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小代用如图所示的滑轮组将重为640N的物体匀速提升了2m，用时40s，此过程中滑轮组机械效率为80%，不考虑绳重及摩擦，则绳端的拉力是 N，拉力的功率是 W．
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用如图所示滑轮组提升重物.人用50N的拉力F.10s内使重为90N的物体匀速上升了3m.不计绳中和摩
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用如图所示的滑轮组将重为500N的物体在2s内匀速提升6m已知拉力F.的大小为200N求1滑轮组提升
如图所示用滑轮组将重为600N的重物匀速提升如果拉力为350N则下列结论中正确的是:
如果将物理提升2m，拉力做功1200J;
物体升高1m，机械所做的有用功为350J;
物体以0.5m/s速度匀速上升，拉力的功率为350W;
此滑轮组的机械效率为80%.
2.00分小代用如图所示的滑轮组将重为640N的物体勾速提升了2m用时40s此过程中滑轮组机械效率
如图所示用两个定滑轮和一个动滑轮组成滑轮组每个滑轮重为30N.用这个滑轮组把重300N的物体匀速提升
如图所示小明用一个滑轮组匀速提升重为200N的物体物体在4s内上升2m的过程中人所用的拉力为125N
纹川地震过后灾区人们在全国人民的帮助下正在重建家园如图所示在灾区的一个建筑工地上建筑工人用滑轮组来提
利用如图所示的滑轮组提升重物不计摩擦和绳子的重力现用500N的拉力F.将重为1800N的物体在5s内
如图所示用滑轮组匀速提升重为700N的物体人对绳的拉力F.为400N在10s内把物体匀速提升了2m不
拉力的功率是80W
拉力所做的总功是1400J
拉力所做的额外功是200J
滑轮组的机械效率是58.3%
用如图所示的滑轮组将重为12N的物体匀速提升5m拉力F.=5N求滑轮组的机械效率为多少若将物体全部浸
如图所示用滑轮组匀速提起一个重为400N的物体物体在5s内竖直上升了2m人拉绳的力为250N不计绳重
小代用如图所示的滑轮组将重为640N的物体匀速提升了2m用时40s此过程中滑轮组机械效率为80%不
用如图所示的滑轮组将重为500N的物体在2s内匀速提升6m已知拉力F.的大小为200N求1滑轮组提升
如图所示用两个定滑轮和一个动滑轮组成滑轮组每个滑轮重为30N.用这个滑轮组把重300N的物体匀速提升
用如图所示滑轮组提升重物.人用50N的拉力F.10s内使重为90N的物体匀速上升了3m.不计绳中和摩
用如图所示滑轮组将重为300N的物体匀速提高2m人对绳的拉力为175N不计绳重和摩擦拉力所做的功是J
利用如图所示的滑轮组在20s时间内将重为20N的物体匀速提升了2m所用拉力F.为12.5N下列判断正
绳子自由端移动的速度为0.1m/s
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此段时间内，拉力做功为40J
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用如图所示的滑轮组将重为500N的物体在2s内匀速提升6m已知拉力F.的大小为200N求1滑轮组提升
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TheMetropolitanMuseumofArtMetisoneoftheworld'slargestandfinestartmuseums.Followingthesuggestedroutewillhelpyouexplorethemuseum.TheTempleofDendurThis2000﹣year﹣oldbuildingstoodneartheNileRiversurroundedbyawallthatnolongerexists.Butyoucanstillpeekthroughthegateway.Whose'house'isthis?It'snotforpeople.It'sforgods.Canyouidentifythem?Theyfaceout.Akingfacesinbringingofferings.MetSpeaksBringingtogethersomeofthemostrespectedthinkersonagivensubjectMetSpeaksfeatureslecturesdiscussionstalksfilmsandforumsinwhichcompellingvoicesexploretimelyissuesthatconnecttotheMet'sexhibitionsandpermanentcollection.Programtimesaudiencesandtopicsvary.TimetoSketchSettledownforafewminutespicksomethinginthisgalleryandhavefundrawingit.Enjoythechancetolookcarefullyasyoucreateyourownsketch.You'llbesurprisedathowmuchmoreyounoticethankstoexploringartbysketching.MetAccessMaketheMetyours!Choosefromavarietyofservicesandexcitingprogramsthataretailoredtomeettheneedsofvisitorswithdisabilities.Programtimesaudiencesandtopicsvary.AskfortheAccessInformationbrochureandAccessCalendaratInformationDesksdownloadtheAccessCalendarPDForcall212﹣650﹣2010oremailaccess@metmuseum.org.AdmissionFeeincludesadmissiontotheMainBuildingandsame﹣weekadmissiontotheCloistersmuseumandgardens.1Howmuchisrecommendedtopayfor3adultand2studentvisitors?A.﹩99B.﹩111C.﹩87D.﹩1032WhatcanyouknowabouttheTempleofDendur?A.Ahighwallissurroundingthe2000﹣year﹣oldbuildingnow.B.Akingfacesoutbringingofferingsinthetemple.C.ThebuildingisdesignedforEmperortolivein.D.TheNileRiverwitnessedthehistoryofthebuilding.3WhichofthefollowingisTRUEabouttheMet?A.IssuesconnectedwitheconomiccrisiswillbediscussedinMetSpeaks.B.Visitorscanchoosesomethinginthegalleryandhavefundrawingitonthewall.C.Disabledpeoplewillfindvariousservicesandprogramsofferedespeciallyforthem.D.Youcanemailaccess@metmuseum.orgformoreAdmissioninformation.
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