Answer:
depth is 1.16 m
Explanation:
given data
length = 8 cm
density = 840 kg/m³
weight = 25 N
atmospheric pressure = 85 kPa
to find out
what depth in the lake will the pressure be twice the atmospheric pressure
solution
we know here that two thirds of the cube is submerged
we get first mass of cube that is
mass = 0.08³ × 0.08 = 0.43008 kg
and g = weight ÷ mass
g =
g = 58.12 m/s²
and we get now ρ for two thirds of the cube is submerged that is
weight = 0.08³ × 58.12 × ρ ×
25 = 0.08³ × 58.12 × ρ ×
ρ = 1260.18 kg/m³
pressure = ρgd ..................1
pressure = 1260.18 × 58.12 × d
85 × 10³ = 1260.18 × 58.12 × d
d = 1.16 m