12小时内 时针和分针可以形成几次180度

12次.每小时一次.

当然是二十四小时的服法

11

Everyone should have his/her dream even he/she has nothing on hand. I have remembered these words since day one. It is true that a ship sails at open sea with the chart; a hawk flies and glide with her wings freely. We, should have our dream to make life glared
In 2013, the national congress sessions attributed to the dreams and it came true. President Xi highlighted that the revitalized Chinese dream which touched everyone of our hearts.
In UK, there is a erected tomb of a famous Jewishphilosopher which crafted these words - I have many dreams in my life, and till this aging stage, I realized that if I could have changed myself then maybe I could change my country and even more, perhaps I could have change the entire world", the piece of wording is situated near the Collegiate Church of St Peter at Westminster.
Thousand miles of journey begins with a single step! Yes it is, we have to get the Chinese dream come true. It should start from small, start with oneself. My dream is to become an outstanding medical doctor/surgeon, in which I use my hands to save life, to give others hope. The writer Luxin's dream was to be a doctor. when he put his dream as compared to Chinese dreams, I am just wonder which is more essential?! He gave up medicine study as became a writer, he used pen instead of surgical knife. His virtuous voice passed through hundred years of life span but it is still very encouraging. My dream may not match his but to save life and cure sick people is a noble mission for me and it is wipping on me to strive forward.
Should we recall then during the WWII, how many our soldiers sacrified their lives not in the battle fields but on the surgical bed. It was because the poor equipped and outdated medical technology. We paid a very price for that. But now, thanks for the advanced technology, many uncurable illnesses can be handled easily. My dream is to work hard in school, strive for the best and spend my life, my youth for our motherland.
As of now, the historical batton has passed on to us now, we have to declared loud and clear that - Forget not yesterday pain, sorrowness or glories, the duty and mission ought to carry out today without fail, for tomorrow dream - we shall not stop persuing.

24+24=48分
50*48/60=40千米
75-50=25千米
40/25=8/5小时
75*8/5=120千米
开始走时剩余时间8/5+24/60=2小时
120/2=60千米/小时
题中12小时打错了吧?

从0点开始的12小时内 时针和分针重合的次数 每12小时时针走1圈 每1小时分针走1圈
时针和分针重合的次数= 12 - 1 +1 =12 因为要加上开始的一次

水本身会有蒸发的,但不会这么多,所以,你这里是漏水了,情况严重不严重关键是看你的水池在什么位置,是地上地下!不做工程,免费提供混凝土防水渗漏水修复专业技术咨询

一座水库,12小时的来水总量为Q(m³),每秒出库量为q(m³/s),那么12小时的出库量为43200q(m³)；
当Q>43200q,则12小时内的库容增量△Q=(Q-43200q)/(12小时)=[(Q/43200)-q](m³/s)
如果Q

若起始时刻不算,即十二点处只算一次,则分针和时针重合11次,将表盘用1至12标记,则在1,2之间,2,3之间,.10,11之间各有分针时针重合一次.而11,12之间,12,1之间分针与时针不重合.仅在12点处重合一次.
同样,分针和秒针每小时重合59次,12小时重合708次.
而时针和秒针每分钟重合一次,除了第一分钟,（或是说最后一分钟）.所以重合719次.

设石头下落时间为t,悬崖高为h.
则：
h=1/2*(gt^2)
h=340*(3.4-t)
解之得：h=3.25m
答：悬崖高约3.25米

解题思路：由电风扇的铭牌读出功率，由W=Pt求出其12h内消耗的电能，与电冰箱12h消耗的电能相比较，进行选择．

电风扇12h内连续运转消耗的电能：W=Pt=0.065kW×12h=0.78kW•h，冰箱耗电量0.5kW•h/24h，则12h内正常使用时耗电量为0.25kW•h所以，12h内连续运转的电风扇比正常工作的电冰箱消耗的电能多；
故选B

点评：
本题考点： 电功、电功率．

考点点评： 本题主要考查了电功和电功率的计算，属于直接套公式就可计算的问题，属于基本内容．但要注意公式W=Pt中各量的单位要配套．

总共有12次重合,但能够具体说出准确时间点的,只有0:0:0.

550÷（150÷3）=11小时,550箱的出口加工任务只需11小时就能完成.

1:05分→
2:10分→
3:17分→
4:22分→
5:28分→
6:33分→
7:38分→
8:43分→
9:48分→
10:55分→
因为11点的重合刚好是12点整,所以12个小时只重合了11次!→

dear alice,
First of all, I totally understand your feeling now. I have also met this kind of problems before. However, It is your own issue for not lending money to Angela. You don't have to feel upset. Although you are good friends, you both have your own life.
On the other hand, if you have spare money, you can also lend to her. The only thing you need to do is to ask her to write a receipt. In my opinion, if you are really close friends, she will pay your back soon. I guess she must be a good girl, too.
sincerely yours,
liu ming
不知道你们考试的具体格式和要求,所以只是按正常通用的样子写了一下.但我比较擅长的是议论文,这种不大是我的长项.但应该问题不大.有什么问题你可以追问.修改也没问题.

十一次
分别在
1点过5又11分之5分钟
2点过10又11分之10分钟
3点过16又11分之4分钟
4点过21又11分之9分钟
5点过27又11分之3分钟
6点过32又11分之8分钟
7点过38又11分之2分钟
8点过43又11分之7分钟
9点过49又11分之1分钟
10点过54又11分之5分钟
12点

就这个了望采纳

体积是50×21×1.8=1890立方米
时间是1890÷（2.5×60）=12.6小时
所以12小不够

电风扇12h内连续运转消耗的电能：W=Pt=0.065kW×12h=0.78kW?h，冰箱耗电量0.5kW?h/24h，则12h内正常使用时耗电量为0.25kW?h所以，12h内连续运转的电风扇比正常工作的电冰箱消耗的电能多；
故选B

12*60*15=10800次 就是10800升了

分针走一圈,会和时针重叠一次,但是分针走的时候,时针并不是静止不动的；原来分针每走12圈,时针自己也要走一圈；因此,对时针来说,分针只绕时针走了11圈,时针和分针重合了11次.

秒针的转动很快,可以不用考虑,主要看时针和分针的重合次数.
分针和时针,大约每一小时多一点重合一次,1点5分左右,2点十分左右,三点十五左右,一直到11点55后还有一次.这样就共有11次.最后12点时还有一次,就12次.
如过再加上开始的12点,则有13次
计算详细方法：
时针的角速度：一小时转2π*12 即2π*12弧度每小时
分针：2π每小时 即一小时转一圈
相遇一次的时间t
（t/分针角速度）-（t/时针角速度）=2π

4小时1片

11次.每1小时,分针转一圈.无论时针在什么地方,分针总是可以遇到时针,12个小时时针转12圈,但0点的不算,所以碰11次.其实这个问题不用数学计算的

在午夜零点以后,12小时内时针与分针11次重合的时刻如下：
1点5分27又3/11秒,
2点10分54又6/11秒,
3点16分21又9/11秒,
4点21分49又1/11秒,
5点27分16又4/11秒,
6点32分43又7/11秒,
7点38分10又10/11秒,
8点43分38又2/11秒,
9点49分5又5/11秒,
10点54分32又8/11秒,
12点整.

水管A每小时注水：1÷12=1/12
水管B每小时注水：1÷9=1/9
两管一起开,每小时注水：1/12+1/9=(12+9)/108=7/36
所以两管一起开,注满水池需要时间：1÷7/36=36/7(小时）
答：需要36/7小时才能注满.

1、115度.设角B=x,角C=y,则有2x+2y+50=180,所以x+y =65度,所以角BAC=65+50=115度
2、90度.由题可知,三角形OCD为等腰三角形,OC=OD,且CD=4米,过O作OE垂直CD,垂足为E,则DE=CE=2,因BC=2,所以OE=2,所以OE=CE=2,所以三角形OEC和三角形OED圴为等腰直角三角形,所以角EOC=45度,所以DOC=90度.
ok!

奥数回答可以,但要非常复杂的方程.不如加入一点物理的知识,还是奥数,但简单多了.
我们以时针为参照系,即假设时针没有动,那么相当于分针在以11/12倍原速顺时针转动（奥数好好学过的话应该看得懂）这样12个小时内分针转了11圈（在假设时针不动的情况下）.而在这过程中时针不动,所以分针每转一圈就会两次和时针成90度角,所以在12小时内分针时针成90度角有22次.

加入BaCl2无沉淀,再加氢氧化钠有沉淀即可

时针一小时走30度 分针1小时走360度 360÷(360-30)=360÷330=12/11 答案应为:如果算上两头重合,应为13次.算一头,12次,都不算,11次
每次重合到下一次重合相隔1小时5分钟.

3小时包50箱,因此550箱需要：550/50 *3=33小时,所以不能再12小时内完成.

一共是12次.
一个小时就一次.
你可以拿钟去试试!

有的地区还是有的,意思和红色应该是一样的,风力12级以上.上海在2005年麦莎台风的时候就发布了黑色的台风预警

由条件可得：
20＝4K+b
30=6K+b
由上面方程可得
K＝5,b＝0
故有y＝5x
若进水a小时,则有y＝5a