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Xiao Ming rides a motorcycle from his home to the railway station. If he travels 30 kilometers per hour, he will travel 15 minutes earlier than the train; if he travels 18 kilometers per hour, he will travel 18 kilometers Now Xiao Ming is going to arrive at the railway station 10 minutes before the train starts. What's the speed of his motorcycle
15 minutes = 1 / 4 hour
The time to arrive at the railway station on time is x hours
30（X－1/4）＝18（X+1/4）
30X－15/2＝18X+9/2
12X＝12
X＝1
Xiao Ming's journey from home to the railway station
＝30×（1-1/4）
＝30×3/4
= 45 / 2 (km)
10 minutes = 1 / 6 hour
Now Xiao Ming plans to arrive at the railway station 10 minutes before the train starts, so the speed of his motorcycle should be
（45/2）÷（1-1/6）
＝45/2×6/5
= 27 (km / h)
Xiao Ming rides a motorcycle from home to the railway station. If he travels at a speed of 30km / h, it will be 15min earlier than the train's start time. If he travels at a speed of 18km / h, it will be 15min later than the train's start time. Now he plans to arrive at the railway station 10 minutes before the train's start. What's the speed of the motorcycle?
Suppose Xiao Ming's distance from home to the railway station is x kilometers
x30+1560=x18-1560
x=22.5
How can I calculate the speed after I calculate the distance?
15min = 1 / 4h, the distance between Xiaoming's home and the railway station is x km ﹥ X / 30 + 1 / 4 = x / 18-1 / 4 x / 18-x / 30 = 1 / 2, 12x = 270 x = 22.5, 10min = 1 / 6h, the speed of motorcycle should be YKM / h ﹥ 22.5 / 30 + 1 / 4 = 22.5 / y + 1 / 6, 22.5 / y = 5 / 6, y = 27
Li Wei rides a motorcycle from his home to the railway station. If he travels 30km per hour, it will be 15min earlier than the train. If he travels 18km per hour, it will be 15min later than the train. Now Li Wei plans to arrive at the railway station 10 minutes before the train starts. How fast should Li Wei ride a motorcycle at this time?
It takes x hours to arrive on time
Then 30 (x-0.25)) = 18 (x + 0.25)
x=1
Set the speed of Li Wei's motorcycle to arrive at the railway station 10 minutes before departure as t
Then 30 (1-0.25) = t (1-1 / 6)
t=27
Li Wei's motorcycle speed at this time was 27 kilometers per hour
A and B drive in the same direction from the same place. A moves in a straight line at a uniform speed, v = 20m / s
When car B reaches 2000 meters away from the starting place, it begins to overtake car a with the initial speed of zero and the acceleration of a = 2m / S2?
When the speed of car a is just equal to that of car B, the distance between the two workshops is the largest
v'=at=v=20m/s
The solution is t = 10s
The displacement of car a relative to the starting point is s = 2000m + VT = 2200m
The displacement of vehicle B relative to the starting point s' = (at ^ 2) / 2 = 100m
The maximum distance between the two workshops before car B overtakes car a is L = S-S' = 2100m
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