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  • 英語翻譯

    英語翻譯
    1.Can the speed of an object change if the net work done on it is zero?
    2.Discuss whether any work is being done by each of the following agents and,if so,whether the work is positive or negative.
    a.a chicken scratching the ground
    b.a person reading a sign
    c.a crane lifting a bucket of concrete
    d.the force of gravity on the bucket in (c)
    3.Furniture movers wish to load a truck using a ramp from the ground to the rear of the truck.One of the movers claims that less work would be required if the ramp’s length were increased,reducing its angle with the horizontal.Is this claim valid?Explain.
    4.A pendulum swings back and forth,as shown at right.Does the tension force in the string do work on the pendulum bob?Does the force of gravity do work on the bob?Explainyour answers.
    5.The drivers of two identical cars heading toward each other apply the brakes at the same instant.The skid marks of one of the cars are twice as long as the skid marks of the other vehicle.Assuming that the brakes of both cars apply the same force,what conclusions can you draw about the motion of the cars?
    6.When a punter kicks a football,is he doing work on the ball while his toe is in contact with it?Is he
    doing work on the ball after the ball loses contact with his toe?Are any forces doing work on the ball
    while the ball is in flight
    7.A person lifts a 4.5 kg cement block a vertical distance of 1.2 m and then carries the block horizontally a distance of 7.3 m.Determine the work done by the person and by the force of gravity in this process.
    8.A plane designed for vertical takeoff has a mass of 8.0 × 103 kg.Find the net work done by all forces on the plane as it accelerates upward at 1.0 m/s2 through a distance of 30.0 m after starting from rest.
    英語人氣:854 ℃時(shí)間:2020-01-25 20:04:47
    優(yōu)質(zhì)解答
    1、一個(gè)物體,當(dāng)它所受到的各種力的功為0時(shí),它的速度是否會(huì)改變?2、下面各種情況中,介質(zhì)是否做功?如果做功,那么此功為正還是為負(fù)?A、小雞抓撓地面B、人閱讀信號(hào)/記號(hào)C、吊車吊起一桶混凝土D、作用于桶身上的重力3、一...親 可以全幫我翻譯一下么?1、一個(gè)物體,當(dāng)它所受到的各種力的功為0時(shí),它的速度是否會(huì)改變?2、下面哪種情況下,介質(zhì)做功了?并說明是正功還是負(fù)功A、小雞抓撓地面(那么這里地面就是介質(zhì))B、人閱讀符號(hào)C、吊車吊起一桶水泥D、作用在桶上的重力3、一個(gè)貨車用斜坡木(就是一塊三角形的木頭,搭在地面上,用以將東西推上火車)將家具推上貨車,在這個(gè)過程中,假如將斜坡木的長度增加,也就是講斜坡木和水平的角度變小,在將家具推上貨車的過程中,是否所做的功就變???解釋為什么4、一個(gè)鐘擺前后擺動(dòng),運(yùn)作正常,那么在擺動(dòng)的過程中,系者鐘錘的繩子是否對(duì)鐘錘做功了?重力是否對(duì)鐘錘做功了?解釋原因。5、兩輛完全一樣的汽車相向而行,到一定距離時(shí),兩車的駕駛員同時(shí)剎車,其中一輛車的剎車痕的長度是另外一輛剎車痕的2倍,假設(shè)剎車過程中,兩車受到的摩擦力大小相同,那么關(guān)于兩車的運(yùn)動(dòng),可以得出什么結(jié)論?6、一個(gè)賭球的人踢球,當(dāng)他的腳趾正在和球接觸的時(shí)候,他是否對(duì)球做功了?當(dāng)球剛好離開他的腳趾的時(shí)候,他是否對(duì)球做功了?球在飛行的過程中,是否有力在對(duì)球做功?7.一個(gè)人垂直抬起了一個(gè)質(zhì)量為4.5千克的水泥塊,垂直抬起距離為1.2米,然后又水平移動(dòng)了7.3米,問在這個(gè)過程中這個(gè)人做了多少功,重力又做了多少功?8.一團(tuán)東西,在一個(gè)星球上垂直方向所受到的重力為8.0 X 103千克。問這團(tuán)東西,從靜止的狀態(tài)起,以1.0米/平方秒的加速度向上抬起30米距離,各種力所做的功分別是多少??赡鼙欢饶锿塘?謝啦
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