6 如图,质量为m的物体,位于直立的劲度系数为k的轻弹簧正上方h高处。若物体从静止开始落向弹簧,轻弹-|||-簧的最大压缩量为() ()-|||-m-|||-h-|||-k-|||-(4.0分)-|||-A. dfrac (mg)(k)-|||-B. dfrac (mg)(2k)-|||-dfrac (mg)(k)-sqrt ({(dfrac {mg)(k))}^2+dfrac (2mgh)(k)}-|||-D dfrac (mg)(k)+sqrt ({(dfrac {mg)(k))}^2+dfrac (2mgh)(k)}-|||-bigcirc A bigcirc B ○ C ○ D