问题 实验题

测木块与长木板之间的动摩擦因数时,采用如图所示的装置,图中长木板水平固定。

(1)实验过程中,电火花计时器应接在_____(选填“直流”或“交流”)电源上。调整定滑轮高度,使细线与长木板平行。

(2)已知重力加速度为g,测得木块的质量为M,砝码盘和砝码的总质量为m,木块的加速度为a,则木块与长木板间的动摩擦因数μ=________。

(3)如下图所示,为木块在水平木板上带动纸带运动打出的一条纸带的一部分,0、1、2、3、4、5、6为计数点,相邻两计数点间还有4个打点未画出。从纸带上测出x1=3.20 cm,x2=4.52 cm,x5=8.42 cm,x6=9.70 cm。则木块加速度大小a=_____ m/s2(保留两位有效数字)。

答案

(1)交流 (2)  (3)1.3

题目分析:(1)实验过程中,电火花计时器应接在交流电源上.。

(2)根据牛顿定律,对砝码盘和砝码,对小车,联立解得

(3)根据匀变速运动的规律得,,则

阅读理解

TheUnitedStateshasaround475,000schoolbuses.Eachdaytheycarrymorethan25million children,halfofalltheschoolchildreninthecountry.

Thesebuses,onaverage,use4litersofdiesel(柴油)fueltotravellessthan16kilometers. When theschoolyearbeganlastfall,dieselaveraged55centsaliternationally.Thepricenearlydoubledby theendofschool inJune.

BobRileyisthespokesmanfortheAmericanSchoolBusCouncil.Hesaysfuelpricesnegotiated(商议) for schools arenot lower thanothers have to pay. Asaresult,schoolsarelookingfor waystoreducetransportationcosts.Busroutesarebeing redrawnor,insomecases,canceled.Someareas arebuyingbusesthatuse naturalgas orother alternativefuels.

Otherstepsincludefewerfieldtrips andlesstravel bysports teams.Someschool districtsmayend any busservicenotrequiredby law.

Studiesshowthatschoolbusesarethesafestform oftransportationtoandfrom school.

The AmericanSchoolBus Councilsayscutsinbus serviceare badfor childrenandpossiblythe environment.Itsaysremovingbusesfromtheroadwillmeananincreaseinothervehiclestransporting students. Spokesman Bob Riley saysanotherconcern is thatreducing  busservicemightreduce attendance.

It couldalso getmorechildren to walkor bicycle to school.That wouldsurely makepeople happy attheNationalCenterforSafeRoutestoSchool.Morekidswalkingorbikingsafelytoschoolisthe aimofa3-year-oldfederal program,partofaninternationalmovement.Thegoalis toincreasephysical activity and reduce air pollution.

小题1:Inthesecondparagraph,theauthorwantsto provethat   .

A.toomany schoolchildren takebuses every day

B.thecost offuelhasincreased

C.theschoolbusesconsumemorefuelthanaverage

D.the school busesusuallygoon long routes小题2:Inthe thirdparagraph,what doesBobRiley mean'?

A.Thefuel pricesforschool busesneed to be negotiated again.

B.High fuelprices are also affecting the efficiency of their services.

C.The fuelprices for school are much higher thanothers pay.

D.TheAmericanSchool BusCouncilshould workforstudents’benefit.小题3:Whatistheadvantage ofreducingschoolbusserviceaccordingto thepassage?

A.Morefuelwillbesaved.

B.Studentscangotoschool inasaferway.

C.Studentscanexercisebywalkingorriding toschool.

D.Trafficjams willbereducedduringrushhour.小题4:Whatisthesixth paragraphmainly about?

A.Bob Riley's concern about the resultsof reducing school buses.

B.Theconvenience brought by school buses.

C.Thebad effectsofreducingschool buses.

D.Thestudiesabout students'choicescarried out by theAmericanSchool BusCouncil.

单项选择题 A1型题