手枪从地面垂直向上射出子弹，子弹在30 s后掉回地面。子弹发射时的速率是多少？ 用枪竖直向上射出一子弹，设空气阻力与子弹速度大小成正比，子弹...
\u5b50\u5f39\u4ece\u67aa\u53e3\u5c04\u51fa\u901f\u5ea6\u5927\u5c0f\u662f30 m/s\uff0c\u67d0\u4eba\u6bcf\u96941s\u7ad6\u76f4\u5411\u4e0a\u5f00\u67aa\uff0c\u5047\u5b9a\u5b50\u5f39\u5728\u5347\u964d\u8fc7\u7a0b\u4e2d\u90fd\u4e0d\u76f8\u78b0\uff0c\u4e0d\u8ba1\u7a7a\u6c14\u963b\u529b\uff081\uff096\u9897\u5b50\u5f39\uff082\uff09t 12 =3.5s\u65f6\uff0c\u7b2c\u4e8c\u9897\u5b50\u5f39\u4e0e\u7b2c\u4e00\u9897\u5b50\u5f39\u7a7a\u4e2d\u76f8\u9047\uff08t 12 \u8868\u793a\u7b2c1\u9897\u5b50\u5f39\u4e0e\u7b2c2\u9897\u5b50\u5f39\u5728\u7a7a\u4e2d\u76f8\u9047\u7684\u65f6\u95f4\uff0c\u4ee5\u540e\u7c7b\u4f3c\uff09\uff0c\u4ee5\u540e\u6bcf\u96940.5s\u7b2c\u4e09\u9897\u3001\u7b2c\u56db\u9897\u3001\u7b2c\u4e94\u9897\u3001\u7b2c\u516d\u9897\u4e0e\u7b2c\u4e00\u9897\u5b50\u5f39\u7a7a\u4e2d\u76f8\u9047\uff0c\u6545\u7a7a\u4e2d\u76f8\u9047\u7684\u65f6\u523b\u5206\u522b\u4e3at 13 =4.0s\uff1bt 14 =4.5s\uff1bt 15 =5.0s\uff1bt 16 =5.5s\u3002\uff083\uff0913.75m \u2474\u4e00\u9897\u5b50\u5f39\u4ece\u5c04\u51fa\u5230\u843d\u56de\u5730\u9762\u5171\u7528\u65f6\uff1a s=6s\uff0c\u56e0\u67d0\u4eba\u6bcf\u96941s\u7ad6\u76f4\u5411\u4e0a\u5f00\u67aa\uff0c\u4e14\u5047\u5b9a\u5b50\u5f39\u5728\u5347\u964d\u8fc7\u7a0b\u4e2d\u90fd\u4e0d\u76f8\u78b0\uff0c\u4e0d\u8ba1\u7a7a\u6c14\u963b\u529b\uff0c\u6545\u5f53\u7b2c\u4e00\u9897\u5b50\u5f39\u521a\u7740\u5730\u65f6\uff0c\u7b2c\u4e03\u9897\u5b50\u5f39\u521a\u53d1\u51fa\uff0c\u7a7a\u4e2d\u6700\u591a\u80fd\u67096\u9897\u5b50\u5f39\u3002\u2475\u7531\u9898\u610f\u5206\u6790\u77e5\uff0c\u5f53 t \uff1d3 s\u65f6\u7b2c\u4e00\u9897\u5b50\u5f39\u5230\u8fbe\u6700\u9ad8\u70b9\uff0c\u8fd9\u65f6\u7b2c\u4e8c\u9897\u5b50\u5f39\u79bb\u6700\u9ad8\u70b9\u7684\u8ddd\u79bb\u4e3a5m\uff0c\u901f\u5ea6\u4e3a10m/s\uff0c\u8fd9\u4ee5\u540e\u7b2c\u4e8c\u9897\u5b50\u5f39\u76f8\u5bf9\u7b2c\u4e00\u9897\u5b50\u5f39\u4ee510m/s\u7684\u901f\u5ea6\u5300\u901f\u8fd0\u52a8\uff0c\u5230\u7b2c\u4e8c\u9897\u5b50\u5f39\u4e0e\u7b2c\u4e00\u9897\u5b50\u5f39\u7a7a\u4e2d\u76f8\u9047\u8fd8\u9700\uff1a s=0.5s\uff0c\u6240\u4ee5\uff0c\u5f53t 12 =3.5s\u65f6\uff0c\u7b2c\u4e8c\u9897\u5b50\u5f39\u4e0e\u7b2c\u4e00\u9897\u5b50\u5f39\u7a7a\u4e2d\u76f8\u9047\uff08t 12 \u8868\u793a\u7b2c1\u9897\u5b50\u5f39\u4e0e\u7b2c2\u9897\u5b50\u5f39\u5728\u7a7a\u4e2d\u76f8\u9047\u7684\u65f6\u95f4\uff0c\u4ee5\u540e\u7c7b\u4f3c\uff09\uff0c\u4ee5\u540e\u6bcf\u96940.5s\u7b2c\u4e09\u9897\u3001\u7b2c\u56db\u9897\u3001\u7b2c\u4e94\u9897\u3001\u7b2c\u516d\u9897\u4e0e\u7b2c\u4e00\u9897\u5b50\u5f39\u7a7a\u4e2d\u76f8\u9047\uff0c\u6545\u7a7a\u4e2d\u76f8\u9047\u7684\u65f6\u523b\u5206\u522b\u4e3at 13 =4.0s\uff1bt 14 =4.5s\uff1bt 15 =5.0s\uff1bt 16 =5.5s\u3002\u2476\u76f8\u9047\u70b9\u7684\u4f4d\u7f6e\u5c31\u662f\u7b2c\u4e00\u9897\u5b50\u5f39\u7a7a\u4e2d\u4f4d\u7f6e\uff0c\u7531\u4e8e\u7b2c\u4e00\u9897\u5b50\u5f39\u5f53 t \uff1d3 s\u65f6\u5230\u8fbe\u6700\u9ad8\u70b9\uff0c\u5f53t 12 =3.5s\uff1bt 13 =4.0s\uff1bt 14 =4.5s\uff1bt 15 =5.0s\uff1bt 16 =5.5s\u4e0e\u5176\u4ed6\u5b50\u5f39\u76f8\u9047\u65f6\uff0c\u7b2c\u4e00\u9897\u5b50\u5f39\u4e0b\u843d\u7684\u9ad8\u5ea6\u5206\u522b\u4e3a\uff1a \uff1d m=1.25m\uff0c m\uff0c m\uff0c m\uff0c m\uff0c\u7b2c\u4e00\u9897\u5b50\u5f39\u4e0a\u5347\u7684\u6700\u5927\u9ad8\u5ea6\u4e3a\uff1a m=45m\uff0c\u6240\u4ee5\u8fd9\u4e9b\u5b50\u5f39\u4e0e\u7b2c\u4e00\u9897\u5b50\u5f39\u76f8\u9047\u7684\u9ad8\u5ea6\u5206\u522b\u4e3a\uff1ah 12 = \uff1d43.75m\uff1bh 13 = \uff1d40m\uff1bh 14 = \uff1d33.75m\uff1bh 15 = \uff1d25m\uff1bh 16 = \uff1d13.75m\u3002
\u5728\u4e0a\u5347\u8fc7\u7a0b\u4e2d\uff0c\u901f\u5ea6\u4e0d\u65ad\u51cf\u5c0f\uff0c\u5219\u963b\u529b\u4e0d\u65ad\u51cf\u5c0f\uff0c\u6839\u636ea= F \u5408 m = mg+f m \u77e5\uff0c\u52a0\u901f\u5ea6\u4e0d\u53d8\u51cf\u5c0f\uff0e\u5728\u4e0b\u964d\u7684\u8fc7\u7a0b\u4e2d\uff0c\u901f\u5ea6\u4e0d\u65ad\u589e\u5927\uff0c\u963b\u529b\u4e0d\u65ad\u53d8\u5927\uff0c\u6839\u636ea= F \u5408 m = mg-f m \u77e5\uff0c\u52a0\u901f\u5ea6\u4ecd\u4e0d\u65ad\u53d8\u5c0f\uff0e\u6545\u51fa\u67aa\u53e3\u65f6\u7684\u52a0\u901f\u5ea6\u6700\u5927\uff0c\u843d\u56de\u5c04\u51fa\u70b9\u65f6\u52a0\u901f\u5ea6\u6700\u5c0f\uff0c\u5728\u6700\u9ad8\u70b9\u65f6\u7684\u52a0\u901f\u5ea6\u4e3ag\uff0c\u6545\u2460\u2463\u6b63\u786e\uff0c\u2461\u2462\u9519\u8bef\uff0e\u6545\u9009D\uff0e
这种理想状态下只跟重力加速度有关，设初速度为V₀，V=V₀+at，重力加速度方向恒为垂直向下，所以上升段t₁=－（V-V₀）/g=V₀/g——V为0,下降段V₀=gt₂→t₂=V₀/g，（下降时初速度为0）,由此推出t₁=t₂，t=t₁+t₂=30s，V₀=gt₁=9.8×15m/s=147m/s看你这把手枪的初速和射程喔。还得考虑风向和阻力，只能理论猜想吧，说不准的
考虑不考虑空气的阻力
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