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如图,两个质量均为m的小木块a和b(可视为质点)放在水平圆盘上,a与转轴OO'的距离为l ,b与转轴的距离为2l。木块与圆盘的最大静摩擦力为木块所受重力的k倍,重力加速度大小为g。若圆盘从静止...
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如图两个质量均为m的小木块a和b可视为质点放在水平圆盘上a与转轴OO′的距离为L.b与转轴的距离为2
b一定比a先开始滑动
a、b所受的摩擦力始终相等
ω=
是b开始滑动的临界角速度
当ω=
时,a所受摩擦力的大小为kmg
如图所示一质量为M.的楔形木块放在水平桌面上它的顶角为90°两底角为α和βab为两个位于斜面上质量均
如图所示质量M=2kg的一定长度的长木板静止在光滑水平面上在其左端放置一质量m=1kg的小木块可视为
滑出瞬间,小木块的速度为2 m/s
滑出瞬间,小木块的速度为4 m/s
滑出瞬间,长木板的速度为2 m/s
滑出瞬间,长木板的速度为4 m/s
如图8所示轮A和B可视为均质圆盘半径均为r质量均为m1绕在二轮上的绳索中间连有物块C设物块C的质量
质量为m0=20kg长为L=5m的木板放在水平面上木板与水平面间的动摩擦因数为μ1=0.15将质量m
木板一定静止不动,小木块不能滑出木板
木板一定静止不动,小木块能滑出木板
木板一定向右滑动,小木块不能滑出木板
木板一定向右滑动,小木块能滑出木板
如图所示小木块可视为质点质量m=2kg长木板长L=1.44m质量M=10kg木板与木块间的动摩擦因数
如图所示一质量为M.的楔形木块放在水平桌面上它的顶角为90°两底角为α和βab为两个位于斜面上质量均
Mg+mg
Mg+2mg
Mg+mg (sinα+sinβ)
Mg+mg (cosα+cosβ)
如图所示一质量为M.的楔形木块放在水平桌面上它的顶角为90°两底角为α和β
B.为两个位于斜面上质量均为m的小木块.已知所有接触面都是光滑的.现使A.
同时沿斜面下滑,则下列说法正确的是 A.楔形木块静止不动 B.楔形木块向左运动
A.木块处于失重状态
B.木块处于超重状态
8分如图13所示质量为M.的木板长为L.木板的两个端点分别为A.B.中点为O.木板置于光滑的水平面上
如图所示两块长度均为d=0.2m的木块A.B.紧靠着放在光滑水平面上其质量均为M.=0.9kg一颗质
如图所示一质量为M.倾角为θ的斜面体放在水平地面上质量为m的小木块可视为质点放在斜面上现施加一平行于
斜面体受到地面的最大摩擦力为Fsinθ
斜面体受到地面的最大摩擦力为Fcosθ
小木块受到斜面的最大摩擦力为
小木块受到斜面的最大摩擦力为F.+mgsinθ
如图所示一质量为M.的楔形木块放在粗糙水平桌面上它的顶角为90°两底角为α和βab为两个位于斜面上质
楔形木块对水平桌面的压力等于Mg+2mg
楔形木块对水平桌面的压力等于Mg+mg
地面对楔形木块有摩擦力的作用
地面对楔形木块无摩擦力的作用
如图所示一质量为M.倾角为θ的斜面体在水平地面上质量为m的小木块可视为质点放在斜面上现用一平行斜面大
小木块受到斜面的最大摩擦力为F.+mgsin θ
小木块受到斜面的最小摩擦力可能为零
斜面体受到地面的最大摩擦力为F.
斜面体受到地面的最小摩擦力为零
如图所示两个质量均为m的小木块a和b可视为质点放在水平圆盘上a与转轴OOʹ的距离为lb与转轴OOʹ
b一定比a先开始滑动
a.b所受的静摩擦力大小始终相等
当ω=
时,a所受摩擦力的大小为kmg
ω=
时b开始滑动
如图所示一个质量为M.的楔形木块放在水平桌面上它的顶角为90°两底角为α和β
b为两个位于斜面上质量均为m的小木块,已知所有接触面都是光滑的。现发现α.b沿斜面下滑,而楔形木块保持静止不动,则这时楔形木块对水平桌面的压力等于 ( ) A.Mg + 2mg
Mg + mg
Mg + mg(sinα + sinβ)
Mg + mg(cosα + cosβ)
如图所示一质量为M.倾角为θ的斜面体在水平地面上质量为m的小木块可视为质点放在斜面上现用一平行斜面大
小木块受到斜面的最大摩擦力为F.+mgsin θ
小木块受到斜面的最小摩擦力可能为零
斜面体受到地面的最大摩擦力为F.
斜面体受到地面的最小摩擦力为零
如图两质量均为m长度均为L的木板放置在光滑的水平桌面上木块1质量也为m可视为质点放于木板2的最右端木
如图3所示一个匀速转动的半径为r的水平圆盘上放着两个小木块M.和N.木块M.放在圆盘的边缘处木块N.
M.受到重力、支持力、向心力
M.、N.两木块的线速度相等
M.的角速度是N.的3倍
M.的向心加速度是N.的3倍
如图两个质量均为m的小木块AB用轻绳相连放在水平圆盘上A恰好处于圆盘中心B与转轴的距离为l.木块与
如图.两个小木块a质量为2m和b质量为m均可视为质点放在水平圆盘上a与转轴00'的距离为lb与转轴的
b一定比a先开始滑动
当
,a、b所受的摩擦力大小始终相等
是b开始滑动的临界角速度
当
时,a所受摩擦力的大小为2kmg/3
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下面短文中有10处语言错误请在有错误的地方增加删除或修改某个单词 注意 1.每句不超过两个错误 2.每处错误及修改均仅限一词 3.只允许修改10处多者从第11处起不计分 Helloboysandgirls!TodayIamgoingtotalkwithwhatyoushoulddowhenafirealarmgooff.Ifyouhearthealarmstandinlineatthedoorandwaityourteachertoleadyououtside.Stayclosetoyourteacherandclassmate.Don’tpanicorgetoutoflineandtryingtoremainquietandcalmly.Soonthefirefighterswillcomeandputoutafire.Ifit’safalsealarmandthereisnofireyourteacherwillleadusbacktotheclassroom.Ifyounoticethatwhensomeoneismissingandhurttellyourteacherimmediately.
下面短文中有10处语言错误请在有错误的地方增加删除或修改某个单词 注意 1.每句不超过两个错误 2.每处错误及修改均仅限一词 3.只允许修改10处多者从第11处起不计分 Helloboysandgirls!TodayIamgoingtotalkwithwhatyoushoulddowhenafirealarmgooff.Ifyouhearthealarmstandinlineatthedoorandwaityourteachertoleadyououtside.Stayclosetoyourteacherandclassmate.Don’tpanicorgetoutoflineandtryingtoremainquietandcalmly.Soonthefirefighterswillcomeandputoutafire.Ifit’safalsealarmandthereisnofireyourteacherwillleadusbacktotheclassroom.Ifyounoticethatwhensomeoneismissingandhurttellyourteacherimmediately.
图2为某个组团式城市布局图各城区分散布局完成3~4题 该城市规划建设物流园区和化工园区应分别安排在
下面短文中有10处语言错误请在有错误的地方增加删除或修改某个单词 注意 1.每句不超过两个错误 2.每处错误及修改均仅限一词 3.只允许修改10处多者从第11处起不计分 Helloboysandgirls!TodayIamgoingtotalkwithwhatyoushoulddowhenafirealarmgooff.Ifyouhearthealarmstandinlineatthedoorandwaityourteachertoleadyououtside.Stayclosetoyourteacherandclassmate.Don’tpanicorgetoutoflineandtryingtoremainquietandcalmly.Soonthefirefighterswillcomeandputoutafire.Ifit’safalsealarmandthereisnofireyourteacherwillleadusbacktotheclassroom.Ifyounoticethatwhensomeoneismissingandhurttellyourteacherimmediately.
下面短文中有10处语言错误请在有错误的地方增加删除或修改某个单词 注意 1.每句不超过两个错误 2.每处错误及修改均仅限一词 3.只允许修改10处多者从第11处起不计分 Helloboysandgirls!TodayIamgoingtotalkwithwhatyoushoulddowhenafirealarmgooff.Ifyouhearthealarmstandinlineatthedoorandwaityourteachertoleadyououtside.Stayclosetoyourteacherandclassmate.Don’tpanicorgetoutoflineandtryingtoremainquietandcalmly.Soonthefirefighterswillcomeandputoutafire.Ifit’safalsealarmandthereisnofireyourteacherwillleadusbacktotheclassroom.Ifyounoticethatwhensomeoneismissingandhurttellyourteacherimmediately.
图4为甲地所在区域某时刻高空两个等压面P1和P2的空间分布示意图图中甲乙两地经度相同完成8~10题 若该日甲乙两地同时日出则甲地该日
阅读下面短文并用英语回答问题请注意题后的词数要求 Whenmyfatherwascelebratingamilestone里程碑birthdayIpulledtogetherasurprisegifttreathewouldneverforget. Ashewasapproaching60Ihadafunidea:WhatifIcouldgetthememoriespeoplehadofhimputeachoneintoanenvelope—60intotal—andhavehimopenthemonebyoneonhisbirthdaySoIwroteane-mailtofamilyandfriendsexplainingmyidea. Isentthee-mailandwaited.AndthentherepliesstartedcominginandIwasveryverysurprised.Thereweresomanymemoriesandtheywereallsolovely.Theycamefromthe’50s’60s’70sfromeverydecade十年betweennowandthedaymydadwasborn.Theycamefrommymothermysiblingsmygrandmamydad’sfriendsfromhighschoolhissistermydad’sfirstbossacolleagueathisfirstjobfrompeoplewhohadn’tseenmydadin40yearsfrompeopleImyselfhadn’teveninformed.Theytypedthemandhandwrotethem.Theymailedthemande-mailedthem. ThenightbeforeDad’sbirthdaymysisterandIstayeduplateputtingeverythingtogetherwithsomeenvelopes. Thenextmorningafterbreakfastandpresentsandcakewegavethepileofenvelopestohim.Justonemorethingforyouwesaid. Ittookhimalongtimetoopenthemandread.Eachonewasabrieftickettoanothertimealeap跳跃backwardoveryearsanddecades.Therewasalotoflaughterandafewtearstoo. Iwaskindofsadwhentheprojectwasoverbecauseitwasgreatfuntocollectthesememories.Itgavemeadifferentpictureofdad. Whendidtheauthorgiveherfatherasurprisegiftnomorethan4words
E Womenarefriendly.ButmenaremorecompetitiveWhyResearchershavefoundit’salldowntothehormoneoxytocin荷尔蒙催生素.Althoughknownasthelovehormoneitaffectsthesexesdifferently. Womentendtobesocialintheirbehavior.TheyoftensharewithothersButmentendtobecompetitiveTheyaretryingtoimprovetheirsocialstatussaidProfessorRyan. Generallypeoplebelievethatthehormoneexytocinisletoutinourbodyinvarioussocialsituationsandourbodycreatesalargeamountofitduringpositivesocialinteraction互动suchasfallinginloveorgivingbirth. ButinapreviousexperimentProfessorRyanfoundthatthehormoneisalsoletoutinourbodyduringnegativesocialinteractionssuchasenvy. Furtherresearchesshowedthatinmenthehormoneoxytocinimprovestheabilitytorecognizecompetitiverelationshipsbutinwomenitraisestheabilitytorecognizefriendship. ProfessorRyan’srecentexperimentused62menandwomenaged20to37. Halfoftheparticipants参与者receivedoxytocin.Theotherhalfreceivedplacebo安慰剂. Afteraweekthetwogroupsswitchedwithparticipants.Theywentthroughthesameprocedurewiththeothermaterial. Followingeachtreatmenttheywereshownsomevideopictureswithdifferentsocialinteractions.Thentheywereaskedtoanalyzetherelationshipsbyansweringsomequestions.Thequestionswereabouttellingfriendshipfromcompetition.Andtheiranswersshouldbebasedongesturesbodylanguageandfacialexpressions. Theresultsindicatedthataftertreatmentwithoxytocinmen’sabilitytocorrectlyrecognizecompetitiverelationshipsimprovedbutinwomenitwastheabilitytocorrectlyrecognizefriendshipthatgotbetter. ProfessorRyanthusconcluded:Ourexperimentprovesthatthehormoneoxytocincanraisepeople’sabilitiestobetterdistinguishdifferentsocialinteractions.Andthebehaviordifferencesbetweenmenandwomenarecausedbybiologicalfactor因素thataremainlyhormonal. Whatcausesmenandwomentobehavedifferentlyaccordingtothetext
图3为我国某区域冬季某日8时至次日8时的降雪量和积雪深度分布图该时段该区域风向主要为偏东风云量分布差异不明显完成5~7题 图中M地积雪深度低于周围地区该地可能是
下面短文中有10处语言错误请在有错误的地方增加删除或修改某个单词 注意 1.每句不超过两个错误 2.每处错误及修改均仅限一词 3.只允许修改10处多者从第11处起不计分 Helloboysandgirls!TodayIamgoingtotalkwithwhatyoushoulddowhenafirealarmgooff.Ifyouhearthealarmstandinlineatthedoorandwaityourteachertoleadyououtside.Stayclosetoyourteacherandclassmate.Don’tpanicorgetoutoflineandtryingtoremainquietandcalmly.Soonthefirefighterswillcomeandputoutafire.Ifit’safalsealarmandthereisnofireyourteacherwillleadusbacktotheclassroom.Ifyounoticethatwhensomeoneismissingandhurttellyourteacherimmediately.
阅读下面短文并用英语回答问题请注意题后的词数要求 Whenmyfatherwascelebratingamilestone里程碑birthdayIpulledtogetherasurprisegifttreathewouldneverforget. Ashewasapproaching60Ihadafunidea:WhatifIcouldgetthememoriespeoplehadofhimputeachoneintoanenvelope—60intotal—andhavehimopenthemonebyoneonhisbirthdaySoIwroteane-mailtofamilyandfriendsexplainingmyidea. Isentthee-mailandwaited.AndthentherepliesstartedcominginandIwasveryverysurprised.Thereweresomanymemoriesandtheywereallsolovely.Theycamefromthe’50s’60s’70sfromeverydecade十年betweennowandthedaymydadwasborn.Theycamefrommymothermysiblingsmygrandmamydad’sfriendsfromhighschoolhissistermydad’sfirstbossacolleagueathisfirstjobfrompeoplewhohadn’tseenmydadin40yearsfrompeopleImyselfhadn’teveninformed.Theytypedthemandhandwrotethem.Theymailedthemande-mailedthem. ThenightbeforeDad’sbirthdaymysisterandIstayeduplateputtingeverythingtogetherwithsomeenvelopes. Thenextmorningafterbreakfastandpresentsandcakewegavethepileofenvelopestohim.Justonemorethingforyouwesaid. Ittookhimalongtimetoopenthemandread.Eachonewasabrieftickettoanothertimealeap跳跃backwardoveryearsanddecades.Therewasalotoflaughterandafewtearstoo. Iwaskindofsadwhentheprojectwasoverbecauseitwasgreatfuntocollectthesememories.Itgavemeadifferentpictureofdad. Whatwasthesurprisegiftnomorethan6words
E Womenarefriendly.ButmenaremorecompetitiveWhyResearchershavefoundit’salldowntothehormoneoxytocin荷尔蒙催生素.Althoughknownasthelovehormoneitaffectsthesexesdifferently. Womentendtobesocialintheirbehavior.TheyoftensharewithothersButmentendtobecompetitiveTheyaretryingtoimprovetheirsocialstatussaidProfessorRyan. Generallypeoplebelievethatthehormoneexytocinisletoutinourbodyinvarioussocialsituationsandourbodycreatesalargeamountofitduringpositivesocialinteraction互动suchasfallinginloveorgivingbirth. ButinapreviousexperimentProfessorRyanfoundthatthehormoneisalsoletoutinourbodyduringnegativesocialinteractionssuchasenvy. Furtherresearchesshowedthatinmenthehormoneoxytocinimprovestheabilitytorecognizecompetitiverelationshipsbutinwomenitraisestheabilitytorecognizefriendship. ProfessorRyan’srecentexperimentused62menandwomenaged20to37. Halfoftheparticipants参与者receivedoxytocin.Theotherhalfreceivedplacebo安慰剂. Afteraweekthetwogroupsswitchedwithparticipants.Theywentthroughthesameprocedurewiththeothermaterial. Followingeachtreatmenttheywereshownsomevideopictureswithdifferentsocialinteractions.Thentheywereaskedtoanalyzetherelationshipsbyansweringsomequestions.Thequestionswereabouttellingfriendshipfromcompetition.Andtheiranswersshouldbebasedongesturesbodylanguageandfacialexpressions. Theresultsindicatedthataftertreatmentwithoxytocinmen’sabilitytocorrectlyrecognizecompetitiverelationshipsimprovedbutinwomenitwastheabilitytocorrectlyrecognizefriendshipthatgotbetter. ProfessorRyanthusconcluded:Ourexperimentprovesthatthehormoneoxytocincanraisepeople’sabilitiestobetterdistinguishdifferentsocialinteractions.Andthebehaviordifferencesbetweenmenandwomenarecausedbybiologicalfactor因素thataremainlyhormonal. WhydidProfessorRyanconducttherecentexperiment
图4为甲地所在区域某时刻高空两个等压面P1和P2的空间分布示意图图中甲乙两地经度相同完成8~10题 此时甲地近地面的风向为
阅读下面短文并用英语回答问题请注意题后的词数要求 Whenmyfatherwascelebratingamilestone里程碑birthdayIpulledtogetherasurprisegifttreathewouldneverforget. Ashewasapproaching60Ihadafunidea:WhatifIcouldgetthememoriespeoplehadofhimputeachoneintoanenvelope—60intotal—andhavehimopenthemonebyoneonhisbirthdaySoIwroteane-mailtofamilyandfriendsexplainingmyidea. Isentthee-mailandwaited.AndthentherepliesstartedcominginandIwasveryverysurprised.Thereweresomanymemoriesandtheywereallsolovely.Theycamefromthe’50s’60s’70sfromeverydecade十年betweennowandthedaymydadwasborn.Theycamefrommymothermysiblingsmygrandmamydad’sfriendsfromhighschoolhissistermydad’sfirstbossacolleagueathisfirstjobfrompeoplewhohadn’tseenmydadin40yearsfrompeopleImyselfhadn’teveninformed.Theytypedthemandhandwrotethem.Theymailedthemande-mailedthem. ThenightbeforeDad’sbirthdaymysisterandIstayeduplateputtingeverythingtogetherwithsomeenvelopes. Thenextmorningafterbreakfastandpresentsandcakewegavethepileofenvelopestohim.Justonemorethingforyouwesaid. Ittookhimalongtimetoopenthemandread.Eachonewasabrieftickettoanothertimealeap跳跃backwardoveryearsanddecades.Therewasalotoflaughterandafewtearstoo. Iwaskindofsadwhentheprojectwasoverbecauseitwasgreatfuntocollectthesememories.Itgavemeadifferentpictureofdad. Whydidtheauthorandhersisterstayuplatethenightbeforetheirfather’sbirthdaynomorethan9words
改革开放后随着我国社会经济的发展人口迁移日趋频繁完成1~2题 下列对当前人口迁出主要流向的表述与实际最相符的是
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