Motion - 1 - Intro Vectors Scalars | High School

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High School
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High School Physics
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2024
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1 Unit 1: Mechanics Intro & Definitions (Quantum Ch. 7, 8 & 9.1) Definitions:  Mechanics: ◼  Kinematics: ◼  studies the motion of objects when subjected to forces or displacements studies the motion of objects Dynamics: ◼ studies WHY objects move 1.1 Motion: Three different types: ◼ Rectilinear:  motion along a straight line  Ex. sliding cell phone across a table ◼ Curvilinear:  Motion along a curved path  Ex. car traveling turning a corner ◼ Random  Combo of rectilinear & curvilinear  Ex. Hockey player, helicopter Ex: Classify the type of motion Train traveling down a straight track Rect. A sprinter running down 100m track The valve of a rotating bicycle wheel Curv. A pushed ball falling off a table A weight oscillating vertically on the end of a spring Rect. Random F. A fly flying around a room G. Football players running on a field A. Rect. B. C. Random. D. E. Random Definitions:  Trajectory: ◼  Describes the path of an object in motion Vantage Point or f.o.r. ◼ ◼ 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. Ball on a moving train From Thrower: From Outside: 1.2 Vector vs Scalar  Scalar: ◼ ◼ ◼  Quantity described with a number (magnitude) & unit Ex. time, mass, volume, distance Ex. drove 10 km Vector: ◼ ◼ ◼ Quantity described with a magnitude, a unit & a DIRECTION Ex. Displacement, velocity, acceleration, force Ex. drove 10km North 1.2 Vector vs Scalar  When considering direction: ◼ ◼ ◼ Use cardinal directions if possible (East, west, north, south) Positive or negative matters (E & N are +, S & W are -) Coordinate system (x, y) defines plane 1.3 Distance vs Displacement d = ∆d  Distance: ◼ ◼ ◼  Distance traveled Scalar quantity d Displacement: ◼ ◼ ◼ ◼ ◼ (ex. 10m) d = 20m BUT ∆d = 10m Difference between the final & initial position Vector quantity Describes magnitude & direction of change in position ∆d = xf – xi ∆d Different motions can result in identical displacements Ex: You are at your locker. You walk 4.0m east down the hall. You realize you are going the wrong direction, turn around & 4.0m walk 10.0m west. 10.0m What is… 6.0 m [W] a) Your displacement? b) Your distance traveled? 14.0 m Ex: Find the displacement for a driver who started at marker +3km and ended at marker -4km. -5 -4 -3 -2 -1 0 1 2 3 4 5 ∆d = xf – xi ∆d = (-4) – (3) ∆d =-7km HW: pg 189 #1 pg 207 #2, 4, 5