The drag force of flowing water of river on a spherical stone in the river depends only on density of the water, its flow speed and radius of the stone. Ratio of the drag forces on two spherical stone

Question

The drag force of flowing water of river on a spherical stone in the river depends only on density of the water, its flow speed and radius of the stone. Ratio of the drag forces on two spherical stones of radii 10 cm and 20 cm would be :-

TestHub · Accepted Answer

F ∝ ρ x v y r z ⇒ [ F ] = [ ρ x v y r z ] MLT − 2 = ( ML − 3 ) x ( LT − 1 ) y L z Solving by comparing exponents on both sides. F ∝ ρ v 2 r 2 For the two stones ρ and v does not change. So F ∝ r 2 Hence 1 : 4 is Ans.

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