文档介绍：Rotational ic Energy ??? 22 1 iivm K????? 22 1 iirm?.2 1 2??IK 1. The ic Energy of Rotation: 10-10 Rotational ic Energy (P254) 22)(2 1???? iirm ?. ?????????????? y?T ????????????????- ????????????????ddrF???rdFdW ???? ds F? cos ????rd ? F ??r ???? rd F cos ?????dId dt dI?????? fi fidIdW ????????? KII if???? 222 12 1??—– In rotation, work is the accumulation of the torque with respect to angular space (转动中功是力矩对角空间的累积). —– the power for rotational motion dt dW P? By analogy, The effect is changing the rotational ic energy (其效果是改变转动能).dt d???????. ????- ????? y ????????????????????- ????????????? The principle of work-energy for particle- systems still holds for the rigid bodies. mec iiffi nc extEUKUKW W???????)()(iiff nc extUKUK W W when i??????0 The law of conservation of mechanical energy is also valid. ????????? For the spring, k = ?10 3 N/m ; For the wheel: I = kg ?m 2 , R =30cm ; m Rk What is the speed of the body ( m =60kg ), when it falls 40cm . Initially, it is at rest and the spring is not stretched. on) translati : block ( ma T mg?? rotation) : (wheel ?I kxR TR?? slip) no (?Ra? EXAMPLE: xRIm kx mg vv hvd/ d 02 0????? m/s / 2 2 2????RIm kh mgh v or, using the law of conservation of mechanical energy 22 1kh mgh ? 22 1?I? 22 1 mv ? t vad d?dx vvdt xdx vddd?? 2/RIm kx mg a???----mended m Rk 10-4 Vector Nature of