Archimedes' Principle
"When a body is partially or completely immersed in a fluid, it experiences an Upthrust equal to the weight of the fluid displaced."
$U = \rho \cdot g \cdot V_{displaced}$
Weight in Air ($W_1$):
49.00 N
Upthrust ($U$):
0.00 N
Apparent Weight ($W_2$):
49.00 N
$W_2 = W_1 - U$