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Grade 11Mechanics

Two trains A an B of length 400m each are moving on two parallel tracks with a uniform speed of 72 km/h in the same direction, with A ahead of B. The driver of B desires to overtake A and accelerates by 1 m/s². If after 50 s, the guard of B just brushes past driver of A, calculate the original distance between the guard of B and the driver of A.

Profile image of Ravi Kiran
9 Years agoGrade 11
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1 Answer

Profile image of Vikas TU
9 Years ago
Let speed of two trains be u and v individually. 
Relative speed of surpassing = u-v; 
Relative speed of intersection = u+v; 
Add up to length = 100+100 = 200m 
Time = Distance/speed; 
Surpassing time = remove/overwhelming pace; 
20 = 200/(u-v); 
u-v= 10; - (1.) 
Crossing time = remove/crossing speed; 
10 = 200/(u+v); 
u+v = 20; - (2.) 
Understand eqn (1.) and (2.) 
    2u = 30 => u = 15 m/sec 
    15 –v=10 => v = 5m/sec 
Speed of first prepare is 15 m/sec and other prepare has 5 m/sec speed.