Mrs. Nowlan's Grade 7 Science
Unit 4: Structures and Forces
Concepts:
- investigate factors affecting stability of a structure and techniques used to increase stability.
- learn that lowering a structure's centre of gravity and distributing a structure's mass over a large area both result in higher levels of stability.
Which type is which?
Dates to Remember
January 10: Discussion and note taking from pages 321 - 343
January18: Review day
Final Project: Due January 28
Mid Term Science Exam: January 22
Definitions
Stable structure: one that is not likely to tip or fail.
Centre of Gravity: the point at which all of the gravitational force of an object may be considered to act. Movement away from the centre of gravity causes a structure to fall.
Pilings - large, metal, concrete or wood cylinders that are pushed deep into loose soil until they rest on bedrock. They are used to add support to structures that are built on soft foundations.
Footings: concrete foundations beneath walls that are wider than the walls themselves. Footings spread the load of the structure, reducing the stress.
Arch
(B)
Beam or Truss (A)
Cable-stayed
Suspension
(C)
Cantilever (D)