题目

Putting Movies on Mobiles Movies in the theater get their recognition at awards ceremonies such as the Oscars. But how about movies for phones? They are getting their turn at MoFilm — the first mobile film festival. The first MoFilm competition received 250 entries from more than 100 countries. Entries were restricted to films that were five minutes or less in length — ideal for viewing and sharing on mobile phones. An independent jury then selected a shortlist of five film-makers. The winner was chosen from the shortlist by an audience voting using their phones. New Platforms The awards h用绳子水平拉着重10N的物体在水平地面上以3m/s的速度做匀速直线运动，所用拉力是2N，物体所受的摩擦力的大小为 N；当拉着这个物体以5m/s的速度做匀速直线运动时，所用拉力 （大于/小于/等于）2N；当绳子突然断开时，物体将做 运动，这时所受摩擦力大小为 N． 2；等于；减速；2 【解析】 试题分析：静止的物体和匀速直线运动的物体受到平衡力的作用． 平衡力的条件：大小相等、方向相反、作用在同一条直线上，作用在同一个物体上． 摩擦力大小跟压力大小和接触面的粗糙程度有关 当拉力大于摩擦力时，物体将做加速运动；当拉力等于摩擦力时，物体将作匀速运动；当拉力小于摩擦力时，物体将作减速运动． 【解析】 物体受到10N的拉力作用，...