问题 选择题

小亮和爸爸穿上潜水服,一起亲身体验了潜水员的感受。他们在水面下继续下潜的过程中(   )

A.所受浮力变大,压强变大

B.所受浮力变大,压强变小

C.所受浮力不变,压强不变

D.所受浮力不变,压强变大

答案

答案:D

题目分析:人下潜的过程中,所处深度h增大,排开水的体积V不变,

∵p=ρgh,Fgv,水的密度ρ不变,

∴他受到的压强变大,受到的浮力不变.

故选D.

点评:本题考查了学生对液体压强公式和阿基米德原理公式的掌握和运用,抓住下潜时深度变大、排开水的体积不变分析是本题的关键.

单项选择题
单项选择题

Strange things have been happening to England. Still (1) from the dissolution of the empire in the years (2) World War Ⅱ, now the English find they are not even British. As the cherished "United Kingdom" breaks into its (3) parts, Scots are clearly (4) and the Welsh, Welsh. But who exactly are the English What’s left of them, with everything but the (5) half of their island taken away

Going back in time to (6) roots doesn’t help. First came the Celts, then the Romans, then Angles, Saxons, Jutes, Danes. Invasion after invasion, until the Norman Conquest. English national identity only seemed to find its (7) later, on the shifting sands of expansionism, from Elizabethan times onwards. The empire seemed to seal it. But now there’s just England, (8) of a green island in the northern seas, lashed by rain, scarred by two (9) of vicious industrialization fallen (10) dereliction, ruined, as D.H. Lawrence thought, by "the tragedy of ugliness," its abominable architecture.

Of all English institutions, the one to (11) on would surely be the pub. Shelter to Chaucer’s pilgrims, home to Falstaff and Hal, throne of felicity to Dr. Johnson, the pub- that smoky, yeasty den of jollity-is the womb of (12) , if anywhere is. Yet in the midst of this national (13) crisis, the pub, the mainstay of English life, a staff driven (14) into the sump of history, (15) as the Saxons, is suddenly dying and evolving at (16) rates. Closing at something like a rate of more than three a day, pubs have become (17) enough that for the first time since the Domesday Book, more than half the villages in England no longer have one. It’s a rare pub that still (18) , or even limps on, by being what it was (19) to be: a drinking establishment. The old (20) of a pub as a place for a "session," a lengthy, restful, increasingly tipsy evening of swigging, is all but defunct.

14()

A.up

B.down

C.right

D.left