1. Mechanics
Intro & Definitions

2. Definitions: Mechanics: Kinematics: Dynamics:
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: Curvilinear: Random
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. Classify the type of motion
Ex:
Classify the type of motion
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
Rect.
Rect.
Curv.
Curv.
Rect.
Rect.
Random
Random

5. Definitions: Trajectory: Vantage Point: Ex. Baseball
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. Ex. Ball on a moving train
From Thrower:
From Outside:

7. Vectors vs Scalar: Scalar: Vector:
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: ∆d = d2 – d1 ∆d = (-4) – (3) ∆d =-7km
Find the displacement for a driver who started at marker +3km and ended at marker -4km. -5 -4 -3 -2 -1 1 2 3 4 5
∆d = d2 – d1
∆d = (-4) – (3)
∆d =-7km

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