on it is

Question

A rain drop of radius 0.3 mm has a terminal velocity in air is 1 m/s. The viscosity of air is 8 × 10-5 poise. The viscous force on it is (A) 45.2 × 10-4 dyne (B) 101.73 × 10-5 dyne (C) 16.95 × 10-4 dyne (D) 16.95 × 10-5 dyne

Tardigrade Admin · Accepted Answer

Radius of drop, r = 0.3 mm = 0.03 cm Terminal velocity, v = 1 m/s = 100 cm/sec Viscosity of air, η=8×10-5 poise Viscous force, f = 6 πη rv F=6×3.14×(8×10-5)×0.03×100=4.42×10-3 dyne

Q. A rain drop of radius $0.3 mm$ has a terminal velocity in air is $1 m / s$ . The viscosity of air is $8 \times 1 0^{- 5}$ poise. The viscous force on it is

$45.2 \times 1 0^{- 4}$ dyne

$101.73 \times 1 0^{- 5}$ dyne

$16.95 \times 1 0^{- 4}$ dyne

$16.95 \times 1 0^{- 5}$ dyne

Radius of drop, $r = 0.3 mm = 0.03 c m$
Terminal velocity, $v = 1 m / s = 100 c m / sec$
Viscosity of air, $η = 8 \times 1 0^{- 5}$ poise
Viscous force, $f = 6 π ηr v$
$F = 6 \times 3.14 \times (8 \times 1 0^{- 5}) \times 0.03 \times 100 = 4.42 \times 1 0^{- 3}$ dyne

Q. A rain drop of radius 0.3mm has a terminal velocity in air is 1m/s. The viscosity of air is 8×10−5 poise. The viscous force on it is

45.2×10−4 dyne

101.73×10−5 dyne

16.95×10−4 dyne

16.95×10−5 dyne