-
手机是常用通信工具,当来电话时,可以用振动来提示人们,振动原理很简单:是一个微型电动机带动转轴上的叶片转动.当叶片转动后,电动机就跟着振动起来了,从而带手机振动起来,其中叶片的形状你认为是图中的哪种( )
A.![](https://img.xintiku.com/upload/49/c6/49c6ac1ab8aff2687316f3714a7b4f85.png)
B.![](https://img.xintiku.com/upload/0b/21/0b2185e419e737ccd367b55785eefc1a.png)
C.![](data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACsAAAA1CAYAAADYgRIrAAAAAXNSR0IArs4c6QAAAARnQU1BAACx
jwv8YQUAAAAJcEhZcwAADsMAAA7DAcdvqGQAAAb4SURBVGhDzZhbbE1pFMdPQjru2rrfiqLEpY1L
XIIaiaE8NDEJQkmESLy1D8xDx5h4QaM1+uDBPNB4QDuYxANBQ+g80BcxWjyJdEjcm4hWS1nT39K1
83V39/Sc043+k5V9OXt/32//91rf9+0TkQT1+fNnaW5ulg8fPnjHtm+yc2zDUNywBmnx6dMnb7+p
qUm3BmjnwlJCsO/fv/dAXTc5Bo7gvD3Id3MWGZS5aPr48aOCEQb6XZ31q7GxUYqKimT16tW6j+wh
eoSzJlwrLi6RgQMHSlpampw7d07Pu5DfBNY6dIPXbLp27Zrk5OTI9OnTZfjw4TJx4kRZujRbzp//
W+HclAhLUWFxzi0m6/jixYsyfvx4GTZsmIwbN04mT56sx7ibn1+g13At97k53V11CtvS0qKd0Sn7
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kn7QRRJLSB4gKSlJXz1T79OnT5UDNwlASQWF5YQBo1evXklh4a/qQFCHiQRQTK/5+flSXV0tR48e
lcWLF0tmZqbMnj27dUW2TPbt26dvFcFinz825bbLWYAJdOXKFZk1a5Z2EtR5PMHbYZ3BNHv1aqW2
j6h2ZstLly61rnX/bTv7xVFg3S3yYHHY5mB07949WbhwoSZ8EECsASivuU+fPrJ9+3bPjCBZbnKN
uwWWWtI08IMiVj6FhYWaS0EQsQYPyyJl1aocefbsmbZt1Q0AW9vnvEHaeYJzMHqwXMzW1YMHDyQr
K8vr1A/SVZirpEBV1T/apnUOkAG64pjzruxc4DiL+JHEPnbsTx3C4oUFdOzYsbqCOnTokEKao8D6
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oy5hm5qa5cyZ8lbQDJ0kguD8Qcrg6ooVP3kzkbVnsJaz8ahTWERj1uDJkyc1/4CI5rCNqVxz+3a1
3otw0iL0nEW4QZHRcENDQ+tH5GGFZXAPAiWvAeXbbdeuXV4b3G+gKKjiY1HUAuNV4QKNI46Li4tl
xowZCu0WnVU/n+9bt26Vly9fahuJggUpKiz5RVi+mcrLKzQvAXOBgZ0/f773Ke0+aBjqMg2sQ1wF
HL17904OHDig/2GREuQnn9YpKck663EdD8trtzQKQ13C0rF1ag7b6z1ypFRXUjjMgmfZsh/lxo0b
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AABJRU5ErkJgguiPgeS8mOe9kQ==
)
D.
-
手机是常用通信工具,当来电话时,可以用振动来提示人们,振动原理很简单:是一个微型电动机带动转轴上的叶片转动.当叶片转动后,电动机就跟着振动起来了,从而带手机振动起来,其中叶片的形状你认为是图中的哪种( )
A.![](https://img.xintiku.com/upload/e5/08/e508efb3aaf76e088348b40a5b3c5734.png)
B.![](https://img.xintiku.com/upload/4e/cb/4ecb2aa25401083beb4bc235fce58ed3.png)
C.![](data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACsAAAA1CAYAAADYgRIrAAAAAXNSR0IArs4c6QAAAARnQU1BAACx
jwv8YQUAAAAJcEhZcwAADsMAAA7DAcdvqGQAAAb4SURBVGhDzZhbbE1pFMdPQjru2rrfiqLEpY1L
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83V39/Sc043+k5V9OXt/32//91rf9+0TkQT1+fNnaW5ulg8fPnjHtm+yc2zDUNywBmnx6dMnb7+p
qUm3BmjnwlJCsO/fv/dAXTc5Bo7gvD3Id3MWGZS5aPr48aOCEQb6XZ31q7GxUYqKimT16tW6j+wh
eoSzJlwrLi6RgQMHSlpampw7d07Pu5DfBNY6dIPXbLp27Zrk5OTI9OnTZfjw4TJx4kRZujRbzp//
W+HclAhLUWFxzi0m6/jixYsyfvx4GTZsmIwbN04mT56sx7ibn1+g13At97k53V11CtvS0qKd0Sn7
wKLKykqZN2+epKSkSHp6eruYMGGCZGVlysGDB9VZgocNS53C2iskACUuX74sCxYskFGjRsmkSZM6
wBJDhw5Vpy1l7CHDUNQCA9SGHip99+5fJBKJBEJakAojR46ULVu2yP379/XesBQ1Z8k3gBsaGltf
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y1+EARbxPkgHWBpw8+zhw4etA/4aGT16dEygBO5yPePv8eMntB3apG2KlqIjug3r182bN7VT3AoC
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kn7QRRJLSB4gKSlJXz1T79OnT5UDNwlASQWF5YQBo1evXklh4a/qQFCHiQRQTK/5+flSXV0tR48e
lcWLF0tmZqbMnj27dUW2TPbt26dvFcFinz825bbLWYAJdOXKFZk1a5Z2EtR5PMHbYZ3BNHv1aqW2
j6h2ZstLly61rnX/bTv7xVFg3S3yYHHY5mB07949WbhwoSZ8EECsASivuU+fPrJ9+3bPjCBZbnKN
uwWWWtI08IMiVj6FhYWaS0EQsQYPyyJl1aocefbsmbZt1Q0AW9vnvEHaeYJzMHqwXMzW1YMHDyQr
K8vr1A/SVZirpEBV1T/apnUOkAG64pjzruxc4DiL+JHEPnbsTx3C4oUFdOzYsbqCOnTokEKao8D6
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oy5hm5qa5cyZ8lbQDJ0kguD8Qcrg6ooVP3kzkbVnsJaz8ahTWERj1uDJkyc1/4CI5rCNqVxz+3a1
3otw0iL0nEW4QZHRcENDQ+tH5GGFZXAPAiWvAeXbbdeuXV4b3G+gKKjiY1HUAuNV4QKNI46Li4tl
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HL17904OHDig/2GREuQnn9YpKck663EdD8trtzQKQ13C0rF1ag7b6z1ypFRXUjjMgmfZsh/lxo0b
+oDcxzXfJA2QuYOrbOnYjk18CbNI4T+GW7du6zl7QMKfQt1RVFhXgBsEAtycZ5Rwq9+uQex/E2c7
E53bgtiVHzRsxQ1rqUFYTpKjFmG+dr8SggUQ2ThsYbn9tZRQGpgsHQhy9+tK5H+N5wsY3FXojgAA
AABJRU5ErkJgguiPgeS8mOe9kQ==
)
D.
-
手机是常用通信工具,当来电话时,可以用振动来提示人们,振动原理很简单:是一个微型电动机带动转轴上的叶片转动.当叶片转动后,电动机就跟着振动起来了,从而带手机振动起来,其中叶片的形状你认为是图中的哪种( )
A.![](https://img.xintiku.com/upload/6a/12/6a128d3c1037084bdbdbd0c2c6fe07b9.png)
B.![](https://img.xintiku.com/upload/5c/20/5c20df13407e6b400c820a4ea8690d5f.png)
C.![](data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACsAAAA1CAYAAADYgRIrAAAAAXNSR0IArs4c6QAAAARnQU1BAACx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XZ1+Qw0YMCB0d/lGY2FOu27bGMMxoDt27PBAEa4yi+lCBkgqjkAsNvbs+U0X3WHDLlmyRNau/VmS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E53bgtiVHzRsxQ1rqUFYTpKjFmG+dr8SggUQ2ThsYbn9tZRQGpgsHQhy9+tK5H+N5wsY3FXojgAA
AABJRU5ErkJgguiPgeS8mOe9kQ==
)
D.
-
如图所示是测量电动机产生的力矩大小的简易装置.两个弹簧秤的上端固定在一个水平横杆上,下端连接着绕过粗糙圆板的皮带.电动机通过转轴可以带动粗糙圆板匀速转动,转动方向如图所示.
(1)圆板匀速转动时,______(填“左”或“右”)侧弹簧称读数较大;
(2)圆板匀速转动时,两弹簧秤读数分别为7N和3N,圆板半径r=0.2m,则电动机对圆板产生的力矩为______Nm.
(3)已知该电动机工作时对外产生的力矩大小与转速有关,转速越大,则对外力矩越小.在不改变该装置其他设备的情况下,换一粗糙程度相同的圆板,半径大于0.2m,转速稳定后弹簧秤读数相比原来不变,则此时圆板的转速相比原来应______(填“增大”、“减小”或“不变”).
-
如图a所示为测量电动机匀速转动时角速度的实验装置,半径不大的圆形卡纸固定在电动机转轴上,在电动机的带动下匀速转动,在圆形卡纸的一侧垂直安装一个改装了的电火花计时器,已知它可以每隔相同的时间T,在圆形卡纸上留下一个圆形斑点.某同学按下列实验步骤进行实验:
①使电火花计时器与圆形卡保持良好接触②启动电动机,使圆形卡纸转动起来③接通电火花计时器的电源,使其工作起来④关闭电动机,拆除电火花计时器;研究卡纸上留下的一段痕迹,如图b所示.写出角速度ω的表达式,代入数据,得出ω的测量值.
(1)要得到角速度ω的测量值,还缺少一种必要的测量工具,它是:________
A.秒表 B.毫米刻度尺 C.圆规 D.量角器
(2)若n个点对应的圆心角是θ,T为打点的时间间隔,写出ω的表达式ω=________ rad/s
(3)为了避免卡纸连续转动的过程中出现打点重叠,在电火花计时器与盘面保持良好接触的同时,可以缓慢地将电火花计时器沿圆形卡纸半径方向向卡纸中心移动.则卡纸上打下的点的分布曲线不是一个圆,而是类似一种螺旋线,如图c所示.这对测量结果有影响吗?________(填“有影响”或“没有影响”)
-
(8分)如图是电动打夯机的结构示意图,电动机带动质量为 m的重锤(重锤可视为质点)绕转轴0匀速转动,重锤转动半径为R.电动机连同打夯机底座的质量为M,重锤和转轴0之间连接杆的质量可以忽略不计,重力加速度为g.
(1)重锤转动的角速度为多大时,才能使打夯机底座刚好离开地面?
(2)若重锤以上述的角速度转动,当打夯机的重锤通过最低位置时,打夯机对地面的压力为多大?
![](https://img.xintiku.com/upload/89/7b/897b071aaa7b7f141779e20759177b7b.jpg)
-
如图是电动打夯机的结构示意图,电动机带动质量为 m的重锤(重锤可视为质点)绕转轴0匀速转动,重锤转动半径为R.电动机连同打夯机底座的质量为M,重锤和转轴0之间连接杆的质量可以忽略不计,重力加速度为g.
(1)重锤转动的角速度为多大时,才能使打夯机底座刚好离开地面?
(2)若重锤以上述的角速度转动,当打夯机的重锤通过最低位置时,打夯机对地面的压力为多大?
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如图是电动打夯机的结构示意图,电动机带动质量为 m的重锤(重锤可视为质点)绕转轴0匀速转动,重锤转动半径为R.电动机连同打夯机底座的质量为M,重锤和转轴0之间连接杆的质量可以忽略不计,重力加速度为g.
(1)重锤转动的角速度为多大时,才能使打夯机底座刚好离开地面?
(2)若重锤以上述的角速度转动,当打夯机的重锤通过最低位置时,打夯机对地面的压力为多大?
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如图是一种蛙式夯土机,电动机带动质量为m的重锤(重锤可视为质点)绕转轴O匀速转动,重锤转动半径为R.电动机连同夯土机底座的质量为M,重锤和转轴O之间连接杆的质量可以忽略不计,重力加速度为g。要使夯土机底座能离开地面,重锤转动的角速度至少为( )
![](https://img.xintiku.com/upload/d4/ca/d4caff84670c20e45381b12724559938.png)
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如图甲所示为测量电动机转动角速度的实验装置,半径不大的圆形卡纸固定在电动机转轴上,在电动机的带动下匀速转动.在圆形卡纸的旁边垂直安装一个改装了的电火花计时器.(电火花计时器每隔相同的时间间隔打一个点)
(1)请将下列实验步骤按先后排序:_________.
①使电火花计时器与圆形卡纸保持良好接触
②接通电火花计时器的电源,使它工作起来
③启动电动机,使圆形卡纸转动起来
④关闭电动机,拆除电火花计时器;研究卡纸上留下的一段点迹(如图乙所示),写出角速度ω的表达式,代入数据,得出ω的测量值.
(2)要得到角速度ω的测量值,还缺少一种必要的测量工具,它是_______
A.秒表 B.毫米刻度尺 C.圆规 D.量角器
(3)为了避免在卡纸连续转动的过程中出现打点重叠,在电火花计时器与盘面保持良好接触的同时,可以缓慢地将电火花计时器沿圆形卡纸半径方向向卡纸中心移动.则卡纸上打下的点的分布曲线不是一个圆,而是类似一种螺旋线,如图丙所示.这对测量结果_______(填“有”或“无”)影响.
![](https://img.xintiku.com/upload/e5/33/e533494751f1c20fafb71fffce673f0c.png)