Buoyancy
What do we call the upward force that pushes things up in water?
What is buoyant force?
Density is how much ______ something has in a certain amount of space.
What is mass?
When you put an object in water, the water that moves out of the way is called what?
What is displacement?
This is the first step in the scientific method, when you notice something and start to wonder about it.
Asking a question (or making an observation)?
The upward force that a fluid (like water) pushes on an object placed in it. This force is why some things float.
Buoyancy
If something floats, is it lighter or heavier than the water it pushes aside?
Lighter
What do we use to measure how much space something takes up?
What is volume?
A floating object displaces water equal to its ___.
What is weight?
A testable statement or prediction that scientists make before experimenting.
What is a hypothesis?
When an object is placed in water, it pushes water out of the way. The amount of water pushed aside equals the object’s volume (if fully submerged) or the weight of the object (if floating).
Water Displacement
Who shouted “Eureka!” after discovering how objects float in water?
Archimedes
Why does a rock sink in water but a cork floats?
Because the rock is denser than water, and the cork is less dense.
True or False: A floating object always displaces an amount of water equal to its volume.
False? (It displaces water equal to its weight, not its full volume unless it sinks.)
The part of an experiment that you change on purpose to test its effect.
What is the independent variable?
A testable idea or prediction about what you think will happen in an experiment. Example: “If I drop a rock in water, then it will sink because it is denser than water.”
Hypothesis
Why can a big heavy ship float, but a small rock sinks?
The ship spreads out its weight and displaces more water.
True or false: Density is how much weight in a space.
True
A boat floats because the large amount of space inside makes it displace a big ___ of water.
What is volume?
After running an experiment, scientists do this to the data to see if their hypothesis was correct.
What is analyze the results?
The one thing you change in an experiment to test how it affects the results.
Independent Variable
What is more buoyant, a bowling ball or a basketball?
Bowling ball
True or False – A bigger object is always denser than a smaller one.
False
An ice cube floats with about 90% under the water and 10% above. The water displaced equals the cube’s ___.
weight
The final step of the scientific method, when you explain what you learned and share it with others.
The final step of the scientific method, when you explain what you learned and share it with others.
Who came up with the famous principle about buoyancy.
Archimedes