The force require to keep grouper submerged is 8.207N.
According to Archimedes principle buoyant force of any object must equal to weight of fluid it displaced.
The expression for the force exerted to stay submerged in salt water is
F = F(b) - w(fish)
where F(b) = buoyant force
w(fish) = weight
now substitute w(b) for F(b)
→ F = Vρg - w(fish)
where V = volume of sea water
ρ = density of sea water
Now by Archimedes principle V = m(fish) / ρ(fish)
→ F = (m(fish) / ρ (fish) ) ρg - m(fish)g
F = (85 kg/1015 kg-m^-3) (1.025× 10³ kg-m^-3) (9.8 m/s^2)
- (85kg) × 9.8 m/s^2
F = 841.207N - 833N
F = 8.207 N
Hence, the force require to keep grouper submerged is 8.207N.
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