on a railway track a driver applies the brakes of the train at a yellow signal, a distance 1 km from red , where
it stops. The max deceleration of the train iş 0.2 m/s. Assuming uniform deceleration
what is the maximum safe speed of the train at the yellow signal? 2012- 65 Eng:
(a) 20 m/s (b) 40 m/s (c) 200 m/s (d) 400 m/s
Answers
Answered by
35
Answer:
20 m/s
Explanation:
on a railway track a driver applies the brakes of the train at a yellow signal, a distance 1 km from red , where it stops. The max deceleration of the train iş 0.2 m/s.
Let say speed at Yellow signal = U m/s
V = final speed = 0 m/s
a = acceleration = - 0.2 m/s (as deceleration)
S = distance = 1 km = 1000m
V² - U² = 2aS
=> 0² - U² = 2(-0.2)*1000
=> -U² = - 400
=> U² = 400
Taking square root both sides
=> U = 20
the maximum safe speed of the train at the yellow signal = 20 m/s
option a is correct
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