# Friday PS Forces Part 2. Fundamental ideas Balanced forces on an object will NOT cause the object to change its motion Change of motion is caused by an.

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Friday PS Forces Part 2

Fundamental ideas Balanced forces on an object will NOT cause the object to change its motion Change of motion is caused by an imbalance of forces in opposite directions Forces come in many types, including contact, gravitational, and frictional forces

Friction Under-acknowledged about how important it is to the normalcy of your life

In-class assignment Imagine you in a happy place doing something that involves you moving Please keep it “G” or “PG” rated What would change if there was no friction? –Think of your actions –Think of your surrounding environment –Think of your personal being

Assignment List at least 3 things/actions that would result from no friction. They could be new actions/circumstances They could be alterations of old actions/circumstances Write your response in a paragraph or two. –Use full sentences. –Introduction and closing sentences ARE REQUIRED

Friction Force applied opposite to the direction of motion Amount of force depends on: –The roughness of the surfaces being put together –The force used to push surfaces together Friction force Applied force

How does friction effect your live? Harmful friction –Friction between moving parts Helpful friction –Grip of tires on road Friction involved with your mousetrap

Relationship between motion and Forces Newton clearly stated the relationship in his 3 laws of motion I expect you to be able to recite and understand these laws completely

Rolling Ball

Newton’s first law An object at rest stays at rest or an object in motion stays in motion UNLESS acted upon by a net outside force

Newton

Mass The amount of material located in an object The amount of stuff that makes up an object

Inertia The resistance of an object to change of motion The more massive an object, the more inertia it possesses

Newton’s 2 nd law If there is a net force on an object, then the object will accelerate The amount of acceleration depends on the following relationship: A = F net m

An object will gain more acceleration as more force is applied An object will gain less acceleration if more mass is added to it

Homework Read 331-332, 346-351 Practice questions 1-3 on p351

Cars If you like it and its in good shape, either: –Keep it and take it home –With my permission, leave it on window ledges If you don’t want it and it is not to be kept, DISSASSEMBLE It! Throw eye-screws, clean axles, wheels, spools into the box

Grades Review to see if you are missing anything!

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