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 difficult to do a sqjftch ;:0hn0f .(j7t ivzz;kit-up with your hands behi4-h :0x d)-g ylqxwo 9d)p99ymi mlpqnnd your head than when your arms are stretched out i-qq9y) wnh-x09: mx9gdppll ydi o 4)mn 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