What is the weight of the brick?

Question

How much would a lead brick 2.0 in × 2.0 in × 8.0 in weigh if placed in oil with density 𐎕 = 0.93 g/cm3?

(𐎕Pb = 11.4g/cm3)

A) 0.34 kg B) 0.49 kg C) 5.5 kg D) 6 kg

Answer 1

Volume in cm^3=524.386048

V*Density of liquid displaced (.93) = .487 kg = answer B

Answer 2

The brick is 2x2x8 = 32 in^3.

This is 32 * 2.54 cm^3/in^3 = 524.4cm^3.

Now, weight per cm^3 of lead in air is 11.4g/cm^3, less .93g/cm^3 when in oil, or 10.47 g/cm^3.

Totaling, 524cm^3 * 10.47g/cm^3 = 5,490g

So, answer C.  B is the buoyancy force.