问题 问答题

某种型号的飞机以60m/s的速度着陆,着陆后飞机的运动可看做匀减速直线运动,加速度大小6m/s2,问:

(1)着陆5s后飞机的速度为多少?着陆12s后飞机的速度为多少?

(2)问着陆后12s末汽车离开着陆点有多远?

答案

(1)由题意知飞机初速度为:v0=60m/s,加速度为:a=-6m/s2

根据速度时间关系有飞机5s后的速度为:v5=v0+at=60+(-6)×5m/s=30m/s

根据速度时间关系有飞机12s后的速度为:v12=v0+at=60+(-6)×12m/s=-12m/s,负号表示速度已反向,而飞机着陆后做匀减速运动不会减速运动,故12s后飞机已停止运动,故其速度为0

(2)由(1)判断12s末飞机已停止运动,所以飞机离着陆点距离即为飞机匀减速运动的位移,根据速度位移关系有:x=

v2-
v20
2a
=
0-602
2×(-6)
m=300m

答:(1)着陆5s后飞机的速度为30m/s,着陆12s后飞机的速度为0;

(2)问着陆后12s末汽车离开着陆点有300m远.

完形填空
Rudi Matt lived in a small village in the Swiss Alps in 1865. What he wanted most in the world was to climb   31  highest peak (山峰) in the Alps.   32  mother and his uncle, Franz, a mountain guide, wanted him to stop   33  and start working in a hotel. Rudi would not  34  his dream and secretly got in touch with an English mountain climber   35 was planning to climb the highest peak.
Franz was very angry when he found out   36  Rudi had done, but he finally agreed to let Rudi go if he went climbing, too. Franz also didn’t want to see Emil Saxo, a guide from another village, got to the top   37   him.
Rudi turned out to be a very good climber,  38   as they got close to the top, the Englishman got sick and couldn’t go on farther. Franz   39  behind to take care of him, but Saxo continued, wishing to be the   40  to the top. Rudi went after Saxo, hoping to   41  him to the top. When they met, Saxo fought with Rudi and fell down by accident. Saxo was   42  and hurt. Rudi must decide whether to carry Saxo back down to safety or to continue alone to the top.
He thought Saxo’s life was more   43  than his dream and helped him down. During that time, the Englishman and Franz continued the climb, and finally   44 reached the top. Later, the villagers   45  knew Rudi was the real conqueror (征服者) of the mountain.
小题1:
A.theB.aC.anD./
小题2:
A.RudiB.The Rudi’sC.Rudis’D.Rudi’s
小题3:
A.climbingB.climbC.to climbD.climbed
小题4:
A.try outB.give upC.go overD.work out
小题5:
A.whatB.whichC.whomD.who
小题6:
A.whichB.whatC.thatD.where
小题7:
A.afterB.behindC.beforeD.over
小题8:
A.butB.soC.orD.for
小题9:
A.walkedB.restedC.stayedD.watched
小题10:
A.firstB.secondC.thirdD.last
小题11:
A.takeB.beatC.pushD.help
小题12:
A.helpfulB.helpingC.helpsD.helpless
小题13:
A.popularB.successfulC.importantD.interesting
小题14:
A.heB.theyC.themD.him
小题15:
A.bothB.noneC.eitherD.all
单项选择题