Answer:
300 m
Explanation:
The train accelerate from the rest so u = 0 m/sec
Final speed that is v = 80 m/sec
Time t = 30 sec
The distance traveled by first plane = 1200 m
We know the equation of motion [tex]S=ut+\frac{1}{2}at^2[/tex] where s is distance a is acceleration and u is initial velocity
Using this equation for first plane [tex]1200=0\times 30+\frac{1}{2}a30^2[/tex]
[tex]a=2.67\frac{m}{sec^2}[/tex]
As the acceleration is same for both the plane so a for second plane will be 2.67 [tex]\frac{m}{sec^2}[/tex]
The another equation of motion is [tex]v^2=u^2+2as[/tex] using this equation for second plane [tex]40^2=0+2\times 2.67\times s[/tex]
s = 300 m