Question

A train running at 20 ms–1 slows down at a rate of 1 ms–1 in every one second, till the train stops. Is the train acted upon by negative or positive acceleration and state its magnitude? pls help

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Answer 1

Given : A train running at 20 m/s slows down at a rate of 1 m/s in every one second, till the train stops.

To find: Is the train acted upon by negative or positive acceleration and state its magnitude?

Solution:

• Now we have given that  train running at 20 m/s slows down at a rate of 1 m/s in every one second, till the train stops. So:

                the initial velocity(u) of the train is 20 m/s  

                 the final velocity(v) of the train is 0 m/s

                Here, retardation(a) is -1 m/s^2 ......(negative acceleration)

• Now we know the formula:

                s = v^2 - u^2 / 2 a  

                s = ( 0 - 20^2) / 2(-1)

                s = -400 / -2

                s = 200

Answer:

              The train will stop after 200 m.