In a sporting goods store you see what appears to be two identical life preservers of the same size. One is filled with Styrofoam and the other one is filled with lead pellets.
If you submerge these life preservers in the water, upon which is the buoyant force greater? Upon which is the buoyant force ineffective? Why are your answers different?
the two displace an identical volume of water. SO, the buoyant force is the same.
The lead-filled one probably weighs more than the displaced water, so it will still sink. The air-filled (styrofoam is mostly air) weighs less than the water, so it will float.
The buoyant force experienced by an object in a fluid is equal to the weight of the fluid displaced by that object. Therefore, in this scenario, we have two life preservers, one filled with Styrofoam and the other filled with lead pellets. Let's consider each case separately:
1. Life preserver filled with Styrofoam:
Styrofoam is less dense than water, so when the Styrofoam-filled life preserver is submerged in water, it displaces a volume of water that weighs more than the life preserver itself. This means that the buoyant force acting on the Styrofoam-filled life preserver is greater than its weight, causing it to float.
2. Life preserver filled with lead pellets:
Lead is denser than water, so when the lead-filled life preserver is submerged in water, it displaces a volume of water that weighs less than the life preserver itself. This means that the buoyant force acting on the lead-filled life preserver is less than its weight, making it sink.
The buoyant force is greater on the Styrofoam-filled life preserver because it displaces more water relative to its weight, while the buoyant force is ineffective on the lead-filled life preserver because it displaces less water relative to its weight.
To determine which life preserver experiences a greater buoyant force when submerged in water, we need to understand the principles of buoyancy and how they relate to the weight and volume of an object.
Buoyant force is the upward force exerted by a fluid (in this case, water) on an object. It is equal to the weight of the fluid displaced by the object. When an object is fully or partially submerged in a fluid, it experiences a buoyant force that opposes the force of gravity.
Now, let's analyze the two life preservers in question:
1. Life Preserver filled with Styrofoam:
Styrofoam is a lightweight material that is less dense than water. This means that the volume of water displaced by the Styrofoam-filled life preserver is greater than its weight. Consequently, the buoyant force experienced by the preserver is greater than its weight. This results in the life preserver floating on the surface of the water, indicating that the buoyant force is effective.
2. Life Preserver filled with Lead Pellets:
Lead is a dense material that is more dense than water. This implies that the weight of the lead-filled life preserver is greater than the volume of water it displaces. Therefore, the buoyant force experienced by the preserver is less than its weight. As a result, the life preserver sinks in water, indicating that the buoyant force is ineffective.
The key difference between the two life preservers is the density of the materials they are filled with. Styrofoam, being less dense than water, displaces a greater volume of water and experiences a greater buoyant force, causing it to float. On the other hand, lead, being more dense than water, displaces less volume of water and experiences a buoyant force lower than its weight, causing it to sink.
In summary, the buoyant force is greater on the life preserver filled with Styrofoam, and it is ineffective (less than the weight) on the life preserver filled with lead pellets.