一个圆柱形的饮料瓶如题15图所示，其容积为300mL．现瓶内装有一些饮料．该瓶正放时，饮料高度为20cm，若该瓶倒放时，空余部分的高度为5cm，瓶内现有饮料的体积为()cm3．<img src='https://img2.soutiyun.com/shangxueba/ask/1560001-1563000/1562230/ct_kgctem_kgctechoose_0115(106)1.jpg' />

A . F=B B . F=1 C . F=A D . F=0

A . 保持 B . 置0 C . 置1 D . 计数

<img src='https://img2.soutiyun.com/ask/2020-07-10/963227378433887.png' />

<img src='https://img2.soutiyun.com/ask/2020-09-23/969708653604874.png' />

对于 如题3-6图所示的三角波信号，试证明其频谱函数为<img src='https://img2.soutiyun.com/ask/2020-07-10/963220577029868.png' />。 <img src='https://img2.soutiyun.com/ask/2020-07-10/963220592031727.png' />

<img src='https://img2.soutiyun.com/ask/2020-11-19/974672581503885.png' />

(1)此时的加速度a应为多少？ (2)分别计算容器以匀速前进及以加速度a前进时B点的压强. <img src='https://img2.soutiyun.com/ask/2020-09-23/969707834182006.png' />

<img src='https://img2.soutiyun.com/ask/2021-01-06/978773311343442.png' />

<img src='https://img2.soutiyun.com/ask/2020-07-10/96322419439877.png' />

(2)当u取什么值时,水流作功最大？ <img src='https://img2.soutiyun.com/ask/2020-09-24/969810685156885.jpg' />

如题[84]图所示为水电站压力输水管,其直径d=1m,静水头h=100m,试求:(1)当钢管的允许拉应力[σ]=1.37×10⁵kN/m³时,管壁的厚度δ.(2)当管壁的厚度δ=5mm时,管壁的环向与轴向拉应力. <img src='https://img2.soutiyun.com/ask/2020-09-23/96971114423233.jpg' />

<img src='https://img2.soutiyun.com/ask/2020-09-23/969711107286217.jpg' />

<img src='https://img2.soutiyun.com/ask/2020-11-20/974757451637506.png' />

由下式给出：<img src='https://img2.soutiyun.com/ask/2020-07-14/963589443855635.png' />。 分析:应用安培环路定理求解。注意环路中电流的计算，应该是先求出载流导体内电流密度，再求出穿过环路的电流。 <img src='https://img2.soutiyun.com/ask/2020-07-14/963589465464871.png' />

<img src='https://img2.soutiyun.com/ask/2020-10-06/97086491567492.png' />

<img src='https://img2.soutiyun.com/ask/2021-01-13/979382023144195.png' />

如题4-37图所示，一长为<img src='https://img2.soutiyun.com/ask/2020-11-19/974670601200382.png' />、质量为m的均匀细棒，在光滑的平面上绕质心作无滑动的转动，其角速度为ω。若棒突然改绕其一端转动，求：(1)以端点为转轴的角速度ω';(2)在此过程中转动动能的改变。 <img src='https://img2.soutiyun.com/ask/2020-11-19/974670608244785.png' />

圆柱筒直径d=2m,长L=1m,重G=19.5kN,静止于贮液容器中,如题[80]图所示,容器中有两种液体,γ=(2/3)γ₂=8kN/m³.h₁=h₂=1m,求切点A和B的支座反力R_A、和R_B. <img src='https://img2.soutiyun.com/ask/2020-09-23/969710974601628.jpg' />

<img src='https://img2.soutiyun.com/ask/2020-07-14/963588454692058.png' /> 分析:微分半圆柱形金属薄片，对微分电流dI应用无限长载流直导线产生的磁场公式求解 。 并将场强矢量<img src='https://img2.soutiyun.com/ask/2020-07-14/963588473652142.jpg' />分解后再积分求解总的磁感应强度。注意利用场的对称性。

(1)ab两端的电势差: (2)cd两点电势高低的情况， <img src='https://img2.soutiyun.com/ask/2020-12-28/978022070269893.png' />

<img src='https://img2.soutiyun.com/ask/2020-09-22/969646123404023.png' />

0.6m,试求盖板.上受到的总压力。 <img src='https://img2.soutiyun.com/ask/2020-07-21/964193669351486.png' />

<img src='https://img2.soutiyun.com/ask/2020-09-23/969707515317768.png' />