Does water shoot farther from a hole near the bottom of a container or near the top? The answer reveals how hydroelectric dams generate power.
Punch four holes at different heights in a milk carton. Fill it with water and remove the tape from all holes at once. The lowest stream shoots the farthest because more water weight presses down on it.
This is the same principle behind hydroelectric plants. Dams funnel high-pressure water from the bottom of a reservoir through a turbine to generate electricity.
Hypothesis
The hypothesis is that water pressure can be used to generate electricity.
The deeper the water, the more weight sits above — and the stronger the push against anything at that depth. Punch four holes at different heights in a milk carton, tape them shut, fill it with water, and remove the tape from all holes at once. The lowest stream shoots the farthest because more water weight presses down on it. The streams higher up travel a shorter distance, where less weight sits above the hole. That same principle drives hydroelectric dams, which funnel high-pressure water from the bottom of a reservoir through a turbine to generate electricity.
Hydroelectric power uses moving water to spin a wheel and create electricity. Water at the bottom of a container has more weight pressing down on it, so it shoots out with greater force. Dams use this same principle, funneling high-pressure water from the bottom of a reservoir through a turbine to generate electricity.
Method & Materials
You will cut the top off a milk carton, punch holes in the side, and tape them up. Then, you will fill the carton with water and remove the tape to observe the water pressure.
You will need a half gallon paper milk carton, a gallon of water, an awl or 10p nail, masking tape, a ruler, a magic marker, a pair of scissors, and a pad of paper and pencil to make notes.
MEL Physics — hands-on physics experiment kits delivered monthly — real experiments, not just reading. (Affiliate link)
The results showed that the water from the bottom of the milk carton went the furthest. This demonstrates the power of water pressure and how it can be used to generate electricity.
Why do this project?
This science project is interesting and unique because it shows how water pressure can be used to generate electricity, which is a common source of energy used in many places.
Also Consider
Experiment variations to consider include using different sizes of holes in the milk carton and using a water bottle instead of a milk carton (see videos).
Full project details
Additional information and source material for this project are available below.
These videos explain the science behind this project and demonstrate key concepts used in the experiment.
Want to witness the power of water under high pressure? Watch as this teacher uses a lit BBQ skewer to create holes in a water bottle and see for yourself how the water flows out of the bottom holes at a faster velocity, demonstrating the incredible force that can be generated by water.
Check out this awesome experiment where a student uses a penknife to cut holes in a water bottle and observes how the water flows out at different speeds depending on the position of the hole! It's this power of water that makes hydroelectric power a possibility!
