Question

1. Most will agree that a block of steel will sink when placed in water. What can you do to make it float? (Use concepts of buoyancy)

2. What would change if we used cooking oil instead a water? How would the buoyant force change?

3. Do we experience a buoyant force exerted by the atmosphere (air around us)? Why or why not?

Answer 1

1.The standard definition of floating was first recorded by Archimedesand goes something like this: An object in a fluid experiences an upward force equal to the weight of the fluid displaced by the object. It is not very hard to shape steel like a boat in such a way that the weight of the boat has been displaced before the boat is completely underwater. The average density of a boat the combination of the steel and the air is very light compared to the average density of water. So very little of the boat actually has to submerge into the water before it has displaced the weight of the boat. So we can make steel float in that way.

2. Most oils are lighter than water, so to displace an amount equal to its weight, more volume of oil will be displaced.In other words the object will sink to a greater depth before it floats than it will in water. For oil same volume of dispalcement give the buoyant force change is less than water.

3.For buoyancy to push something up in the air, the thing has to be lighter than an equal volume of the air around it. But density of air is much less than our body density So we do not experience That.