Gigo 1249R, Manual, Page: 66 / 80

65
B
rainstorming
B
rainstorming
A dog door is a typical example of an application
which uses both a lever and gravity. It is a small
portal, where a hinge attaches with a flexible flap.
When a dog door is installed on a door, the flexible
flap is closed by its own gravity. When a dog wants to enter
or exist the house, he doesn’t need to wait for his owner to open
the door for him. He can use his head to push the flap. With this
motion, the hinge on the top of the flap becomes the pivot point, activating the
lever motion needed to lift up the flap. Therefore, the dog can go enter and exit
through it. After the dog passes through, the flap closes from its own gravity.
With the application of levers, and the gravity of the dog door, this flap can be
both opened and closed.
Give an example of something in daily life that uses
the same principles as a “dog door”.
Daily
Application
Daily
Application
In the past, in order to prevent an external invasion, people dug deep channels
around castles, and then guided water into the channel. This channel became
a moat. In order to make it convenient to travel in and out of the castle, a
suspension bridge would be built outside of the gate. The bridge itself also
serves as a preventive measure. Its pivot is built on the border of the gate and
the bridge.
To travel in and out of the gate, one only needs to lower the bridge down on the
moat by using its gravity. It then became a passageway, allowing people to enter
and exit the castle. If there were enemies coming, the bridge could be pulled
up by string with a lever to move the bridge
against its own gravity. The bridge would be
pulled up and the gate would be closed.
The bridge at the gate applies both a lever
action and its own gravity to open and close.
Kids, can you simulate the design of the city
walls?
17
Going Through
the Wall
Scientific
Application
Lever and Gravity