初中物理探究杠杆的平衡条件实验试题

如图所示，杠杆处于平衡状态，则F的力臂是
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               

A．OA

B．OC

C．OD

D．FD

如图所示，杠杆在力F1、F2作用下处于平衡状态，L1为F1的力臂。请在图中作出F2的力臂L2及力F1。

如图所示，起瓶器开启瓶盖时，可看作是

A．以B为支点的费力杠杆	B．以B为支点的省力杠杆
C．以A为支点的费力杠杆	D．以A为支点的省力杠杆

各式各样的剪刀都是杠杆．如图所示，要剪开铁皮，应该用       最合适；剪纸或布时，应该用       最合适．(选填标号) 

“给我一个支点和一根足够长的棍，我就能撬起整个地球．”下列生产和生活中的杠杆与阿基米德设想的杠杆属于同一类型的是

如图所示的杠杆B点挂着重物G，若在A点施加一个最小的力F使杠杆平衡在图中的位置.请在图中画出此力的示意图和力臂.
                  

人体就像一部复杂的机器，包含许多物理知识。

(1)人体是______体(导／半导／绝缘)，人体的安全电压_____________V；
(2)人的前臂如图甲所示，是一个________(省力／费力／等臂)杠杆，这个杠杆的好处是_____________；
(3)正常人的心脏推动血液流动的功率约为1.5W，那么在3s内心脏做的功是__________J，这些功可把一个0.5N的鸡蛋匀速举高____________m.

如图所示，是一种指甲刀的结构示意图，下列说法正确的是(    )

A．ABC是一个省力杠杆

B．D处刀刃较薄，可以增大压力

C．杠杆ABC上有粗糙的花纹，可以减小摩擦

D．指甲刀只有两个杠杆，一个省力杠杆，一个费力杠杆

如图所示，在课桌的C点用最小的力把桌腿B抬离地面，在抬起时桌腿A 没有滑动，请在C点画出这个力的示意图，并标出它的力臂l。

日本丰田汽车公司，因汽车脚垫和油门踏板问题引发了召回事件，其中油门踏板是一种  _  __  类(填“杠杆”或“斜面”)简单机械。当司机踩下油门时，这台四冲程的汽油机每秒做功_  __  次（RPM（Revolutions Per Minute）：每分钟转数）
 

如图所示，秤砣的质量为100 g，秤杆的质量忽略不计。秤杆水平静止时，OA=5cm，OB="25" cm，则被测物的质量为  kg。若秤砣有缺损时，则杆秤所示的质量值  被测物的真实质量值(选填“小于”、“等于”或“大于”)。

如图所示的用具中，属于省力杠杆的是(　 　)

探究杠杆的平衡条件：
（1）如图（a），杠杆在支架上，要使其在水平位置平衡，可以将杠杆左端的平衡螺母向      调节，当杠杆在水平位置平衡时，杠杆自重的力臂为       cm．

（2）如图（b），在右边用弹簧测力计沿着竖直向下拉，使杠杆在水平位置平衡，这样做的好处是      ．若左边钩码离支点20cm，右边挂钩离支点15cm，每个钩码重为0.5N，则此时弹簧测力计示数应为      N．
（3）如图（c），当杠杆在水平位置平衡时，与图（b）相比，弹簧测力计示数将      （选填“变大”、“变小”或“不变”）．

如图所示，用食指顶起一把金属勺子保持水平平衡状态，OA段和OB段的重分别为G₁和G₂．则下列判断正确的是（  ）

A．G1＞G2

B．G1＜G2

C．G1＝G2

D．无法判断

如图所示，是开瓶扳手开启瓶盖时的示意图，要将瓶盖打开，则在A处所用力的方向合理的是（  ）

A．竖直向上

B．竖直向下

C．水平向左

D．水平向右