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功的计算1.直接利用功的计算公式W=Fs进行计算.已知作用在物体上的力F和在力的方向上通过的距离s,可直接利用功的计算公式W=Fs来计算功.例1在水平地面上,用50 N的水平拉力拉重为100 N的小车,使小车沿水平方向前进了5 m,这时拉力所做的功是().A.50 J B.250J C.750 J D.0解析:在应用功的计算公式之前,应该先判断某个力是否对物体做了功,即物体在该力的作用下,是否在该力的方向上移动了一段距离.本题中,小车在水平拉力的作用下,水平移动了一段距离,所以拉力做了功.拉力做功W=Fs=50 N×5 m=250 J.答案:B
Calculation of work 1. Direct calculation of work using the formula W = Fs Calculate the known force F acting on the object and the direction of the force through the distance s, the work can be calculated directly using the formula W = Fs to calculate work Example 1 On a level ground, pull a car of 100 N with a horizontal pull of 50 N to move the car 5 m horizontally and the work done by the pull force is () A.A.50 J B.250J C.750 J D.0 Resolution: Before applying the formula for calculating work, you should first judge whether a force has made a work on the object, that is, whether the object moves a distance in the direction of the force under the force In this problem, the car moves horizontal by a certain distance under the action of horizontal pull, so the pulling force does work. The work force of pulling force is W = Fs = 50 N × 5 m = 250 J. Answer: B