如图1所示，在长约1m的一端封闭的玻璃管中注满清水，水中放一个圆柱形的红蜡块R（圆柱体的直径略小于玻璃管的内径，轻重适宜，使它能在玻璃管内的水中匀速上升），将玻璃管的开口端用胶塞塞紧．将此玻璃管迅速竖直倒置（如图2所示），红蜡块R就沿玻璃管由管口A匀速上升到管底B．若在将玻璃管竖直倒置、红蜡块刚从A端开始匀速上升的同时，将玻璃管由静止开始水平向右匀加速移动（如图3所示），直至红蜡块上升到管底B的位置（如图4所示）．红蜡块与玻璃管间的摩擦很小，可以忽略不计，在这一过程中相对于地面而言（   ）

    Mike is in charge of(负责) a shopping center. He is a little worried these days because there is a new shopping center nearby and many of his customers (顾客) are now shopping there. Mike wants to do something to get them back. Before he starts, he gives out questionnaires (调查表) to shoppers. Here is one shopper, Miss Watson's questionnaire.

Questionnaire

⒈Age group：

口10—12口13—15口16—18√19 and over

⒉What do you think is important for a shopping center?

(Circle th6 number. 1 as the most important and 5 as the least important)

a) all kinds of shops         1  ② 3  4  5

b) beautiful window shows  1  2  ③  4  5

c) good prices          ①  2  3  4  5

d) lucky draw (抽奖) with great prizes 1  2  3  4  ⑤

e) sitting areas (区域)      1  ②  3  4  5

⒊Name five kinds of shops that you think should be in a good shopping center.

a) clothes shops

b) shoe shops

c) play areas for children

d) restaurants

e) movie theaters

⒋On which of the following do you spend most of your money?

(List 1, 2 and 3 with 1 as the most)

a) clothes 1  b) shoes   c) books and CDs 2  d) food. 3 others

    Thank you for taking the time me to fill in the questionnaire!

如图所示为一种加速度仪的示意图．质量为m的振子两端连有劲度系数均为k的轻弹簧，电源的电动势为E，不计内阻，滑动变阻器的总阻值为R，有效长度为L，系统静止时滑动触头位于滑动变阻器正中，这时电压表指针恰好在刻度盘正中．求：