1 .力臂一定都在杠杆上吗?答:力臂是从支点到力的作用线的距离———即从支点到力的作用线的垂线段的长度.如图1所示,若力的作用线与杠杆本身垂直,则从支点到力的作用线的垂线段恰好在杠杆上;如图2所示,若力的作用线与杠杆本身不垂直,力臂同样需要从支点向力的作用线作垂线,则 1. Is the arm always on the lever? A: The arm is the distance from the fulcrum to the line of force—the length of the vertical line from the fulcrum to the line of force. As shown in Figure 1, the force The line of action is perpendicular to the lever itself, and the vertical line from the fulcrum to the line of action of the force happens to be on the lever; as shown in Figure 2, if the line of force is not perpendicular to the lever itself, the arm must also move from the fulcrum to the force. The line of action acts as a vertical line, then