Question 118: Properties of Matter

Question

A water drop of radius 1 $$\mu$$m falls in a situation where the effect of buoyant force is negligible. Co-efficient of viscosity of air is 1.8 $$	imes$$ 10
$$-$$5
Nsm
$$-$$2
and its density is negligible as compared to that of water 10
6
gm
$$-$$3
. Terminal velocity of the water drop is :
(Take acceleration due to gravity = 10 ms
$$-$$2
)

Accepted Answer

$$6\pi \eta rv = mg$$
$$6\pi \eta rv = {4 \over 3}\pi {r^3}ho g$$
or $$v = {2 \over 9}{{ho {r^2}g} \over \eta } = {2 \over 9} 	imes {{{{10}^3} 	imes {{({{10}^{ - 6}})}^2} 	imes 10} \over {1.8 	imes {{10}^{ - 5}}}}$$
$$ = 123.4 	imes {10^{ - 6}}$$ m/s

Answer

145.4 $$	imes$$ 10
$$-$$6
ms
$$-$$1

Answer

118.0 $$	imes$$ 10
$$-$$6
ms
$$-$$1

Answer

132.6 $$	imes$$ 10
$$-$$6
ms
$$-$$1

Answer

123.4 $$	imes$$ 10
$$-$$6
ms
$$-$$1

Properties of Matter

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