1、选择题  人用手竖直地握着啤酒瓶，始终保持静止，则（　　）
A．手握瓶子的力越大，手与瓶子间的摩擦力就越大
B．往瓶子加水后，手与瓶子间的摩擦力将增大
C．手握瓶子的力大小等于手与瓶子间的摩擦力
D．若手握瓶子的力大小为FN，手与瓶子间的动摩擦因素为μ，则手与瓶子间的摩擦力大小为μFN

2、选择题  如图所示，用三根轻绳将质量均为m的A、B两小球以及水平天花板上的固定点O之间两两连接．然后用一水平方向的力F作用于A球上，此时三根轻绳均处于直线状态，且OB绳恰好处于竖直方向，两球均处于静止状态．三根轻绳的长度之比为OA：AB：OB=3：4：5．则下列说法正确的是（　　）
A．OB绳中的拉力小于mg
B．OA绳中的拉力大小为style="shiti/data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAkAAAAmCAIAAACZCSakAAAAqUlEQVQ4jc2TsREDIQwE1QVlEFCEqyBRDy6CRLWQqBMl6kBd4ICfB2TeDjxj+9IdiTs4oF0LPmWa4BAWXhiXO4tt5zRn2u/USn0bVfVMRFprJhwAQkSb2STDGM5pn0EreZ/vmQlHdx7lI/dsZLPTZ/gqe6Wf+DSM4fl5+33eelm0EkDSiZmMFmla2anl0Qfb1mnxyQVn7DNQTpd9oZz2cyYcVp/jl/xxXx5I13o5uLygQQAAAABJRU5ErkJggg==" alt="">mg
C．拉力F大小为style="shiti/data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAkAAAAkCAIAAADUwYevAAAAmUlEQVQokb2SsQ3DMAwEfwuPkUJDeAo22kFDqOEsariJGm7ALZzCUALTFODEgL89PPkPEttcuMSk5kQcMG0MIGRKxKHP8mvVcKbUIt3ifaXKNMtJSX/ocIOd9Tib6f+Zeifn/hAAgGW/5YdZoWKhTxtz0whtYErupF/Wx7MAyOM/fE7rshzdhw5Mq8t5gUnNfl8atR3wMx9gb1+ERpQbGZxtAAAAAElFTkSuQmCC" alt="">mg
D．拉力F大小为style="shiti/data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAcAAAAkCAIAAADKCLccAAAAlElEQVQokbWSsQ3EMAhF2cJjuPAQmcINO3gIN8yShk3csAFbkCLnOx+xFDlSqNADf9DHYLOAG8oVU6Y/KjsBgKOSM7lexbiJU+BauKnXLZUn0y6R5GazRbriw2M6j7emaeMwuPWhW0Q1MzPK6eeD9rrs5N3RxmFUON963Z4oxvAtjJtJgnDe29FL7/zy2D/Gqg8L9ABLQ2zGAEjbPgAAAABJRU5ErkJggg==" alt="">mg