高一物理匀变速直线运动规律的应用-PPT精选

匀变速直线运动 规律的应用
．位移和时间的关系
v
vt
注意：当a方向和vo方向 相反（作减速运动）时，
v0
a取负值。
t/2 t
位ห้องสมุดไป่ตู้公式：
svo2 vt tvot1 2a2tvt
平均速度公式： v vo vt 2
（仅适用于匀变速直线运动）
＝V t/2 等于中间 时刻的瞬时速度
(3)匀变速直线运动的图象
1
S=v0t+ 2 at2……（2）
当V0=0时
1 S= 2 at2
（位（移2移2与））与时初 初时 间速 速间 的度 度的 平为 为平 方零零方成的的成正匀匀正比加变比。速速直直线线运运动动的的物 物体 体的位
（（54））初初数数为为零零的的匀匀加加速速直直线线运运动动的的物物体体通通过过连连 续续相位同移位的移时的间时比间为之比为
对于匀变速直线运动 ，有：
vvtv01 .85m /s3 .4 m /s 22
又S＝ vt
，所以t＝
s v
＝25s
巩固练习
1．汽车以10m/s的速度匀速行驶，在距车站25m时 开始制动，使车减速前进，到车站时恰好停下，求汽 车匀减速行驶时的加速度的大小为多少？
2．一个物体在3s内通过了位移30m， 同时它的速度变为原来的4倍．如果物 体做匀加速直线运动的物体，求物体的 加速度————。
VA
A
s
VB
B
sciave/ 最准的免费时彩计划软件
CHAPTER I A STROLLING PIANO“Why did she choose ‘Morning-Glory’ as her tribe name?” asked M?nkw?n the Rainbow of Sesooā the Flame, as Rainbow and Flame, with girlish arms entwining, stood beneath the shelter of the Silver Twins, two kingly birch -trees, so identical in stature even to their topmost jeweled crowns of leaves flashing in the July sun, so alike in the silver symmetry of each fair limb as to be named the Twins .These silver kings were one-hearted, too, in their benevolent purpose in life, which was to unite in casting a brotherly shade over a certain corner of the broad city playground, dotted with children from every clime, and incidentally to fan the flushed cheeks of the two girls directly benea th them, bound together by a girdling rainbow that played about their waists, woven by the sun’s shuttle amid the quivering birch -leaves, fit symbol of their binding Camp Fire sisterhood.Sesooā’s eyes danced, lit by a tiny golden flame that uncurled itself in their demure hazel like a firefly alighti ng on a brown leaf. She caught her lower lip between the pretty incisors that decorated the front of her mouth as she scrutinized the semi -distant figure of a sixteen-year-old girl—perhaps nearer to seventeen—clad in a loose lavender smock to her knees, whence to her ankles there was a gleam of white sk irt, with the most bewitching, frilled summer “Tam” of lavender, matching her smock, shielding her brown head, sheltering her face, like the hoo d of a flower. This floral figure leaned against the open door of a handsome automobile which was standing upon the playground avenue.“I’m sure i t’s beyond me to tell why Jessica Holley (Jessica Dee Holley; she always likes to bring the unusual little middle name in, because it was her mothe r’s, I suppose), why she chose Welatáwesit, which is the only Indian equivalent she could find for Morning-Glory—literally meaning ‘Climbing Plant’ or ‘Pretty Flower’ for her Camp Fire name. But I believe there’s a story attached to the choice, some ‘cunning’ little anecdote of her childhood. Wi sh I could ferret it out! She seems, always, to have been called ‘Glory,’ nearly as much as Jessica,” answered Sesooā racily, she who in every -day life bore no flaming cognomen, but was plain little, gay little, Sally Davenport, as full of quips and quirks, of lightning impulses and sudden tu rns as the wheeling firefly in her eyes.“Goody! I’d like to hear the anecdote, too. The Morning-Glory name suits her so well that I thought she must have dreamed it—that it came to her in sleep—as I dreamed mine,” laughed the Rainbow, whose rightful name when she was not clad in a leather -fringed robe of khaki, in moccasins and head-band, and seated by a Council Fire, was Arline Champion. “But I call it absurd, meanly absurd, that if there’s any stor y about her and her name, we should not hear it, we who have named our Camp Fire (and it’s the best in the city, too, though I say it myself!), o ur whole group or tribe of fourteen girls, after her,” she went on with a stamp of her foot on the playground sod and with rainbowed emphasis; she was t he shell-tinted, demurely shining kind of fifteen-year-old girl who unconsciously aims at carrying a rainbow in her pocket, to brighten the dull or tear -wet day.“Oh! we didn’t exactly ‘name it after her,’” demurred Sally. “She happened to come here last winter to visit those rich girls, the Deerings, who are all fluff an’ stuff; that exactly describes them, Olive and Sybil——” There was the least little green tinge of the spitfire about Sesooā’s flame now as she shot a glance toward two girls seated in the waiting automobile together with an older woman, evidently chaperon to the band of girl s. “Oh! I say, pinch me; I shouldn’t have said that, should I, seeing that they brought us here in their car? But ’twas the first time they ever did it, though my father is head-bookkeeper in their father’s office at the Works; and I’ll engage ’twas Morning-Glory—Jessica—who suggested it, as we all wanted to visit this playground where there are so many foreign children, to see them dance their folk dances,” she ran on, speech flitting away f rom its starting-point in the wake of her firefly dance, which vivaciously hovered from one object or group of objects to another.Arline waited for it to alight again on Jessica, as it presently did.“Well! as I was saying,” reverted Sally, “you remember how she came here last February just when we were beginning to organize our Camp Fire group, when we had secured Miss Darina Dewey as Guardian (I think she’s a love of a Guardian and I like her unu sual first name, too, though some of the girls don’t!) but before we had applied for our Charter, when we were searching for a name for our new Cam p Fire circle, raking over Indian names like leaves until—goodness! we seemed half-smothered in them.” Sally paused for breath, breathlessly smothered, indeed, by the sunlit torrent of her own words, which had a trick of inundating a listener.“It was at our second meeting, I think, at Miss Dewey’s house,” she went on, “that Jessica came in, all snow an’ sparkle from her eyes to her toes, and introduced herself by showing a transfer card sign