ENGR 1500

Archimedes’ Principle and Buoyancy Assignment

1. Find the buoyant force on 2 × 10-4 m3 of iron immersed in water.

Density of water= 1000 kg/m3 ; g = 9.8 m/s2

2. Find the buoyant force on 20 kg of iron immersed in water. You may need to look up

the density of iron!

3. Find the buoyant force of 75N of copper immersed in water. You may need to look

up the density of copper!

4. A crown weighs 35N in air and 32N in water. Determine its density.

5. Consider the USS Macon, a helium-filled airship (shown below). Its envelope (the

“balloon”) contained 184,059.5 cubic meters of helium. Ignoring the small volume of

the gondola, what was the buoyancy force on this airship? If the airship weighed

108,000 kg, how much cargo could it carry? Assume the density of air is 1.225 kg

per meter cubed. The buoyancy force on an airship is due to the air in which it is

immersed.

6. A fishing boat sails from see into a river. Figures (a) and (b) below show when it is

on the sea and on the river, respectively. From the Figure, compare:

(a) Buoyant forces acting on the boat

(b) The weight of the sea water and the river water displaced by the boat

(c) The densities of the sea water and the river water

(a) Sea (b) River

7. How can a ship made of steel (ρsteel = 7.9 g/cm3) float in water?