Why is it more difficult to do sit-ups when your knees are bent than when your legs are stretched out?
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In the first case, the knees are bent, only abdomen muscles provide torque around hip in counterclockwise.
In the second case, the legs are stretched. Front leg muscles also provide torque around the hip in counterclockwise direction with the abdomens.
It is easier to do sit-ups when the legs are stretched.
Textbook: Physics: Principles with Applications
Author: Douglas C. Giancoli
Physics: Principles with Applications was written by and is associated to the ISBN: 9780130606204. This full solution covers the following key subjects: Bent, difficult, knees, Legs, SIT. This expansive textbook survival guide covers 35 chapters, and 3914 solutions. Since the solution to 15Q from 9 chapter was answered, more than 475 students have viewed the full step-by-step answer. The full step-by-step solution to problem: 15Q from chapter: 9 was answered by , our top Physics solution expert on 03/03/17, 03:53PM. The answer to “Why is it more difficult to do sit-ups when your knees are bent than when your legs are stretched out?” is broken down into a number of easy to follow steps, and 20 words. This textbook survival guide was created for the textbook: Physics: Principles with Applications, edition: 6.