What is the principle of floatation articulated by Archimedes?

• Any object submerged in a liquid experiences an upward buoyant force.
• An object floats if it displaces a volume of liquid equal to its weight.
• An object with density less than the liquid’s density will float.

Fill in the blank: An object will float if its density is less than or equal to the ___ density.

Liquid's

True or False: A stone floats on water because its density is less than that of water.

False. A stone sinks because its density is greater than that of water.

Fill in the blank: The average density of an object must be less than the fluid's average density for it to ___.

Float

Describe the relationship between real weight and upthrust when an object is submerged in a fluid.

• If upthrust = weight, the body floats at equilibrium.

• If upthrust < weight, the body sinks.

• If upthrust > weight, the body rises until balance is reached.

True or False: The center of buoyancy is where the weight of the object is exerted downward.

False. The center of buoyancy is where the upthrust acts upward on the body.

What role does the center of gravity play in floatation?

• For stable floatation, the body’s center of gravity (G) must lie below the metacenter (M).

• This ensures the body returns to its original position when tilted.

Fill in the blank: A hot air balloon floats because the hot air inside is ___ than the surrounding cold air.

Less dense

Explain how ships can float despite being made of dense materials.

Ships float due to design.

• Hollow structure reduces density.

• Displaces water equal to weight.

• Buoyancy principle enables floating.

True or False: Submarines use ballast tanks filled with water to rise to the surface.

False. Submarines fill their ballast tanks with air to increase buoyancy and rise to the surface.

Identify a real-life application of the principles of floatation.

Airships are filled with lighter gases like helium to remain afloat in the air.