the terminal velocity of a copper ball of radius 2.0 mm falling through a tank of oil at 200 C is 6.5 cms-1 . compare the viscosity of the oil at 20oC. density of oil is 1.5 x 103 kg m-3, density of copper is 8.9 x 103 kg m-3.
Given that,
a = 2.0 mm = 2 × 10–3 m
vt = 6.5 cm/s = 6.5 × 10–2 m/s
density of oil ρ0 = 1.5 × 103 kg/m3
density of copper ρc = 8.9 × 103 kg/m3
η (for oil) = ?
At equilibrium,
viscous force + buoyant force = weight of ball
