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1. after striking the floor ,a ball rebounds 80% of the height from which it has fallen. find the total distance that it travels before coming to rest if it is dropped from a height of 120 cm.

1. after striking the floor ,a ball rebounds 80% of the height from which it has fallen. find the total distance that it travels before coming to rest if it is dropped from a height of 120 cm.

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1 Answers

Badiuddin askIITians.ismu Expert
148 Points
12 years ago

Dear sougata

Total distance travel by ball is

S = 120 + 2*120*.8 + 2*120*(.8)2  + 2*120(.8)3 +.................∞

i have multiplied by 2 because ball travells two time first when ball move from flour to vertically upward and second when it come back  to flour.

S = 120 + 2*120*.8[ 1 + .8 + (.8)2+......∞]  in bracket we have infinite geometric progression

  =120 + 192[ 1/(1-0.8)]

  =120 + 192[5]

  =1080   cm


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