PHYS16 – Lecture 4 Physics of 1D Motion September 15, 2010

Administration Key Concepts – Physics 1D motion Displacement, Velocity, & Acceleration Agenda

Clickers, Textbook, Connect Math Exam – Look at messages – Due Sunday Homework Assignments – Lab homework due today – Written homework due Friday 2.38 – displacement not distance Labs – Partners… Administration

Key Concepts: Physics 1D Motion Displacement, Velocity, & Acceleration – Know the definitions of these terms – Know how they are related Motion with Constant Acceleration – Solve for constant accel. get Kinematic Eqs. – Use the Kinematic Eqs. to solve problems Race Car Free Fall

Define Terms

Displacement Displacement vs. Distance – Displacement = final position – initial position with both magnitude and direction – Distance = total position traversed from final position to initial position, just magnitude

Velocity Velocity vs. Speed – Velocity – final position minus initial position divided by time, both magnitude and direction – Speed – how fast you are going, just magnitude 60 mph

Acceleration – Final velocity minus initial velocity divided by time, both a magnitude and a direction – How much an object speeds up or slows down com Position graph where acceleration is not 0

Questions: A=Yes, B=No Can displacement be zero and distance be positive?(Yes) Can distance ever be negative?(No) Can speed ever be negative?(No) Can acceleration be negative?(Yes) Can an object that is stopped at t=0 have an acceleration?(Yes) If an object is traveling at a constant velocity can it have an acceleration?(No)

Observe and Report – Use a Graph

Demo: Remote Control Car

Demo: Remote Control Car Draw the position vs. time, velocity vs. time, and acceleration vs. time graph for each situation – Constant velocity – Constant velocity forward then constant velocity backward – Constant acceleration

Use Math

Demo: Determine x, v, & a mathematically! XVAXVA

Determine v x=3t 2 +4t -5 – v=6t+4 a=4t 2 +3t+5 – v=(4/3)t 3 +(3/2)t 2 +5t+v 0 – laksdj

Summary Displacement vs. Distance Velocity vs. Speed Acceleration Know how to interconvert between them!

For Next Time… Online lab homework due Wednesday Written homework due Friday Online Math Exam due Sunday Lab this week! Pick 3 partners!