Question

A train is travelling at the speed of 180 km/hr. In order to trap superman Lex Luthor has broken the tracks Unware of Luthor's evil intensions, superman tries to stop the train by pushing it in opposite direction Right at the moment when the train is 300 m away from the crack in the track, Superman is applying a deceleration of 5 m/s² Just after 2 sec a bullet laced with kryptonite hits superman which incapacitates him for a while. How long has super man got to remove the bullet and start to give deceleration so to protect the innocents? (Trains brake system has failed)

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Answer 1

Explanation:

Now according to your question the initial velocity of train is 180 km/hr that's 56.25 m/a

applying:

$v = u - at$

where, u=56.25

$a = 5 \: m \div {s}^{2}$

and t= 2s

v becomes 46.25 m/s which is the velocity affter application of power by superman

Now as superman becomes unconscious the retarding acceleration is removed and only 300 mts are left therefore,

$s = u \times t + 1 \div 2 \times a {t}^{2}$

where a=0

So, s=ut

t= s/v = 300/46.25= 6.28s

Therefore superman should take any action before this time.

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