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Chapter 3 . Test Review. Scalar. A physical quantity that has only a magnitude but NO direction. Vector. A physical quantity that has both a magnitude AND a direction. Scalar/Vector Examples. Scalar Examples speed time a count (how many jelly beans in the jar) mass volume
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Chapter 3 Test Review
Scalar • A physical quantity that has only a magnitude but NO direction.
Vector • A physical quantity that has both a magnitude AND a direction.
Scalar/Vector Examples • Scalar Examples speed time a count (how many jelly beans in the jar) mass volume temperature • Vector Examples velocity acceleration force displacement
Properties of Vectors (p.86) • Vectors can be added in any order. 30 m/s + 30 m/s = 60 m/s • To subtract a vector, add its opposite. v + (-v) = 30 m/s + (-30 m/s) = 0 m/s Example: A motorized sailboat is going 20 m/s against a 5 m/s wind, what is the resultant velocity? Answer: 15 m/s
Finding the Resultant Vector (p.90) • Use Pythagorean Formula c2 = a2 + b2 • Find angle using inverse trig functions: cos-1 sin-1 tan-1 Example: Michelle walks 8m west, 6m south, then 3m west. What straight-line displacement could she have taken? Answer: 12.5m @ 28.6o S of W
Finding Components of a Resultant Vector (p.92) • Opposite Leg uses sin • Adjacent leg uses cos Example: 17 m 8.5 m 30o 14.7 m
Projectiles • Projectiles follow the path of a parabola (parabolic). • Projectiles are objects that are thrust forward with no means of self-propulsion (after being launched). • Objects that are dropped “straight down” with no velocity component in the x-direction are not “thrust forward” and therefore are not considered to be projectiles. • Projectiles launched horizontally have a vi in the y-direction of 0 m/s. • At the peak of a projectile’s flight, the velocity in the y-direction is 0 m/s.
Relative Motion • Read pages 106 & 107 in your book. • The problem on the test will only be one-dimensional. • There is NO equation or formula.