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प्रश्न
An aeroplane lands at 216 kmh−1 and stops after covering a runway of 2 m. Calculate the acceleration and the time, in which it comes to rest.
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उत्तर
Initial velocity = u = 216 kmh−1
u = `216xx5/18` = 60 ms−1
Final velocity = v = 0
Distance = S = 2 km = 2000 m
v2 − u2 = 2aS
(0)2 − (60)2 = 2a (2000)
4000 a = −3600
(Acceleration) a = `(-3600)/4000`
= −0.9 ms−2
Now, v = u + at
0 = 60 + (−0.9)t
0.9t = 60
(Time) t = `60/0.9=600/9` = 66.67 S
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