本题目来源于试卷: gc textbook chapter 8 Rotational Motion，类别为 unclassified
[问答题]
Why is it more difficu:a;4l j 3m4rk;qeei kblt to do a sit-up with your hands3 l.+uaonh bqyk0vp 1xi,fi3t3n o 3o4 behind your head than when n+otna31k,o3pqvyh f xo33i40ib .luyour arms are stretched out in front of you? A diagram may help you to answer this.
参考答案: When you do a sit-up, torque from
your abdomen muscles must rotate the upper half of the body from a laying-down
position to a sitting-up position. The
larger the moment of inertia of the upper half of the body, the more torque is
needed, and thus the harder the sit-up is to do. With the hands behind the head, the moment of
inertia of the upper half of the body is larger than with the hands
outstretched in front.
本题详细解析:
暂无
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Post time 2025-2-18 20:00:22