A) \[6.25\times {{10}^{-4}}cm\,{{s}^{-1}}\]
B) \[6.45\times {{10}^{-4}}cm\,{{s}^{-1}}\]
C) \[1.5\times {{10}^{-5}}cm\,{{s}^{-1}}\]
D) \[1.6\times {{10}^{-5}}cm\,{{s}^{-1}}\]
Correct Answer: A
Solution :
\[V\rho g=6\pi \eta rv+v{{\rho }_{\ell }}g\] \[Vg(\rho -{{\rho }_{\ell }})=6\pi \eta rv\] \[Vg(\rho -{{\rho }_{\ell }})=6\pi \eta 'rv'\] \[V'\eta '\frac{(\rho -{{\rho }_{\ell }}')}{(\rho -{{\rho }_{\ell }})}\times v\eta \] \[V'=\frac{(\rho -{{\rho }_{\ell }}')}{(\rho -{{\rho }_{\ell }})}\times \frac{v\eta }{\eta '}\] \[=\frac{(7.8-1.2)}{(7.8-1)}\times \frac{10\times 8.5\times {{10}^{-4}}}{13.2}\]\[v'=6.25\times {{10}^{-4}}cm/s.\]
You need to login to perform this action.
You will be redirected in
3 sec
