You drop a solid sphere of aluminum in the bucket of water that sits on the ground. The buoyant force equals the weight of water displaced: this is less than the weight of sphere, so the sphere sinks to the bottom. If you take the bucket with you on an elevator that accelerates upward, the apparent weight of the water increases and the buoyant force on the sphere increases. Could the acceleration of the elevator be great enough to make the sphere pop up out of water?