FLUIDS: Grade 8
SPECIFIC LEARNING OUTCOMES
- STSE 109.02, 111.01
- Knowledge 307.08, 307.09, 307.10, 309.01, 309.02
- Initiating and Planning 208.02
- Analyzing & Interpreting 210.07
- Communication and Teamwork 211.03
| Archimedes’ Principle:
A body will float in a fluid if the weight of the object is equal to the weight of the fluid displaced by the object (called the buoyant force) Corollary: If an object is unable to displace a weight of fluid equal to its own weight…THE OBJECT WILL SINK |
mass must be converted to weight (newtons) in order to apply Archimede’s Principle. | As shown (far left), the weight of the ship acts downward, whereas the buoyant force (far left) provided by the displaced fluid, acts upward. As shown, the buoyant force is equal to the weight of the water displaced by the ship (below the water-line). When the ship is placed in the ocean it will continue to sink until the buoyant force of the water on the ship and the weight of the ship exactly balance. |
The weight of any fluid displaced is sensitive to the density of the fluid. Consider the four cases shown below; in each case shown the supertanker has exactly the same weight.
CONTEST: Divide your class into groups of three students. Each group must write a detailed scientific explanation (using their understanding of Archimedes’ Principle and their knowledge of density), to account for the
observations shown in the sketch below. One member of each group will present their explanation to the rest of the class. The group with the clearest explanation (as judged by the rest of the class) will de declared the winner. Prizes optional!
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