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Mechanics. AP200 Dr. C. W. Ong Meriam, J.L., Kraige, L.G., “Engineering Mechanics, Dynamics”, John Wiley Course Work 30% (Exercises and tests) Examination 70% Download materials http://ap.polyu.edu.hk/apacwong/. A. Chapter 1 Vector.
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Mechanics AP200 Dr. C. W. Ong Meriam, J.L., Kraige, L.G., “Engineering Mechanics, Dynamics”, John Wiley Course Work 30% (Exercises and tests) Examination 70% Download materials http://ap.polyu.edu.hk/apacwong/
A Chapter 1 Vector A vector has a length A and a direction (unit vector)
y x 2D Cartesian coordinate system(one form of presentation) Pythagoras theorem
z Az y Ax Ay x 3-D Cartesian coordinate system
y y x x O Addition of vectors Subtraction of vectors O
y x Dot (scalar) product of two vectors Definition: Note: AB cos = AB cos (A - B) = AB(cos A cos B +sin A sin B) = (Acos A)(Bcos B) + (Asin A) (Bsin B) In 2-D Cartesian coordination system
y O In 3-D Cartesian coordinate system: x From cosine law:
l A A’ a Application of dot product: Projection Area = l a Projected area = = l a cos
30o 60o Exercise: Find the projection of vector with a length of 10 unit along .
k j i Cross product
y x