摩擦力是我们日常生活中常见的力 ,在学习摩擦力知识时 ,经常会遇到求摩擦力大小的问题。在初中阶段 ,我们仅知道在接触面相同的情况下 ,压力越大 ,摩擦力越大 ,压力越小 ,摩擦力越小 ;压力不变的情况下 ,接触面越粗糙 ,摩擦力越大 ,接触面越光滑 ,摩擦力越小 ,怎样求解这类问 Friction is a common force in our daily life. When learning friction knowledge, we often encounter the problem of the size of friction. In the junior high school stage, we only know that under the same conditions of contact surface, the greater the pressure, the greater the friction, the lower the pressure, and the smaller the friction; under the same pressure, the rougher the contact surface, the greater the friction force. The smoother the contact surface, the smaller the friction, how to solve this kind of question