Latest self Aptitude Question SOLUTION: After striking the floor, a ball rebounds to 4/5th of the height from which it fell. Find the total distance it travels before coming to rest if it is dropped from a height of 100

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After striking the floor, a ball rebounds to 4/5th of the height from which it fell. Find the total distance it travels before coming to rest if it is dropped from a height of 100 metres.

vikash singh (11 years ago)

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KAUSHIK CHAKRABORTY  (10 years ago)

It means the ball looses 1/5 of its height i.e 20% from 1 to 4/5 then from 4/5 to (4/5 - (4/5 * 1/5)) = 16/25
So it forms a G.P Series of..Multiplied by 2 because it goes up and comes down
(120 +2*(120* 4/5 + 120*16/25 +120* 64/125 + ...+ till Infinity )
=> 120 + 2*120 * (4/5 )/ (1 - 4/5)
=>120 + 960 =1080m
Total distance travelled will be 1080m

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Soureek Dey  (8 years ago)

it forms a G.P Series of..Multiplied by 2 because it goes up and comes down
(100 +2*(100* 4/5 + 100*16/25 +120* 64/125 + ...+ till Infinity )
=> 100 + 2*100 * (4/5 )/ (1 - 4/5)
=>100 + 800 =900 m
Total distance travelled will be 900m

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Sudipta Mukherjee  (10 years ago)

Infinite Geometric Series with a= 120 meters and r= 4/5


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Total distance = Sum = a[1/(1-r)] = 120[1/(1/5)] = 600 ft
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Soureek Dey  (8 years ago)

it forms a G.P Series of..Multiplied by 2 because it goes up and comes down
(100 +2*(100* 4/5 + 100*16/25 +120* 64/125 + ...+ till Infinity )
=> 100 + 2*100 * (4/5 )/ (1 - 4/5)
=>100 + 800 =900 m
Total distance travelled will be 1080m

Is this solution Helpfull? Yes | No   

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