02_motion_KSCV5.pptx

Chapter 2 part 1 Review of Motion Along a Straight LineGoals for Chapter 2 part 1A review of the following topicsDescription of straight-line motion in terms of velocity and accelerationaverage and instantaneous velocity and average and instantaneous acceleration Interpretation of graphs of position versus time, velocity versus time, and acceleration versus time for straight-line motionWhat is motion?Change of the basket ball position as a function of timeChange of missile position with timeIntroductionKinematics or Mechanics is the study of motion (position as a function of time). In 1 dimension, x coordinate as a function of time. In 3 dimension, position vector as a function of time. The objective is to find the position as a function of timeVelocity and acceleration are important physical quantities for description of motion. If you know the velocity and acceleration, then you can find the position (coordinate) as function of time. So we need to understand the concepts and the use of velocity and acceleration.Displacement, time, and average velocity—Figure 2.1A particle moving along the x-axis has a coordinate x. x is a function of time t. So it is in motion.The change in the particle’s coordinate is Δx = x2 - x1. in time Δt. Δx is the displacement.The average x-velocity of the particle is vav-x = Δx/Δt. Displacement divided by time. It is the average rate of change of displacement.If you know average velocity vav-x you can find displacement Δx= vav-x Δt and so the position (motion).A position-time graph (an x-t graph) shows the particle’s position x as a function of time t.Instantaneous velocityThe instantaneous velocity is the velocity at a specific instant of time or specific point along the path and is given by vx = dx/dt. (differentiation of x with respect to t)It is obtained from the average velocity by making the time interval smaller and smaller. When the interval is very very small, it becomes the velocity of that moment of time t.Uniform velocity,