A small metallic sphere of diameter 2 mm and density 10.5 ~g / cm^ 3 is dropped in glycerine having viscosity 10 Poise and density 1.5 ~g / cm^ 3 respectively. The terminal velocity attained by the sphere is \_\_\_\_ cm

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Quantrex Academy · Accepted Answer

Correct answer: C. 2.0

Using Stokes' Law for terminal velocity:

v_t = \frac{2r^2g(\rho_s - \rho_f)}{9\eta}

.
Given: r = 0.1 cm, g = 1000 cm/s²,

\rho_s = 10.5

g/cm³,

\rho_f = 1.5

g/cm³, η = 10 Poise = 10 g/(cm⋅s).
Substituting:

v_t = \frac{2 \times (0.1)^2 \times 1000 \times (10.5 - 1.5)}{9 \times 10}

= \frac{2 \times 0.01 \times 1000 \times 9}{90}

= \frac{180}{90} = 2.0

cm/s.

A small metallic sphere of diameter 2 mm and density 10.5 ~g / cm^...

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