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[主观题]
己知某轧钢机的原动机功率等于常数,P´=2600HP(马力),钢材通过轧辊时消耗的功率为常数,P"=4000HP,钢材通过轧辊的时间t"=5s,主轴平均转速n=80r/min,机械运转速度不均匀系数δ=0.1,求:(1)安装在主轴上的飞轮的转动惯量;(2)飞轮的最大转速和最小转速;(3)此轧钢机的运转周期。
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(1)如果P=1.00美元,需求的价格弹性为多少?交叉价格弹性又等于多少昵?
(2)如果垓商品的价格P上涨到2.00美元,那么现在需求的价格弹性为多少?交叉价格弹性昵?
Supuose: the demand curve for a producl is given by Q=10-2P+P,, where P is the price of the produet and P, is the price of a subtitute good. The price of the substitute god is S 2.00.
(a) SupposeP= S 1. 00. What is the price elasticity of demand? What is the cross-price elas- ticity of demand?
(b) Suppose the price of the good, P, inereases to $ 2.00. Now whal is the price clasticily of demand,and what is the cross-price elasticity of demand?
列车质量为m,其功率为常数P,如列车所受阻力F为常数,则时间与速度的关系为,如阻力F与速度v成正比,则
,试证明之。