Question

Conclusion How does the buoyant force acting on an object compare to the weight of the water displaced by that object? The wood floated; the brick did not. What condition—in terms of forces is required for an object to float? What is the condition for floating in terms of object and fluid densities? What happens to the density of water when it freezes to become ice? Which has more mass - a liter of water or a liter of ice? Oil and vinegar salad dressing settles with the oil floating on top of the vinegar. Explain in terms of density. A ship is made of steel, which is obviously denser than water. Objects that are denser than water sink. Is the density of the ship less than that of water? How can that be possible?

Answer 1

1. Buoyant force acting on a body is equal to the weight of the water displaced by the object.

b'coz buoyant force = density of water * acceleration due to gravity * vloume of water displaced by water (or volume of object sink into the water) = $\rho *g*v$ = Weight of the water displaced by the object.

2. Buoyant force acting on the block is greater than it's body weight, but in case of steel body weight is greater than buoyant force. So, main condition required to a body to float is:- Buoyant force acting on the object >= Body weight of the object.

3. Overall, density of object < density of water.

4. Density of water reduces after freezing it, b'coz on freezing water it's volume increases. So, density decreases.

5. A litre of water has more mass, b'coz density of water > density of ice.

6. Density of oil < Density of vinegar..

7. Floating of a body is combined effect of object's volume and density. So, we make the volume of ship as much large as its density became lesser in comparision to water density. Yes net density of ship < density of water. By increasing the volume of the ship.