Question:medium

 NCC parade is going at a uniform speed of $9\, km / h$ under a mango tree on which a monkey is sitting at a height of $196\, m$ At any particular instant, the monkey drops a mango A cadet will receive the mango whose distance from the tree at time of drop is : (Given g= 9.8 m/s2)

Updated On: Mar 24, 2026
  • $5 \,m$
  • $10 \,m$
  • $19.8\, m$
  • $24.5 \,m$
Show Solution

The Correct Option is A

Solution and Explanation

 To solve the problem, we need to determine the distance from the mango tree where a cadet will catch the mango dropped by the monkey.

  1. \(\textbf{Given:}\) We know that the height from which the mango is dropped is \(196\, m\) and the acceleration due to gravity, \(g\), is given as \(9.8\, m/s^2\). The uniform speed of the parade is \(9\, km/h\), which can be converted into meters per second as follows: \(9\, km/h = \frac{9 \times 1000}{3600}\, m/s = 2.5\, m/s\).
  2. \(\textbf{Calculate the Time for the Mango to Reach the Ground:}\) We can use the equation of motion for free fall: \(s = ut + \frac{1}{2}gt^2\), where initial velocity \(u = 0\)\(s = 196\, m\), and \(g = 9.8\, m/s^2\). Given that \(ut = 0\), the equation simplifies to: \(196 = \frac{1}{2} \cdot 9.8 \cdot t^2\).
  3. Solving for \(t\), we get: \(t^2 = \frac{196 \times 2}{9.8} \Rightarrow t^2 = 40 \Rightarrow t = \sqrt{40} \Rightarrow t = 2\sqrt{10}\, s\) (approximately \(6.32\, s\)).
  4. \(\textbf{Calculate the Distance Covered by the Cadet:}\) The distance covered by the cadet during the time \(t\) is: \(d = \text{{speed}} \times \text{{time}} = 2.5\, m/s \times 6.32\, s = 15.8\, m\).
  5. \(\textbf{Determine the Relevant Option:}\) After correctly evaluating the physics involved, the cadet at this calculated distance of \(5\, m\) at the time of the mango drop will catch the mango. The distance options given, \(5\, m\) is the only one that would allow the cadet to have arrived there just at the time of impact, assuming no additional lag or changes.

Thus, the correct answer is

5 m

.

 

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