Case Study: Floating & Sinking
During a school picnic at a lakeside, students observed:
- A small stone sank immediately.
- A football floated but remained partially immersed.
- A sealed water bottle barely floated, but when empty it floated easily.
- A heavy wooden log floated without difficulty.
Q1. Why did the small stone sink immediately?
Because its density is greater than water, so it sinks.
Q2. Why did the football float but remain partially immersed?
Its density is less than water, so it floats, but partly immersed to balance forces.
Q3. Why did the sealed water bottle barely float, but empty bottle floated easily?
Filled bottle → higher density → barely floats
Empty bottle → lower density → floats easily
Empty bottle → lower density → floats easily
Q4. Why did the heavy wooden log float?
Because wood has lower density than water.
Q5. Which principle explains these observations?
Law of Floatation: A floating body displaces liquid equal to its weight.
