Floating and sinking buoyancy PowerPoint.ppt

Physics year 9

1. FLOATING AND SINKING

2. FLOATING AND SINKING
The objects can be float or sink depends on the density of the objects
and the liquids.
Density is the mass of an object or substance divided by its volume. 

3. If the object is less dense than the liquid, the object will float
If the density of the object is denser than the liquid, the object will
sink

4. Liquid Density
Liquids are made up of tiny
particles. The density of a liquid
depends on how tightly packed
together these particles are. 
Different liquids have different
liquid densities. 
Water has a density of 1.0 g/cm³.
Some liquids have a higher
density than water. These liquids
will sink below the water, leaving
the water to float above. 
Other liquids have a lower
density than water. These liquids
will float above the water. 

5. Predictions
A prediction is a statement about what you think will happen.
Make a prediction about the density of each of these liquids:
•Vegetable oil
•Honey
•Water (with a drop of food colouring) 
•Washing-up liquid  
Which liquid has the highest density? 
Which liquid has the lowest density? 
Order the liquids in what you consider to be highest density to
lowest density.

6. What Next?
Now that you have made a prediction,
complete the experiment. 
Use the Discovering Density Experiment
Instructions to guide you through the
process.
Check to see if your predictions were correct
and log your results. 

7. Upthrust force
If the upthrust force is equal to weight of the object, it will float.

8. Submarine

9. Submarine
•When the submarine is on the surface :the ballast tanks are
filled with air.
•When the submarine dives, water is pumped into the ballast
tanks to replace the air.
•Tanks of compressed air are kept on the submarine and when
the crew wants to go back to the surface, they pump air into
the ballast tanks to force out the water.

10. Identifying gemstones
Gemstones are minerals found in the earth. 
Quartz is the most common mineral in the
earth.

11. Identifying gemstones
1.Their colour
2.Whether white light splits into a spectrum
when it goes through the gem
3.Their hardness
4. Their crystal shape