Question

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.

Answer 1

Answer:

Here is the answer

If u find it useful....

mark it as brainiest

Answer 2

The viscosity of the oil at 20°C will be 9.92×$10^{-1}$ Ns/m²

Terminal Velocity:

The speed of a freely falling fluid(gas and liquid) is termed as terminal velocity.

Formula used:  Vt = $[\frac{2r^{2}(\rho-\sigma)g }{9\eta} ]$

To Find: viscosity (η)

              where, Vt = terminal velocity

                          r = radius

                          ρ = density of copper

                          σ = density of oil

                          g = acc. due to gravity

                         η = viscosity

Therefore, 0.065 = $[\frac{2\times 0.002^{2}(8.9\times 10^{3} - 1.5 \times 10^{3} )\times 10 }{9\times \eta} ]$

solving this, we get η = 0.992 Ns/$m^{2}$

Hence, the viscosity of oil will be 0.092 Ns/m²