Mrs. Nowlan's Grade 7 Science

Unit 4: Structures and Forces

Topic 6: Designing with forces

Concepts:

• interpret variations in structural design and evaluate their effectiveness
• identify forces within a structure

Definitions

Arch: rounded structures that are supported by the keystone (wedge) that presses against the two sides of the arch.

Brace: a solid beam that supports rectangular structures

Cantilever: a horizontal board or span that is supported by a very strong column at one end. Double cantilever bridges are very strong structures that support heavy vehicles (page 322).

Beam: a metal structure that forms a column. To save on metal and to make them less heavy, beams com in cylindrical, I-beam, L-beam, T-beam and box beam shapes.

Corrugations: wave like shapes of material add strength to a structure, e.g. wavy paper inside cardboard.

Flying Buttress - an external column that helps to support large buildings e.g. Notre Dame Cathedral in Paris. Large tree roots perform the same function.

Sites

Cantilever bridge