# Mechanics - PowerPoint PPT Presentation

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Mechanics

## Mechanics

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##### Presentation Transcript

1. Mechanics Intro & Definitions

2. Definitions: • Mechanics: • studies the motion of objects when subjected to forces or displacements • Kinematics: • studies the motion of objects • Dynamics: • studies WHY objects move

3. Motion: • Three different types: • Rectilinear: • motion along a straight line • Ex. sprinter running, sliding cell phone across a table, car traveling down a street • Curvilinear: • Motion along a curved path • Ex. kicked football, car traveling turning a corner • Random • Combo of rectilinear & curvilinear • Ex. skier, hockey player, helicopter

4. Train traveling down a straight track A slider on an air-track The valve of a moving bicycle wheel A ball rolling off a table Arms moving when a person walks A weight oscillating vertically on the end of a spring A fly flying around a room Football players running on a field Ex: Classify the type of motion Rect. Rect. Curv. Curv. Rect. Rect. Random Random

5. Definitions: • Trajectory: • Describes the path of an object in motion • Vantage Point: • Point of view that the path of motion or trajectory is observed from • Path of motion or trajectory can “look different” depending on vantage point • Ex. Baseball Runner appears differently from the point of view of the pitcher, the 1st baseman, the outfielder, the fans…

6. From Thrower: From Outside: • Ex. Ball on a moving train

7. Vectors vs Scalar: • Scalar: • Quantity described with a magnitude & unit • Ex. drove 10 km • Vector: • Quantity described with a magnitude, a unit & a DIRECTION • Ex. drove 10km North

8. Describing & Calculating Motion: • Distance: • Distance traveled • Scalar quantity • d • Displacement: • Difference between the final & initial position • Vector quantity • Describes magnitude & direction of change in position • ∆d • one or two dimensional d = ∆d (ex. 10m) d = 20m BUT ∆d = 10m ∆d = d2 – d1

9. Ex: You are at your locker. You walk 4m east down the hall. You realize you are going the wrong direction, turn around & walk 10m west. 4m 10m What is… • Your displacement? • Your distance traveled? 6 m west 14 m

10. Ex: Find the displacement for a driver who started at marker +3km and ended at marker -4km. ∆d = d2 – d1 ∆d = (-4) – (3) ∆d =-7km

11. Try: pg 166 #1 - 6 pg 170 #1 - 3