0
$\begingroup$

If I'm not wrong buoyancy formula is $$F_{B}=\rho gv_{sub}$$

In convection it is said that fluids with less density come up and parts with lower density ,which are cooler , go down and this cycle will continue till heat source stop supplying .

By considering buoyancy , when part of a fluid becomes less dense it should technically go down as a result of $\rho$ decreasing in $F_{B}=\rho gv_{sub}$ .

So how buoyancy is helping less dense parts rise ?

Appreciate any help!

$\endgroup$
3
$\begingroup$

Because $\rho$ here is the density of the surrounding fluid not of the hot part.

Let's say a small amount of fluid gets hot and has the density $\rho_{\text{hot}}$. It is now less dense than the surrounding fluid of density $\rho_{\text{cold}}$ which is cold. Hence its weigth which is proportionnal to $\rho_{\text{hot}}$ is less than its buoyancy force; which is proportional to $\rho_{\text{cold}}$ and it rises.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.