Q15. When you are sitting on a chair, your center of mass (CM) is over the seat of the chair. If you push upward with your feet without leaning forward, your weight will cause a torque that will rotate your body backwards around your feet and into the chair. You can avoid this by first leaning forward so your CM is over your feet. Then when you push up with your feet your weight will not exert a torque to rotate your body and you can rise. (Make sketches of the two situations to see this graphically.)
Return to the top of the: