Answer:
Step-by-step explanation:
submerged volume of pump = 40 x 12⁻³ ft³
density of oil = .9 x 62.4 lb ft⁻³ ( specific gravity x density of water )
mass of displaced oil = 40 x 12⁻³ x .9 x 62.4 lb
= 1.3 lb
buoyant force = 1.3 lb
weight of pump = 14.6 lb
extra force needed for balancing pump by spring
= 14.6 - 1.3
= 13.3 lb .