Physics 121 9/8/10 Prof. E. F. Redish 1 9/8/10 1 4 333cm 5cm 4cm 1 =+)(anythings 5cm 4 cm 12+ 9/8/10 9/8/10 6Physics 121 9/8/10 Prof. E. F. Redish 2 9/8/10 7 Why choose this? –concepts of measurement, rate of change,force are fundamental –ties to everyday experience so can use and learn to build/refine intuition 9/8/10 8 9/8/10 9Physics 121 9/8/10 Prof. E. F. Redish 3 9/8/10 10 iˆixrˆ=iˆ9/8/10 11 9/8/10 12 iˆ r = xˆ i + yˆ j ˆ jPhysics 121 9/8/10 Prof. E. F. Redish 4 9/8/10 13 This is like the difference between position and length! 9/8/10 14 r t()= x(t)ˆ i + y(t)ˆ j x(t) r = r t2() r t1()t = t2 t19/8/10 15 rt rt rtrrtrtrrtrtrrrrt rt rt rtrt rt() () ()() ()() ()() () () ()() ()12312 2 123 3 213 12 23213231 = = =+= + = Physics 121 9/8/10 Prof. E. F. Redish 5 9/8/10 16 o Choose origin o Choose axes o Choose scale o Set scales on graph o Take data from video 9/8/10 17 <>=<>=vvrtdisplacementtime it took to make the displacement9/8/10 18 <>= == ==+vrtvrvtrt rt v trrvtfinal initial002100() ()Position as a function of time0246810-5 0 5 10 15t (sec)x
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