Presentation on theme: "SEISMIC SLEUTHS Part 1 Newton’s Laws EARTHQUAKES AND PHYSICS? Newton’s laws Liquefaction lab Smart Sitting Energy and Quakes CAN BUILDINGS BE MADE SAFER?"— Presentation transcript:
SEISMIC SLEUTHS Part 1 Newton’s Laws EARTHQUAKES AND PHYSICS? Newton’s laws Liquefaction lab Smart Sitting Energy and Quakes CAN BUILDINGS BE MADE SAFER? Building Fun Structural Reinforcement BOSS Earthquake in a Box Building Challenge Find and Fix the Hazards Strengthening your House
Newton’s Laws of Motion: 1st Law: Law of Inertia Objects keep on doing what they are doing. http://www.physicsclassroom.com/mmedia/newtlaws/cci.cfm
Mass is directly related to inertia. The greater the mass the greater the tendency to resist change of an object’s motion. objects will continue to do as they are doing with out friction.
Equilibrium: if the net force on an object is zero (at rest or moving at a constant velocity)
Static friction Static friction results when the surfaces of two objects are at rest relative to one another
2 nd law: Net force: something that disturbs an object’s equilibrium (net force changes an object’s velocity or acceleration) Need to be able to find the net force (sum of all forces on an object) since net force causes an object’s acceleration http://www.physicsclassroom.com/mmedia/kinema/avd.cfm
2nd Law: acceleration of an object is proportional to the mass of the object being accelerated F=ma – a is in m/s/s – m is in kg, – F is kgxm/s/s or Newtons F = mg (weight) –Gravity (9.8 m/s/s) http://www.physicsclassroom.com/mmedia/newtlaws/efar.cfm
Unbalanced force The normal force is cancelled by the force of gravity. The book is sliding to the right but there is no force in that direction. Because SLIDING friction is currently the only horizontal force it will cause the book to come to a stop
Sliding Friction If a car slams on its brakes and skids to a stop (without antilock brakes), there is a sliding friction force exerted upon the car tires by the roadway surface.
Causes of friction: When the high points of each surface touch they bond, you must break these bonds to move one of the pieces (origin of static friction) As surfaces move across each other, electrostatic forces continue to attract between high points, resulting in the weaker kinetic friction Air drag (any fluid) depends on speed of the motion (getting larger as speed increases) size and shape of object density of fluid
Forces (Ff) Friction Force: The contact force that acts to oppose sliding motion between surfaces. Parallel to the surface Opposite the direction of sliding Normal force (FN): The contact force exerted by a surface on an object. Perpendicular to and away from the acceleration of the object barring any resistive forces.
3 rd law: For every action there is an equal and opposite reaction http://www.physicsclassroom.com/mmedia/momentum/crete.cfm