Bobsleigh
device · 1880 · Electric age
A steerable sled.
What it is made of
- Steering wheel — has part. A steering wheel.
Principles and materials it uses
- Steel — is made of. A bob has steel runners and frame.
- Friction — uses. Speed is kept up by the low friction of ice.
History: what it evolved from and what it influenced
- Sledge — evolved from. A sled.