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1題物理題發問

發問:

我還有一個物理問題';2 particles, each with mass m=0.85kg, r fastened to each other, and to a rotation axis at 0, by two thin rods, each with length d=5.6cm and mass M=1.2kg . The combination rotates around the rotation axis with angular speed w=0.30 rad/s. measure about O, what are the combination's (a.)... 顯示更多 我還有一個物理問題'; 2 particles, each with mass m=0.85kg, r fastened to each other, and to a rotation axis at 0, by two thin rods, each with length d=5.6cm and mass M=1.2kg . The combination rotates around the rotation axis with angular speed w=0.30 rad/s. measure about O, what are the combination's (a.) rotational inertia and (b.) kinetic energy? 這題的解答是不是因該先算total mass ...然後在用公式I = mr^2 得到 inertia..然後用KE = (1/2) mv^2 得到kinetic energy?

最佳解答:

a. For the rod, its rotational inertia about O = 1/3 Md2 = 1/3 (1.2)(0.056)2 = 1.2544 X 10-3 kgm2 For the particle, its rotational inertia about O = md2 = (0.85)(0.056)2 = 2.6656 X 10-3 kgm2 So, the total rotational inertia, I = 2 X (2.6656 X 10-3 + 1.2544 X 10-3) = 7.84 X 10-3 kgm2 b. The kinetic energy of the system = 1/2 Iw2 = 1/2 (7.84 X 10-3)(0.30)2 = 3.528 X 10-4 J

其他解答:

我看過答案..好像不是呢..... 1.) 0.023 kgm2 2.) 11mj73E3DC9315AE223D