How do ships float even though they are so heavy?
• What is buoyancy?
– Buoyancy is the upward force caused by a fluid such as water.
• What is Archimedes Principle?
– The buoyant force is equal to the weight of the displaced water.
• What is density?
– Density is the mass of a material per unit volume. – Example: The density of steel is 10 times more than the density of wood.
I think when the weight of the object is greater than the displaced water, it will sink. If the weight of the object is equal to the weight of the displaced water, it will float.
Archimedes Principle and Buoyancy
• • • • • • • 1 big container. 1 medium-sized container. 1 small container. A weighing scale. Metal blocks Water A note pad for writing down the results.
• Weigh the large container on the weighing scale. • Fill up the medium size container with water till the brim. Place it in the large container. • Place the object whose displacement is to be measured in the medium-size container. Observe the water being displaced into the large container. Does the object float or sink? • Remove the medium-size container. Weigh the large container with the displaced water. Subtract the weight of the large container. This is the weight of the displaced water. • Weigh the object. • Compare the weight of the object and the weight of the displaced water.
Object Weight of object (oz) Weight of displaced water (oz) Floats or Sinks? Small container 2 2 Floats Metal blocks 3.5 0.5 Sinks Small container with metal blocks 5.5 5.5 Floats
The hypothesis was proved to be true. When the weight of the object was greater than the displaced water, it sank. When the weight of the object was equal to the weight of the displaced water, it floated.