Name: 7.ダム (7. Dams)
Uploaded: 2021-01-14T11:05:28.000Z
Duration: 3 min 47 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

程度の副詞

For thousands of years, and in nearly every civilization,

As the first video in this series showed,

water exerts pressure on any surface that it contacts,

and the magnitude of that pressure is proportional to the depth, h.

For a dam to do its job, it must resist the forces generated by these pressures.

Common strategies for doing so include buttress dams,

and to control water elevation in rivers,

with straight, horizontal members between them.

these horizontal members is carried by bending,

We can build a dam that works in this way

so that they can support it, like the piers of a real dam.

For simplicity, we use marbles to represent the water.

Which part of the dam do you think will collapse first?

As the depth of the model water increases,

the cardstock bends, until the dam collapses,

The marble depth that produced failure is 4 centimeters,

and as you can see, failure started at the bottom.

is to use an arch laid on its side, like this.

If you watched our "Arches and Chains" video,

you will know that arches can be very effective in load carrying

we make the cardstock panel a little longer

it automatically curves into an arch shape.

As we pour in the marbles, raising the model water level,

the cardstock resists the resulting pressure

Even so, the arch dam also eventually collapses

As before, failure begins at the bottom of the dam

That is why arch dams  are so often used  for big, tall dams.

As a side note, you might be interested to know

is usually made thicker toward the bottom

To learn more about how soil and water interact

we hope you will view more of the videos in this series.

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