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 c 2 = a 2 + b 2 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: 28.6 o S of W

Finding Components of a Resultant Vector (p.92) Opposite Leg uses sin Adjacent leg uses cos Example: 8.5 m 14.7 m 17 m 30 o

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 v i 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.