A train starts from rest and accelerates uniformly at a rate of 2 m s -2 for10sec .it then maintains a constant speed for 200 s. the brakes are then applied and the train is uniformly retarted and comes to rest in 50s. Find 1.the maximum velocity reached 2.the retardation in the last 50s. 3.the total distance travelled 4.the average velocity of the train ?
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r1 = ut + 0.5gt^2
r2 = u(t-3) + 0.5g(t-3)^2
Equating these two equations:
3u = 0.5g[(t-3)^2 - t^2] = -0.5g[(2t-3)(3)] => u = -0.5g(2t-3)
Putting values and assuming positive y-axis in vertically upward direction, we have,
49 j = 0.5*9.8*(2t-3) j
or, (2t-3) = 10 or t = 6.5
r2 = u(t-3) + 0.5g(t-3)^2
Equating these two equations:
3u = 0.5g[(t-3)^2 - t^2] = -0.5g[(2t-3)(3)] => u = -0.5g(2t-3)
Putting values and assuming positive y-axis in vertically upward direction, we have,
49 j = 0.5*9.8*(2t-3) j
or, (2t-3) = 10 or t = 6.5
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