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Physics · JEE | MOTION IN A STRAIGHT LINE
हिन्दीA ball is thrown vertically upwards from the top of a tower with a velocity of \( 20\text{ m s}^{-1} \). Taking \( g = 10\text{ m s}^{-2} \), what is the total time taken by the ball to hit the ground if the building height is \( 25.0\text{ m} \)?
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Correct answer · Option B
5 s
Explanation
Using \( y = y_0 + v_0 t + \frac{1}{2}at^2 \), \( 0 = 25 + 20t + \frac{1}{2}(-10)t^2 \implies 5t^2 - 20t - 25 = 0 \). Solving gives \( t = 5\text{ s} \).
