A ball is allowed to fall from rest from height h. If it travels 9/25th of total height in the last second of its fall then ball will hit ground will hit ground with speed
1. 45 m/s
2. 50 m/s
3. 30 m/s
4.35 m/s

Dear Student,

Please find below the solution to the asked query:

Supose time taken by the ball to fall is t.So height h is given by h=12gt2and distance travelled in last second, that is t'th second is given by ht=12gt2-12g(t-1)2Now according to given problem we have12gt2-12g(t-1)2=925×12gt2t=5, 59. Now taking time t as 5 second, and g as 10 ms-2 we can get the velocity at which the ball hit ground isv=gt=10×5=50 ms-1Option 2. is correct answer. 

Hope this information will clear your doubts about motion in a straight line.

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