Please turn in your week 6 accountability sheet and pick up week 7. If you did not bring your...

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• Please turn in your week 6 accountability sheet and pick up week 7. • If you did not bring your workbook, share with a table partner.

Transcript of Please turn in your week 6 accountability sheet and pick up week 7. If you did not bring your...

Page 1: Please turn in your week 6 accountability sheet and pick up week 7. If you did not bring your workbook, share with a table partner.

• Please turn in your week 6 accountability sheet and pick up week 7.

• If you did not bring your workbook, share with a table partner.

Page 2: Please turn in your week 6 accountability sheet and pick up week 7. If you did not bring your workbook, share with a table partner.
Page 3: Please turn in your week 6 accountability sheet and pick up week 7. If you did not bring your workbook, share with a table partner.

REVIEW: Newton’s first law

• Sometimes referred to as the law of inertia

• “An object at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.”

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Balanced and Unbalanced Forces• What’s that mean?

• This is equilibrium!equal magnitude, opposite direction

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• Now consider a book being pushed to your right…

• Unbalanced forces cause Accelerations

These pics are called Free Body Diagrams

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Drawing Free-Body Diagrams

• “diagrams used to show the relative magnitude and direction of all forces acting upon an object in a given situation”

• Use vector arrows

• Example:

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Our first free body diagram

• A book is at rest on a tabletop

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• A gymnast is suspended motionless from the ceiling by two ropes. Diagram the forces acting on the gymnast.

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• An egg is free-falling from a nest in a tree. Neglect air resistance. Diagram the forces acting on the egg as it is falling

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• A flying squirrel is gliding (no wing flaps) from a tree to the ground at constant velocity. Consider air resistance. Diagram the forces acting on the squirrel

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• A rightward force is applied to a book in order to move it across a desk with a rightward acceleration. Consider frictional forces. Neglect air resistance. Diagram the forces acting on the book.

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• A rightward force is applied to a book in order to move it across a desk at constant velocity. Consider frictional forces. Neglect air resistance. Diagram the forces acting on the book.

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• A college student rests a backpack upon his shoulder. The pack is suspended motionless by one strap from one shoulder. Diagram the vertical forces acting on the backpack.

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• A skydiver is descending with a constant velocity. Consider air resistance. Diagram the forces acting upon the skydiver.

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• A force is applied to the right to drag a sled across loosely packed snow with a rightward acceleration. Diagram the forces acting upon the sled.

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• A car is coasting to the right and slowing down. Diagram the forces acting upon the car.

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Determining the Net Force

• A. B. C.

• net force is the vector sum of all the forces that act upon an object (“Where is the imbalance?”)

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• Figuring out the net force: Ask yourself these questions: In what direction and of what magnitude is the imbalance?

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Determine the net force acting upon the object

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The net force is known for each situation. However, the magnitudes of a few of the individual forces are not known. Analyze each situation individually

and determine the magnitude of the unknown forces.

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