1 问题 如图1所示,在水平正交的匀强电场和匀强磁场中,E=4 V/m,B=2 T,质量m=1g的带正电的小物块A,从绝缘粗糙的竖直壁的M点无初速下滑,当它滑行h=0.8 m到达N点时离开壁做曲线运动。当A运动到P点时恰好处于平衡状态,此时速度方向与水平方向成45°角,若P与M的高度差H=1.6 m,求:①A沿壁下滑时的摩擦力做的功;②P与M间的水平距离为多少?(g=10 m/s~2) 1 The problem is shown in Figure 1. In a horizontally-homogeneous homogeneous electric field and uniform magnetic field, E = 4 V/m, B = 2 T, mass m = 1g, positively charged small block A, from rough insulation The M point of the vertical wall does not slide at the muzzle velocity and leaves the wall to do a curvilinear motion when it slides h=0.8 m to reach point N. When A moves to point P, it is in an equilibrium state. At this time, the direction of the speed is at an angle of 45° with the horizontal direction. If the height difference between P and M is H=1.6 m, then the friction of 1A along the wall is required to do the work. What is the horizontal distance between 2P and M?(g=10 m/s~2)