Answers

2015-03-11T13:14:26+05:30
Velocity need to pierce 5 cm plank = 200 m/s
Velocity need to pierce 1 cm plank = 200/5 m/s
Velocity required to pierce 20 cm plank = (200×20)/5
= 4000/5
= 800 m/s
So, The velocity required pierce 20 cm plank is 800 m/s.
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