问几道英语物理题.急.1.A train travelling at 20ms(-1次方),starts to accelerate with constant acceleration.It covers the next kilometre in 25 seconds.Use the equation s=ut+1/2at² to calculate the acceleration.Find also how fast the trai

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问几道英语物理题.急.1.A train travelling at 20ms(-1次方),starts to accelerate with constant acceleration.It covers the next kilometre in 25 seconds.Use the equation s=ut+1/2at² to calculate the acceleration.Find also how fast the trai
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问几道英语物理题.急.1.A train travelling at 20ms(-1次方),starts to accelerate with constant acceleration.It covers the next kilometre in 25 seconds.Use the equation s=ut+1/2at² to calculate the acceleration.Find also how fast the trai
问几道英语物理题.急.
1.A train travelling at 20ms(-1次方),starts to accelerate with constant acceleration.It covers the next kilometre in 25 seconds.Use the equation s=ut+1/2at² to calculate the acceleration.Find also how fast the train is moving at the end of this time.Illustrate the motion of the train with a velocity-time graph.
How long does the train take to cover the first half kilometre?
2.A train travelling at 55ms(-1次方)starts to accelerate,and 200 metres later she is riding at 7ms(-1次方),Find her acceleration,assumed constant.

问几道英语物理题.急.1.A train travelling at 20ms(-1次方),starts to accelerate with constant acceleration.It covers the next kilometre in 25 seconds.Use the equation s=ut+1/2at² to calculate the acceleration.Find also how fast the trai
题目翻译过来应该是这样
1、一列火车以20米每秒的初速度开始以恒定的加速度加速,该火车在25秒内通过了1千米.运用公式s=ut+1/2at² 计算加速度.同时求火车在通过1千米时的末速度.用速度-时间图像表示火车的运动情况.
求火车通过前500所用的时间.
答:根据公式s=vt+1/2at² ,v=20,t=25,s=1000,解方程得到加速度a=8/5.
1km处的末速度vt=v+at=20+(8/5)*25=60
速度-时间图像没有画出,只需把握:匀变速运动的速度-时间图像为一直线,加速度为直线斜率,结合初速度和末速度以及时间,较易画出.
前500m所用时间,根据公式s=vt+1/2at² ,v=20,a=8/5,s=500,解方程得到t=[±25(根号5-1)]/2 取正数t≈25×0.618=15.45秒.
2、一列火车以55米每秒的初速度开始加速,经过200米后火车的速度为7米每秒,求加速度,假设加速度为一常数.
答:根据公式S=【vt的平方-v0的平方】/2a v0=55 vt=7 s=200 解得a=-7.44米每秒的平方.
可见火车是做匀减速运动.
你们这是搞双语教学吗?