gc textbook chapter 8 Rotational Motion (id: 023a5d902)

admin

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,iud b ,de-c /ephou( vp+x)h0ltlm6xl2asv:j 08fd v9m to do a sit-up with your hands behind your head than when your arms are stretched out in front vfm9d:jm86a lx2svl0of 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