题干

为研究太阳系内行星的运动,需要知道太阳的质量,已知地球半径为R,地球质量为m,太阳与地球中心间距为r,地球表面的重力加速度为g地球绕太阳公转的周期为T.则太阳的质量为(   )

A:4π2r3T2R2g

B:T2R2g4π2mr3

C:4π2mgr3r3T2

D:4π2mr3T2R2g

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D

同类题4

           In ancient Egypt, a shopkeeper discovered that he could attract customers to his shop simply by making changes to its environment. Modern businesses have been following his lead,with more tactics(策略).

           One tactic involves where to display the goods. Foe example, stores place fruits and vegetables in the first section. They know that customers who buy the healthy food first will feel happy so that they will buy more junk food(垃圾食品)later in their trip. In department stores, section is generally next to the women’s cosmetics(化妆品) section:while the shop assistant is going back to find the right size shoe, bored customers are likely to wander over cosmetics they might want to try later.

           Besides, businesses seek to appeal to customers’ senses. Stores notice that the smell of baked goods encourages shopping, they make their own bread each morning and then fan the bread smell into the store throughout the day. Music sells goods, too. Researchers in Britain found that when French music was played, sales of French wine went up.

           When it comes to the selling of houses, businesses also use highly rewarding tactics. They find that customers make decision in the first few second upon walking in the door, and turn it into a business opportunity. A California builder designed the structure of its houses smartly. When entering the house, the customer would see the Pacific Ocean through the windows, and then the poll through an open stairway leading to the lower level. The instant view of water on both levels helped sell these $10 million houses.