If we drop a small metal sphere into the water and watch its motion, it will quickly reach terminal velocity. If that final velocity is 5 cm/s, the radius of the sphere is 5 cm, the density of water is 1000 kg/m3, and the viscosity of the water is 10-3 Ns/m2, what is the Reynold's number of this sphere?

Question

mos1635 · Answer

I suppose you have  a relative formula....

tetyana · Answer

What do you mean?

mos1635 · Answer

a formula for the force a liquid aplieys to object mooving in ti it....?

anonymous · Answer

use the following formulae:
$$N=(\rho \times v \times D )\div \eta$$
where  $$\rho$$  is density
$$v$$ is terminal velocity.$$D$$ is diameter.$$\eta $$ is the viscocity of the liquid and N is reynold's number . find N.

mos1635 · Answer

@taufique i feel there something wrong with your initial formula....

mos1635 · Answer

N should be propotional to η

anonymous · Answer

@mos1635 no N will be inversely proportional to

anonymous · Answer

eta.

anonymous · Answer

Viscous Force F is given by
$$F = 6\pi \eta Rv$$
$$\eta$$ = coefficient of viscosity
R = radius of sphere
v = terminal velocity
From this we get 
$$\eta = F/6\pi Rv$$

ash2326 · Answer

@suyash011  would you explain more?

mos1635 · Answer

η=F/6πRv
some thing like that i had in mind too.....
but keep in mind that i have no idea who Reynold is, or his number...:) :) :)