Tom ran around a ring track,which is 360 meters.During the first half of the whole time,his speed was 5 meters every second.During the second half,his speed was 4 meters every second.How many seconds did he spend on the second half of the whole way?

来源:学生作业帮助网 编辑:作业帮 时间:2024/11/16 03:19:09

Tom ran around a ring track,which is 360 meters.During the first half of the whole time,his speed was 5 meters every second.During the second half,his speed was 4 meters every second.How many seconds did he spend on the second half of the whole way?
Tom ran around a ring track,which is 360 meters.During the first half of the whole time,his speed was 5 meters every second.During the second half,his speed was 4 meters every second.How many seconds did he spend on the second half of the whole way?

Tom ran around a ring track,which is 360 meters.During the first half of the whole time,his speed was 5 meters every second.During the second half,his speed was 4 meters every second.How many seconds did he spend on the second half of the whole way?
速度乘以时间等于路程,总路程是360米,前半段时间的速度是每秒5米,后半段是每秒4米.由于Tom跑每秒5米和每秒4米都用了总时间的一半,设总时间的一半为x,故前段路程等于5x(速度乘以时间),后段等于4x(注:5x不等于一半路程,4x也是).两段路程合起来就是总路程,5x + 4x = 360.然后合并同类项和解方程,得x = 40.问题求的是后半段路程所用时间,路程的一半是180米.Tom最后用每秒4米的速度跑了4 × 40 = 160米,还有20米是用每秒5米的速度跑的,而这段一共是用了20 ÷ 5 = 4秒.这4秒加上后面换了速度跑的40秒,得出答案Tom一共用了44秒去跑后半段180米的路程.

Tom often ___ around the playground. A.run B.Tom often ___ around the playground.A.run B.runs Tom ran around a ring track,which is 360 meters.During the first half of the whole time,his speed was 5 meters every second.During the second half,his speed was 4 meters every second.How many seconds did he spend on the second half of the whole way? Tom get home ( )4 o' ciock.A.at around B .about C.about around D.around请说明原因(为什么答案不一致?) my daughter look around () me when she can't see me用介词填空the dog ran () me a long way and it kept barking () me. Tom likes t____ around the country. ran Tom was a black slave and he at last ______ the cotton farm to join the North Army.A.left B.escaped C.ran away D.fled John rens fast.Tom does not ran fast(合并成一句)Tom does not ran ______ ______ ______john he ran a red light Suddenly a man ran in. Tom ran away from home last year,and we ()ever since.A.would not see B.had not seen为什么 Rin英文 怎么读 rin怎么读? and it's the last thing you do with a cougarBut Tom broke and ran and that's the last thing you do with a cougar.这句话是说最有一件需要做的是ran,还是说ran是最不该做的一件事?能在举一个类似的例子么? Tom ran more quickly than l(句意相同)l_____ _____as______as Tom The speaker ________ his notes before the lecture.A) ran downB) ran intoC) ran outD) ran over -i_____ around all day.--oh,really?i'll make you a cup of coffee A.run B.ran C.have been running D.have run why not choice B 还有i'llmake you a cup of coffee 是什么用法 Bob,Marcia,and Tom had a race.Bob ran the race in 21seconds.Marcia's time was 23 seconds. Tom ran the race in 22 seconds.1.Marcia finish in_______________________place.She was the _________runner.2.Bob finished in_______________________place.He was t