Question:medium

A stone is dropped from a height of 45 m. What is the time taken for the stone to reach the ground?

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Remember: The equation \( s = \frac{1}{2} g t^2 \) is useful for calculating the time of fall under gravity, starting from rest.
Updated On: Nov 26, 2025
  • 3 s
  • 5 s
  • 6 s
  • 9 s
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The Correct Option is A

Solution and Explanation

Step 1: Apply the equation of motion For an object released from rest, the distance covered under constant gravitational acceleration is described by:\[s = \frac{1}{2} g t^2\]Where:- \( s \) represents the distance traveled (45 m).- \( g \) denotes the acceleration due to gravity (approximately \( 9.8 \, \text{m/s}^2 \)).- \( t \) is the duration of the fall (the unknown).Step 2: Insert provided data Substitute \( s = 45 \, \text{m} \) and \( g = 9.8 \, \text{m/s}^2 \) into the equation:\[45 = \frac{1}{2} \times 9.8 \times t^2\]Simplify the equation:\[45 = 4.9 \times t^2\]Isolate \( t^2 \):\[t^2 = \frac{45}{4.9} \approx 9.18\]Calculate \( t \):\[t = \sqrt{9.18} \approx 3 \, \text{seconds}\]Conclusion: The estimated time for the object to hit the ground is 3 seconds. This corresponds to option (1).
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