问题 实验题

如图所示为测量倾斜气垫导轨上滑块加速度的实验,A、B为气垫导轨上的两个光电门,当滑块从气垫导轨一端匀加速滑下,滑块上的挡光片通过光电门时,可通过连接在光电门上的电子仪器记录时间。

(1)若用一螺旋测微器测量挡光片的宽度,如右图所示,读数为d =____   __cm;

(2)若某次测得挡光片通过光电门A的时间为t1,从A到B的时间为t,挡光片通过光电门B的时间为t2,利用所测得的物理量来表达滑块加速度,则其表达式为a =            。(用题设中各物理量符号表示)

答案

(1)0.6724~0.6727 (2) 

题目分析::(1)螺旋测微器的固定刻度读数为6.5mm.可动刻度读数为0.01×22.4mm=0.224mm,所以最终读数为:6.724mm=0.6724cm;

(2)由于遮光条通过光电门的时间极短,可以用平均速度表示瞬时速度.

滑块经过光电门A时的瞬时速度的表达式

滑块经过光电门B时的瞬时速度的表达式

根据匀变速直线运动速度时间公式得:

完形填空
A person’s home is as much a reflection of his personality as the clothes he wears, the food he eats and the friends with whom he spends his time. Depending on personality, most have in mind a(n) “______ home”. But in general, and especially for the student or new wage earners, there are practical ______ of cash and location on achieving that idea.
Cash ______, in fact, often means that the only way of ______ when you leave school is to stay at home for a while until things ______ financially. There are obvious ______of living at home—personal laundry is usually ______ done along with the family wash; meals are provided and there will be a well-established circle of friends to ______. And there is ______ the responsibility for paying bills, rates, etc.
On the other hand, ______ depends on how a family gets on. Do your parents like your friends? You may love your family—______do you like them? Are you prepared to be ______ when your parents ask where you are going in the evening and what time you expect to be back? If you find that you cannot strike a(n) ______, and that you finally have the money to leave, how do you ______ finding somewhere else to live?
If you plan to stay in your home area, the possibilities are ______well-known to you already. Friends and the local paper are always ______. If you are going to work in a ______ area, again there are the papers—and the accommodation agencies, ______ these should be approached with ______. Agencies are allowed to charge a fee, usually the ______ of the first week’s rent, if you take accommodation they have found for you.
小题1:
A.idealB.perfectC.imaginativeD.satisfactory
小题2:
A.demeritsB.weaknessesC.insufficienciesD.restrictions
小题3:
A.cutB.shortC.lackingD.drain
小题4:
A.getting withB.getting along withC.getting byD.getting back
小题5:
A.improveB.proceedC.developD.enhance
小题6:
A.concernsB.issuesC.problemsD.merits
小题7:
A.stillB.alwaysC.habituallyD.consequently
小题8:
A.call throughB.call overC.call onD.call out
小题9:
A.scarcelyB.lessC.littleD.sometimes
小题10:
A.littleB.muchC.adequateD.enough
小题11:
A.neverthelessB.whileC.howeverD.or
小题12:
A.moderateB.hostileC.indifferentD.lenient
小题13:
A.agreementB.consensusC.compromiseD.deal
小题14:
A.continueB.commenceC.commendD.confirm
小题15:
A.seldomB.lessC.absolutelyD.likely
小题16:
A.availableB.anaccessto informationC.valuableD.accessible
小题17:
A.time-honoredB.similarC.humidD.conversant
小题18:
A.thoughB.whileC.sinceD.as
小题19:
A.passionB.prudenceC.carelessnessD.concern
小题20:
A.sameB.equivalentC.equalD.similarity
多项选择题