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Chapter 4:Kinematics in Two Dimensions. 1.Two-Dimension Kinematics 2.Projectile Motion 3.Relative Motion 4.Uniform Circular Motion 5.Velocity and Acceleration in Uniform Circular Motion 6.Nonuniform Circular Motion.
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Chapter 4:Kinematics in Two Dimensions 1.Two-Dimension Kinematics 2.Projectile Motion 3.Relative Motion 4.Uniform Circular Motion 5.Velocity and Acceleration in Uniform Circular Motion 6.Nonuniform Circular Motion
Stop to think 4.1 P 93Stop to think 4.2 P 97Stop to think 4.3 P 102Stop to think 4.4 P 107Stop to think 4.5 P 110Stop to think 4.6 P 113 • Example 4.3 P97 • Example 4.4 P98 • Example 4.5 P100 • Example 4.6 P101 • Example 4.9 P106 • Example 4.13 P110 • Example 4.15 P114
Instantaneous velocity The Instantaneous velocity vector is tangent to the trajectory. The direction of the velocity is to the curve.
The instantaneous acceleration can bedecomposed into parallel and perpendicular components
Stop to think:This acceleration will cause the particle to: • Speed up and curve upward • Speed up and curve downward • Slow down and curve upward • Slow down and curve downward • Move to the right and down • Reverse direction
Projectile Motionobject moves in two dimensions under the gravitational force. B A • What is the accelerations at position A and B? • What is the velocities at position A and B?
A projectile launched horizontally falls in the same time as projectile that is released from rest
Ex. A ball thrown horizontally at velocity Vi , travels a horizontal distance of R m before hitting the ground. From what height was the ball thrown?(1) Since ball is thrown horizontally, Vi =VxThere is no acceleration at x direction.ie. R = Vxt, t = R/Vx(2) Viy=0, h = -1/2gt2
Problem 50 Solve a quadratic equation to get t
The maximum height and distance of fly ball For projectile motion, always remember:
Trajectories of a projectile launched at different angles with the same speed
Relative Motion • Relative position Relative velocity
Uniform Circular Motion • Period • Angular Position
Angular Velocity • Average angular velocity =∆θ/∆t • Instantaneous angular velocity • The angular velocity is constant during uniform circular motion
An old-fashioned single-play vinyl record rotates 30.0 rpm . What are (a) the angular velocity in rad/s and (b) the period of the motion? • rpm: revolution per minute. 1 rpm = 2π/60 (rad)/s
Velocity in uniform circular motion The magnitude of velocity is a constant Vt =r dθ/dt =ωr Has only a tangential Component
The magnitude of centripetal acceleration P184 Towards center of circle
Velocity and acceleration in Uniform Circular Motion The velocity has only a tangential component Vt
Nonuniform Circular Motion Change the speed Here α is angular acceleration
Rotational kinematics • For constant angular acceleration