The terminal velocity of a copper ball of radius 5 mm falling through a tank of oil at room temperature is 10 cm s -1. If the viscosity of oil at room temperature is 0.9 kg m -1 s -1, the viscous drag force is :

Question

The terminal velocity of a copper ball of radius 5 mm falling through a tank of oil at room temperature is 10 cm s -1. If the viscosity of oil at room temperature is 0.9 kg m -1 s -1, the viscous drag force is : (A) 8.48 × 10-3 N (B) 8.48 × 10-5 N (C) 4.23 × 10-3 N (D) 4.23 × 10-6 N

Tardigrade Admin · Accepted Answer

F =6 π η rv =6 × 3.14 × 0.9 × 5 × 10-3 × 10 × 10-2 =847.8 × 10-5 N =8.48 × 10-3 N

Q. The terminal velocity of a copper ball of radius $5 mm$ falling through a tank of oil at room temperature is $10 c m s^{- 1}$ . If the viscosity of oil at room temperature is $0.9 k g m^{- 1} s^{- 1}$ , the viscous drag force is :

$8.48 \times 1 0^{- 3} N$

$8.48 \times 1 0^{- 5} N$

$4.23 \times 1 0^{- 3} N$

$4.23 \times 1 0^{- 6} N$

$F = 6 π ηr v$
$= 6 \times 3.14 \times 0.9 \times 5 \times 1 0^{- 3} \times 10 \times 1 0^{- 2}$
$= 847.8 \times 1 0^{- 5} N$
$= 8.48 \times 1 0^{- 3} N$

Q. The terminal velocity of a copper ball of radius 5mm falling through a tank of oil at room temperature is 10cms−1. If the viscosity of oil at room temperature is 0.9kgm−1s−1, the viscous drag force is :

8.48×10−3N

8.48×10−5N

4.23×10−3N

4.23×10−6N