图片11.png 3 .将质量为 m = 0.1 kg 的小球从地面竖直向上抛出,初速度为 v 0 = 20 m/s ,小球在运动中所受空气阻力与速率的关系为 f = kv ,已知 k = 0.1 kg/s 。其在空气的速率随时间的变化规律如图所示,取 g = 10 m/s 2 ,则以下说法正确的是 ( )
【简答题】The Pentagon(五角大楼), headquarters of the Department of Defense in US, is one of the world's largest office buildings. It is twice the size of the Merchandise Mart in Chicago, and has three times the fl...
【简答题】US Defense Secretary Donald Rumsfeld is likely to visit China at an “appropriate” time this year, a senior Chinese military official said on Monday. Colonel Tu Qiming, director of the American and Oce...