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Vectors. Vectors. Has both Magnitude and Direction Example: “A bag of candy is located outside the classroom. To find it, displace yourself 20 meters.” What’s the problem?.
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Vectors • Has both Magnitude and Direction Example: “A bag of candy is located outside the classroom. To find it, displace yourself 20 meters.” What’s the problem?
How about…“A bag of candy is located outside the classroom. To find it displace yourself from the center of the classroom door 20 meters in a direction 30 degrees to the west of north.”
Vector Diagrams Scale Vector arrow Magnitude and direction 20 m, 30 degrees West of North
Vectors are expressed as a counterclockwise angle of rotation
Magnitude of a Vector Using the scale (1 cm = 5 miles), a displacement vector that is 15 miles will be represented by a vector arrow that is 3 cm in length. Similarly, a 25-mile displacement vector is represented by a 5-cm long vector arrow. And finally, an 18-mile displacement vector is represented by a 3.6-cm long arrow. See the examples shown below.
Example… Eric leaves the base camp and hikes 11 km, north and then hikes 11 km east. Determine Eric's resulting displacement.
Practice A Answer R2 = (5)2 + (10)2 R2 = 125 R = 11.2 km
Practice B Answer R2 = (30)2 + (40)2 R2 = 2500 R = 50 km
Stupid Ways, Important Stuff Sin = o/h Cos = a/h Tan = o/a
Practice A Tan Ɵ = (5/10) = 0.5 Ɵ= tan-1(0.5) Ɵ= 26.6 ° Direction of R = 90 °+ 26.6 ° Direction of R = 116.6 °
Practice B Tan Ɵ = (40/30) = 1.333 Ɵ= tan-1 (1.333) Ɵ= 53.1 ° Direction of R = 180 °+ 53.1 ° Direction of R = 233.1 °