Center of Gravity
Challenge: Leg Lift
Stable vs. Unstable
Stable Structures The forces of gravity acts on all parts of the structure All parts are evenly distributed around the center of gravity = the structure is stable
Unstable Structures A structure may collapse if the external forces causes the structure to become unbalanced Also known as an “unbalanced” structure
Firm Foundation The foundation must be stable. If not, compressive forces may cause structure to tip and become unstable. Soil type and formations critically important in building planning
Build on FIRM FOUNDATION!!! Leaning Tower of Pisa Build on FIRM FOUNDATION!!!
Class Challenge: Super Glue Chair
Center of Gravity
What is center of gravity? The center of gravity is the specific point where all of the mass of the structure is evenly distributed around
Mass vs. Weight Mass Amount of matter in an object Weight Force of gravity felt on that object
What is “equilibrium” A state in which opposing forces or influences are balanced in a “system” A state of physical balance
What is a “system” A structure made up of parts all related to one another
Challenge: The Impossible Leap
Ways to Increase Stability Lower the center of gravity = widening structure Increase speed (bike)
Ruler Experiment
Experiment: Spoon & Fork Steps Hand in your graphic organizer. In partners of 2, get a spoon, fork, toothpick and a beaker Put fork and spoon together Add toothpick Find center of gravity by balancing on table *Bonus* - break off toothpick where center of gravity is Draw your “system” and label. Include center of gravity, equilibrium line. Explain why the “system” is balanced (ie: why is it balancing?)