Calculate Buoyant Force of 2.00L Helium Balloon

[cbarker1]

Calculate the buoyant force (in N) on a 2.00 L helium balloon.

Work:

Upward is Buoyant
Downward is weight due to gravity

$$\Sigma F=0$$
$B-mg=0$
$B=mg$
$\rho=m/V$
$m=\rho*V$
$B=\rho_{fluid}*V_{fluid}*g$

I am stuck on $m=\rho*V$. Am I missing something?

 

[MarkFL]

I would use:

[box=blue]

Archimedes' principle

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Any object, wholly or partially immersed in a fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object.[/box]

So, you need only find the weight of 2.00 L of air. :)