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Forces. Why does an object move? Why does an object change directions? Why does an object stop, or start to move?. What is a Force?. 3 Main Types of Forces PUSH ex) friction, drag, normal force PULL ex) gravity ROTATIONAL ex) twist, turn, spin Described by: magnitude (strength)
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Forces • Why does an object move? • Why does an object change directions? • Why does an object stop, or start to move?
What is a Force? 3 Main Types of Forces • PUSH ex) friction, drag, normal force • PULL ex) gravity • ROTATIONAL ex) twist, turn, spin Described by: • magnitude (strength) • direction Units measured in Newtons (N)
Unbalanced Forces change the motion of an object nalanced Forces change the motion of an object
Unbalanced Forces • Causes a change in movement • start moving • stop moving • move faster or slower • change directions
= + 1 direction Force 1 = Net Force greater + Force 2 than zero UNBALANCED FORCE
- - When one force is bigger - Causes objects to move, stop, and change directions. = Overall direction UNBALANCED FORCE Bill Nye Video: http://www.youtube.com/watch?v=K3S6WKJIohw
Summary of unbalanced forces • Can happen when • Forces are in SAME DIRECTION (then strength doesn’t matter) • Forces are in OPPOSITE DIRECTION then there must be DIFFERENT STRENGTH
Unbalanced force • Ex) Walking the dog • Draw an arrow for boy • Draw an arrow for dog • Are arrows the same direction? • Are arrows the same size?
BALANCED Forces mean NO change in the motion of an object nalanced Forces change the motion of an object
example 0 = - 2 forces cancel each other = No net force BALANCED FORCES
SUMMARY of Balanced Force • Can happen when • Forces are in OPPOSITE DIRECTION and SAME STRENGTH • The net force will then be equal to 0. • NO CHANGE IN MOVEMENT
Forces- Balanced or Not? • EXAMPLES: • #1 • #2 • #3 6N+3N=9N
- ? = What about this force?
Newton’s Laws ofMotion Cool!
I like to sing the abc’s! Ouch! What’s with the apple dude?
INTERESTING FACTOID • At a site that sells rare books, there are some very rare first editions of Newton’s books still available for purchase: • Book Description: London, Joseph Streater, 1687 4to. Contemporary full Dutch vellum (according to Babson, "most of this issue was sent to Holland and there bound in Dutch vellum") with four raised bands and "Newton" in ink on spine. Price:US$ 453,288.98 • Book Description:JussuSocietatisRegiae ac TypisJosephiStreater. ProstatapudpluresBibliopolas, London, 1687. FIRST EDITION. Price:US$ 325,000
THE ORIGINALS • It seems that Newton’s original manuscript is now online. Information can be found at this link http://digitaljournal.com/article/315935 • Cambridge University has made his manuscripts available free online and here is the link http://cudl.lib.cam.ac.uk/collections/newton
An object at rest will remain at rest and an object in motion will remain in motion at constant velocity unless acted upon by an unbalanced force.
INERTIA Tendency of objects to resist changes in motion Larger mass = more resistance to change
BIG IDEAS • There are forces that exist in nature that create movement and allow objects to become stationary. • Without forces, we would have mayhem. • Newton’s 1st Law (of inertia) summarizes this