CDS 2026 (I) General Knowledge, question 19

Topic: Physics

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Q19

An object is launched horizontally from a height of 45 m45\text{ m} above the ground with a speed of 10 m/s10\text{ m/s}. The time at which the object will hit the ground is : (Take g=10 m/s2g = 10\text{ m/s}^{2})

  1. (a) 6 s6\text{ s}
  2. (b) 4 s4\text{ s}
  3. (c) 3 s3\text{ s}Correct answer
  4. (d) 2 s2\text{ s}

Solution.

Answer: (c) 3 s3\text{ s}

  1. The launch is horizontal, so the initial vertical velocity is zero.
  2. Vertical free fall alone determines the impact time; the horizontal speed does not enter this calculation.
  3. h=12gt2,t=2hg=2×4510=3 sh = \frac{1}{2}gt^{2},\quad t = \sqrt{\frac{2h}{g}} = \sqrt{\frac{2 \times 45}{10}} = 3\, s