问题 计算题

武平梁野山素有天然氧吧之称,其险峻的高山、飞流的瀑布令人叹为观止。依瀑流而建的木栈道蜿蜒至山脚,长约4km,高度差约90m,方便了人们近距离感受瀑布的磅礴气势。体重50kg的小王从栈道最高处小跑至山脚,用时30min,求这段时间小王自身重力做的功及功率约为多少?(g取10N/kg)

答案

解:小王自身重力做的功W=Gh ;

做功的功率为

功的计算离不开重力和下降的高度,这两个物理量都已知,故功可直接计算得出;而功率用功除时间即可,注意时间的单位是min,要将其化成秒。

完形填空
Martin is a fifteen-year-old boy. He used to be a “problem child”, but a recent communication with his mother changed his life. In the past, He didn’t give his mother many problems.        , after his father’s death a few years ago, Martin’s life became      more difficult. His mother couldn’t afford to pay for her child’s education. To do this, she     work, and so was often not at home. 
His mother looked after him as       as she could. Unluckily, Martin still caused problems. He was not        studying and he often got into trouble. Luckily, his mother was very       and didn’t give up trying to help him. In the end, she       a difficult decision: to send him to a boys’  boarding(寄宿) school. Martin hated it and used to cause a lot of trouble.
One day, he told his teacher he wanted to leave the school. The teacher said      was necessary for Martin to talk with his mother. Martin called his mother, but to his        ,this phone call changed his life. “It was exactly what I needed,” he said. “My mother helped me to understand how much she had given me.
Now Martin has        changed. He has been working hard and is now one of the best students in his class. How was he able to change? His mother’s love helped him to feel good about himself.
小题1:
A.SoB.OtherwiseC.ThereforeD.However
小题2:
A.veryB.manyC.muchD.too
小题3:
A.couldB.had toC.shouldD.would
小题4:
A.soonB.quicklyC.wellD.good
小题5:
A.angry withB.tired ofC.crazy aboutD.interested in
小题6:
A.worriedB.patientC.carefulD.serious
小题7:
A.madeB.tookC.gotD.thought
小题8:
A.thatB.thisC.heD.it
小题9:
A.surprisedB.surprising C.surpriseD.surprises
小题10:
A.alwaysB.hardlyC.reallyD.just
填空题