20048 AC Science Year 6 Physical sciences

Making the most of water power
Hydro-electric power plants are built at the base of dams where the
water is forced onto the blades of turbines.
In this investigation, you will discover why they are not built at the top
of a dam.
You will need:
• I empty I -litre milk/juice carton • I large nail
• masking tape
What to do:
0 Use a nail to make holes in the carton at
2-cm intervals, as shown in the diagram.
All holes must be the same size.
f) Tape over all holes with one length of
masking tape.
8 Draw a line at the top of the carton. Fill the
carton with water to this level.
0 Hold the carton firmly at the edge of a
kitchen sink and rip away the strip of tape. e
Results:
I. Untaping all holes at once
How does the water empty through
each hole and how does this change
as the water level falls?
2. Untaping one hole at a time
Hole
I. @2 cm
2. @ 4 cm
3. @ 6cm
5-----t,,i:
4 __ --4,..::::::::.i..::-"--'----
3 __ .....1,..,..::.,-.._
2-----t,,,::::--{I
1
................ r-
C, Observe and record how the
water empties through each hole and
how it changes as the water level falls.
C, Tape all the holes individually.
0
Observation
Refill the carton. Untape one hole and
measure the distance between the edge
of the sink and where the water lands.
Re-tape the hole.
Repeat Step 7 for the remaining holes.
Distance (cm)
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Conclusion:
3. Explain, using evidence, why hydro-electric power plants are built at the base of dams.
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AUSTRALIAN
CURRICULUM SCIENCE (Year 6)