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Chapter 3. 2-D Kinematics. Vectors. Quantities described by a magnitude and a direction Displacement, velocity, acceleration, force, momentum, etc. Can be represented as an arrow Length of the arrow = magnitude Angle of the arrow = direction. Vector Addition.
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Chapter 3 2-D Kinematics
Vectors • Quantities described by a magnitude and a direction • Displacement, velocity, acceleration, force, momentum, etc. • Can be represented as an arrow • Length of the arrow = magnitude • Angle of the arrow = direction
Vector Addition • You cannot just add or subtract magnitudes, unless they are directly aligned or directly opposed • To add, draw them tip to tail • The total, “resultant,” vector is drawn from the very beginning to the very end
Vector components • Each vector can be treated as the hypotenuse of a right triangle • Every vector is the resultant of a horizontal and vertical component vector
Adding by components • Find components of all vectors • Rx = Ax + Bx + . . . • Ry = Ay + By + . . . • R2 = Rx2 + Ry2 • tan = Ry/Rx
Relative Velocity • All vectors are measured in reference to a particular place, called a ‘reference frame’
Projectile Motion • Falling through the air while moving horizontally • Constant velocity horizontally • Constant acceleration (-9.8 m/s2) vertically • Only consider moment just after launch to the moment just after landing • Projectiles follow parabolic paths
Projectile Motion • X and Y motions are completely separate • Time is a scalar, so it’s the same for both • Do kinematics separately for each x = vix = vfx = ax = 0 t = y = viy = vfy = ay = -9.8 m/s2 t =