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Suppose you drop a ball from a window 30 meters above the ground. The ball bounces to 50% of its previous height with each bounce. What is the total number of meters (rounded to the nearest tenth) the ball travels between the time it is dropped and the ninth bounce?

 Jan 9, 2017

Best Answer 

 #1
avatar+37091 
+5

Before it bounces it travels 30 m

betweent the first and second bounce it goe UP 15 m  and down 15m    then the second bounce occurs.....etc

We are not counting the distance it travels AFTER the 9th bounce (per the question)

 

 

 30+ (2)(30 x .5)  +  (2) 30 x .5 x .5  +(2) 30 x .5x.5x.5  .....=  30+ 60 (.5 + .5x.5 + .5x.5x.5....) =30+ 60\(\sum_{1}^{8}\)  .5^n =

30 +60(.99609) = 89.765 m

 

Can anyone verify this????

Thanx  

 Jan 9, 2017
 #1
avatar+37091 
+5
Best Answer

Before it bounces it travels 30 m

betweent the first and second bounce it goe UP 15 m  and down 15m    then the second bounce occurs.....etc

We are not counting the distance it travels AFTER the 9th bounce (per the question)

 

 

 30+ (2)(30 x .5)  +  (2) 30 x .5 x .5  +(2) 30 x .5x.5x.5  .....=  30+ 60 (.5 + .5x.5 + .5x.5x.5....) =30+ 60\(\sum_{1}^{8}\)  .5^n =

30 +60(.99609) = 89.765 m

 

Can anyone verify this????

Thanx  

ElectricPavlov Jan 9, 2017
 #2
avatar+37091 
+5

= 89.8 m  (rounded to nearest tenth)

ElectricPavlov  Jan 9, 2017
 #3
avatar+129840 
0

I assume that you want the total distance between the time it is dropped and just before it bounces the ninth time

 

The sum is given by

 

30  +  30 [1 − .5^8] / [1 − .5 ]  =  89.76m → 89.8 m

 

Just as EP found....!!!!

 

 

cool cool cool

 Jan 10, 2017

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