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Exam 1: Chapters 1-4 60% Problems – one problem from WebAssign with different numbers

Exam 1: Chapters 1-4 60% Problems – one problem from WebAssign with different numbers Understand homework problems Review notes and text Try new problems 40% Multiple Choice Questions Review Power Points (on web page) Review Before Class Assignments Try Questions

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Exam 1: Chapters 1-4 60% Problems – one problem from WebAssign with different numbers

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  1. Exam 1: Chapters 1-4 • 60% Problems – one problem from WebAssign with different numbers • Understand homework problems • Review notes and text • Try new problems • 40% Multiple Choice Questions • Review Power Points (on web page) • Review Before Class Assignments • Try Questions • Graphs, Pictures and Drawings (Sketches) • Don’t rely on memorized equations

  2. Chapter 5 The Laws of Motion 5-1a Force – a push or pull. • CT1: The force of the elevator on Norbert and Zot is • up. • down.

  3. Assume the elevator is near the Earth’s surface and that it is right-side up in the cartoon. • CT2: The force of the non-sticky elevator surface on Norbert and Zot is • up. • down.

  4. Assume the elevator is near the Earth’s surface and that it is right-side up in the cartoon. • CT3: The acceleration of Norbert and Zot is • up. • down. • zero

  5. Fig. 5.1, p.113

  6. 5-1 B. Mass The mass of an object is the amount of matter (stuff) in that object. It is the same for a given object everywhere in the Universe. Mass is also called inertia because it resists being moved.

  7. 5-2 Newton’s First Law: A body remains in uniform motion (or at rest) unless acted upon by a net external force. • acceleration due to Earth’s rotation  0.03 m/s2 • acceleration due to Earth’s orbit  0.006 m/s2 • acceleration due to Sun’s orbit  2 x 10-10 m/s2 An inertia frame of reference is a coordinate system (or frame) in which Newton’s Law’s hold. We will assume that the Earth’s surface is an inertial frame and not make errors greater than 0.03/10 = 0.3%.

  8. A. B. C. D. E. CT4

  9. A. B. C. D. E. CT5

  10. 5-3 Newton’s Second Law: The net external force is equal to the mass times the acceleration. F = ma Force and acceleration are vectors • Fx = max • Fy = may remember Galileo! • Fz = maz Normally we will do problems in a plane with only x and y components.

  11. Calibrating a “Force Meter” Experiments show forces add as vectors.

  12. Acceleration is Proportional to Force

  13. Acceleration is Inversely Proportional to Mass

  14. Applications of Newton’s Laws - Method • Draw picture of the problem. • Choose body (bodies) to isolate. • Draw Free Body Diagrams (FBDs) for isolated bodies. • Choose and label coordinate axes. • Apply Newton’s 2nd Law: Fx = max and Fy = may • Solve for F, m or a. • Work out kinematics. • Check solution is reasonable. P5.6 (p.136)

  15. Concept Question 6 • P5.6b: If the parachutist comes to rest over a shorter distance, the force exerted by the ground will be • greater. • less. • the same.

  16. FAB A B FBA 5-4 Newton’s Third Law: If body A acts on body B, then body B acts back on body A with a force equal in magnitude but opposite in direction. FAB and FBA are 3rd Law pairs.

  17. CT7 A. B. C. D. E.

  18. P5.18 (p.137) • Concept Question 8 • P5.18b: If the 5 N force is applied to the heavy box instead, the contact force between the boxes will be • greater. • less. • the same.

  19. 5-5 The Vector Nature of Forces Two Astronauts Pushing a Satellite with Forces that Differ in Magnitude and Direction

  20. P5.22 (p.137)

  21. P5.28 (p.138)

  22. Orbit of Moon about the Sun Actual Exaggerated and incorrect

  23. y x 5-6 Gravitational Force or Weight Fg = mg (weight) g = -9.81 j (m/s2 ) Apparent Weight is the force you actually feel pushing on you – often the floor.

  24. P5.35 (p.138)

  25. Concept Question 9 • P5.35b: If the constant speed of descent is greater than 1.1 m/s, the force of air resistance is • greater. • less. • the same.

  26. Concept Question 10 • P5.33a: Your normal weight is 610 N and the scale in the elevator reads 720 N. The acceleration of the elevator • upward. • downward. • zero.

  27. Concept Question 11 • P5.33c: Your normal weight is 610 N and the scale in the elevator reads 720 N. The magnitude of the velocity of the elevator is • increasing. • decreasing. • zero. • impossible to determine without more information.

  28. 5-7 Normal ForcesThe Normal Force May Equal the Weight

  29. The Normal Force May Differ from the Weight

  30. An Object on an Inclined Surface P5.42 (p.138)

  31. Concept Question 12 • P5.42b: If the angle of the incline is decreased, the normal force will • increase. • decrease. • stay the same.

  32. A. B. CT13

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