题目

Pepper works in a supermarket in Germany. He is different from other employees (雇员). Pepper is a robot that looks like a human.A Japanese company made Pepper in 2014. Pepper is as tall as a 6-year-old kid. He has cameras. They help him recognize things around him. There are wheels under his body. They help Pepper move.The robot can do a lot of things. He can read people's emotions (感情) and communicate with people. He can also teach students about programming.【1】What does Pepper look like?A.A human. B.A robot. C.An animal.【2】What does Pepper use to recognize things around him?A.13．如图，xoy平面内存在着沿y轴正方向的匀强电场，一个质量为m、带电荷量为+q的粒子从坐标原点O以速度v0沿x轴正方向开始运动．当它经过图中虚线上的M（2$\sqrt{3}$a，a）点时，撤去电场，粒子继续运动一段时间后进入一个矩形匀强磁场区域（图中未画出），又从虚线上的某一位置N处沿y轴负方向运动并再次经过M点．已知磁场方向垂直xoy平面（纸面）向里，磁感应强度大小为B，不计粒子的重力．试求：（1）电场强度的大小；（2）N点的坐标；（3）矩形磁场的最小面积．