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This chapter explores vector addition, velocity, acceleration, projectile motion, and relative velocity in two dimensions. Learn geometric and algebraic methods, trigonometry, and vector properties. Understand projectile motion, relative motion, and kinematic equations in two dimensions. Develop knowledge on displacement, velocity, and acceleration components, and their applications in various scenarios.
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Chapter 3: Motion in a Plane • Vector Addition • Velocity • Acceleration • Projectile motion • Relative Velocity • CQ: 1, 2. • P: 3, 5, 7, 13, 21, 31, 39, 49, 51.
Two Dimensional Vectors Displacement, velocity, and acceleration each have (x, y) components Two methods used: geometrical (graphical) method algebraic (analytical) method / 2
Addition Example • Giam (11)
0 Order Independent (Commutative)
0 Subtraction, tail-to-tail
Subtraction Example • Giam (19)
Algebraic Component Addition • trigonometry & geometry • “R” denotes “resultant” sum • Rx = sum of x-parts of each vector • Ry = sum of y-parts of each vector
Examples • Magnitude || (g4-5) Notation, Example • Component Example Animated • Phet Vectors
h o q a 0 Trigonometry
0 Using your Calculator: Degrees and Radians Check this to verify your calculator is working with degrees
h o q a Example: 0 • Given: • = 10°, h = 3 Find o and a.
Determine angle from length ratios. Ex. o/h = 0.5: Ex. o/a = 1.0: 0 Inverse Trig
h o q a 0 Pythagorean Theorem Example: Given, o = 2 and a = 3 Find h
0 Azimuth: Angle measured counter-clockwise from +x direction. Examples: East 0°, North 90°, West 180°, South 270°. Northeast = NE = 45°
0 Check your understanding: What are the Azimuth angles? A: 180° 60° B: 70° C: 110° Note: All angles measured from east.
0 Components: Given A = 2.0m @ 25°, its x, y components are: Check using Pythagorean Theorem:
Example Vector Addition 0 R = (10cm, 0°) + (10cm, 45°):
0 (cont) Magnitude, Angle:
0 General Properties of Vectors • size and direction define a vector • location independent • change size and/or direction when multiplied by a constant • Vector multiplied by a negative number changes to a direction opposite of its original direction. • written: Bold or Arrow
0 these vectors are all the same
A 0.5A -A -1.2A Multiplication by Constants 0
Projectile Motion • time = 0: e.g. baseball leaves fingertips • time = t: e.g. baseball hits glove • Horizontal acceleration = 0 • Vertical acceleration = -9.8m/s/s • Horizontal Displacement (Range) = Dx • Vertical Displacement = Dy • Vo = launch speed • qo = launch angle
0 Range vs. Angle
Example 1: 6m/s at 30 0 vo = 6.00m/s qo = 30° xo = 0, yo = 1.6m; x = R, y = 0 27
Example 1 (cont.) 0 Step 1 28
Quadratic Equation 0 29
Example 1 (cont.) 0 End of Step 1 30
Example 1 (cont.) 0 Step 2 (ax = 0) “Range” = 4.96m End of Example 31
Relative Motion • Examples: • people-mover at airport • airplane flying in wind • passing velocity (difference in velocities) • notation used:velocity “BA” = velocity of B – velocity of A
Summary • Vector Components & Addition using trig • Graphical Vector Addition & Azimuths • Projectile Motion • Relative Motion
0 R = (2.0m, 25°) + (3.0m, 50°): 34
0 (cont) Magnitude, Angle: 35
0 PM Example 2: vo = 6.00m/s qo = 0° xo = 0, yo = 1.6m; x = R, y = 0
0 PM Example 2 (cont.) Step 1
0 PM Example 2 (cont.) Step 2 (ax = 0) “Range” = 3.43m End of Step 2
v1 0 1. v1 and v2 are located on trajectory. a
Q1. Given locate these on the trajectory and form Dv. 0
0 Kinematic Equations in Two Dimensions * many books assume that xo and yo are both zero.
0 Velocity in Two Dimensions • vavg // Dr • instantaneous “v” is limit of “vavg” as Dt 0
0 Acceleration in Two Dimensions • aavg // Dv • instantaneous “a” is limit of “aavg” as Dt 0
0 Conventions • ro = “initial” position at t = 0 • r = “final” position at time t.
Dr ro r 0 Displacement in Two Dimensions
Acceleration ~ v change • 1 dim. example: car starting, stopping
Ex. Vector Addition • Add A = 3@60degrees azimuth, plus B = 3@300degrees azimuth. • Find length of A+B, and its azimuth. Sketch the situation.
Ex.2: • 10cm@10degrees + 10cm@30degrees • Length and azimuth?