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A stone dropped from the top of the tower is found to travel (5/9) of the height of the tower during the last second of its fall. The time of fall is?

Khushboo , 6 Years ago
Grade 11
anser 1 Answers
Khimraj

Last Activity: 6 Years ago

h = ½*g*t2   – (1)
distance travelled in last sec
d = 5h/9 = ½*g*(2t-1)               – (2)
then dividing (1) by (2)
9/5 = t2/(2t-1)
5t2 -18t +9 =0
5t2 -15t -3t +9 = 0
(5t-3)(t-3)=0
then t =3 sec 
Hope it clears. If you like answer then please approve it.
 

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