题目

如图1-3-9所示，GA=100 N，GB=40 N，弹簧的劲度系数为500 N/m，不计绳重和摩擦，求：物体A对支持面的压力和弹簧的伸长量.                图1-3-9 答案：解析：物体B处于静止状态，绳子拉力等于物体B的重力GB，可知弹簧拉力F也为40 N.由F=kx，得x= m=0.08 m.物体A也处于静止状态，受到重力、弹簧的弹力和支持面的支持力的作用，可知支持面对A的支持力为60 N.答案：60 N  0.08 m_ _______ , the idea of having to work under a woman defeated him. A. Wanting the job very much              B. Although wanting the job badly C. Though he wanted the job very much      D. He wanted the job badly