SOLUTION: 1. a train travelling along a straight line with constant acceleration is observed to travel consecutive displacements of 1km in times of 30s and 60s respectively. find the initial

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Question 1001158: 1. a train travelling along a straight line with constant acceleration is observed to travel consecutive displacements of 1km in times of 30s and 60s respectively. find the initial velocity of the train.
2.a stone is dropped from the top of the building 20m high. a second stone is dropped from half-way up the same building find the time that should elapse between the release of the two stones if they are to reach the ground at the same time

Answer by ikleyn(52787) (Show Source):
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2. A stone is dropped from the top of the building 20m high. A second stone is dropped from half-way up the same building. Find the time that should elapse between the release of the two stones if they are to reach the ground at the same time.
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The dropped stones have zero initial velocity.

So, h= , where g is free fall acceleration 9.81 , t is time in seconds and h is the traveled distance (the height) by the falling body.

Thus we have two equations for two falling bodies:

20 =

and

10 = .

Find and from these equations.

Then - would be your answer.