Question

After striking the floor a certain ball rebounds (4)/(5)th of its height from which it has fallen. The total distance that the ball travels before coming to rest if it is gently released from a height of 120 m is

• A. \(960\text{ m}\)
• B. \(1000\text{ m}\)
• C. \(1080\text{ m}\)
• D. Infinite

Hint:

For repeated rebounds, total distance =h(1+r)/(1-r).

Answer 1

The Correct Option is C

Step 1: Let initial height h=120 m and rebound ratio r=\frac45.
Step 2: Total distance travelled: S=h((1+r)/(1-r))
Step 3: S=120((1+\frac45)/(1-\frac45)) =120((9/5)/(1/5))=120×9=1080 m