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# c2 Geometric progression

1. Hey Ive come across this question and I have no idea how they got their answer and why they did it.

A ball is dropped from a height of 2 metres. After each bounce it rebounds to a height 0.8 times the height that it reached after the last bounce.

(ii)
Find the total distance travelled by the ball before it comes to rest.

how did they derive this equation? 2+2sum infinite ... I understand the +2 part as thats the height it dropped from but otherwise I am confused.

2. (Original post by Polioz)
Hey Ive come across this question and I have no idea how they got their answer and why they did it.

A ball is dropped from a height of 2 metres. After each bounce it rebounds to a height 0.8 times the height that it reached after the last bounce.

(ii)
Find the total distance travelled by the ball before it comes to rest.

how did they derive this equation? 2+2sum infinite ... I understand the +2 part as thats the height it dropped from but otherwise I am confused.

The ball rebounds after it hits the surface, it first goes up then moves down, hence it is 2 times the sum to inifinity, we need to consider both the motions, of it moving up as well as moving down.
3. The ball has to fall from the height it gets to aswell....
4. (Original post by raheem94)
The ball rebounds after it hits the surface, it first goes up then moves down, hence it is 2 times the sum to inifinity, we need to consider both the motions, of it moving up as well as moving down.
ahaa that makes sense thank you

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