Question

After striking the floor, a rubber ball rebounds to 3/5th of the height from which it has fallen. Find the total distance that it travels before coming to rest if it has been gently dropped from a height of 20 metres. 

(a) 40 metres 

(b) 60 metres 

(c) 80 metres 

(d) 120 metres 

Answer 1

Correct option (c) 80 metres

Explanation:

The path of the rubber ball is: 

In the figure above, every bounce is 3/5th of the previous drop. 

In the above movement, there are two infinite G.Ps (The GP representing the falling distances and the GP representing the rising distances.) The required answer: (Using a/(1 − r) formula) (20/2/5 +12/2+5)= 80 metres.