问题 填空题

如图所示,用动滑轮将重为900N的物体匀速提升2m,不计摩擦和滑轮重,所施加的拉力F=_______N,这一过程中拉力F做功_________J。

答案

300;1800

材料分析题

(1)图中这位未成年人正面临着哪种不良诱惑?有什么危害?

                                                                                                                                                               

                                                                                                                                                               

(2)如果你是图中的他,应该怎么做

                                                                                                                                                               

(3)面对图中的诱惑,请你也给其他同学提个醒,你最想对他们说什么?

                                                                                                                                                              

                                                                                                                                                              

判断题