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Kinematics in One-Dimension. Kinematics in One-Dimension. Sections Covered – Honors Physics Chapter 3: pages 42 – 60 Chapter 5: pages 80 – 107 Topics Covered Position and time Average speed and average velocity Instantaneous velocity Average acceleration
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Kinematics in One-Dimension • Sections Covered – Honors Physics • Chapter 3: pages 42 – 60 • Chapter 5: pages 80 – 107 • Topics Covered • Position and time • Average speed and average velocity • Instantaneous velocity • Average acceleration • Kinematic formulas and problem solving • Graphical analysis • Free fall and acceleration of gravity
A Study in the Classics • *Classical Mechanics – the study of the motion of objects (force, energy, rotation, momentum…etc) • *Kinematics – Description of how objects move. • *Dynamics – Study of forces and their affects.
Time • Time (t) • SI Units: Seconds (s) • SI Units: Metric *International System of Units • Instantaneous Time – A specific or instant time.
Intervals • Time Intervals – a time of duration, how long? Variable: Δt • Delta (Δ) – Greek letter, means ‘change in’. • Δ = final value – initial value
Scalar vs. Vector • Scalar - Quantity described by magnitude only • Vector – Quantity described by magnitude AND direction *What is Magnitude?! Magnitude = Numerical Amount
Position • Position - where an object is at a particular moment Variables = x, y, z • Change in Position: Δx, Δy, or Δz SI Units: Meters (m)
Displacement • Displacement –the shortest straight-line distance between the two points regardless of the path. • VECTOR quantity Change in Position: Δx = B - A Δx = xf - xo B *Note: Many times the subscript o is used for initial quantities A
Distance • Distance - Total path between two points with the route traveled taken into account. • SCALAR value SI Units: Meters (m) *Can Distance Be Negative? No, it’s considered an absolute value B A
Positive and Negative Positive = Large Negative = Small • Positive and negative signs are indications of direction, NOT magnitude. WRONG!
Average Speed Average Speed = *Distance is a quantity scalar *Speed is a quantity scalar SI Units: meters (m) m = = s seconds (s)
Average Velocity Average Velocity = *Displacement is a quantity vector meters (m) m *Velocity is a quantity vector = = s seconds (s) SI Units:
*Velocity vs. Speed Road Trip!! Car A decides to go to Memphis for some blues and BBQ (approx. 725 miles) Car B decides to go to Chicago for some pizza and a Cubs game (approx. 725 miles) Both cars arrive at their destination at the same time. Did the cars have the same velocity? Did the cars have the same speed?
Example 1 The position of a runner is plotted as a function of time, moving along the x-axis. He moves from an initial position xo = 50.0 m to a position xf = 30.5 m in a time of 3.00 s. What is his average velocity?
Example 2 A person jogs eight complete laps around a quarter mile track in a total of 12.5 minutes. Calculate: • The average speed • The average velocity
Example 3 Acar goes down a certain road at an average speed of 40 km/h and returns along the same road at an average speed of 60 km/h. Calculate the average speed in km/h for the round trip.
Average Acceleration • Average Acceleration = Change in velocity over the change in time. Variable: • Average Acceleration is a vector quantity SI Units: m/s = = s
Positive and Negative Accelerations • A positive acceleration ≠ (necessarily) getting faster • A negative acceleration ≠ (necessarily) slowing down. • Positive acceleration simply means accelerating in a positive direction • Negative acceleration simply means accelerating in a negative direction.