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Physics · MOTION IN A STRAIGHT LINE
हिन्दीReferring to the schematic motion diagram shown in Fig. 2.6, a ball is thrown vertically upwards from point A (top of a building of height \( y_0 = 25 \text{ m} \)) with an initial speed \( v_0 = 20 \text{ m/s} \). It reaches its peak position B and then falls down to point C on the ground. Taking \( g = 10 \text{ m/s}^2 \), calculate the ratio of the time taken by the ball to travel from A to B (\( t_{AB} \)) to the time taken to travel from B to C (\( t_{BC} \)).
Correct answer · Option 1
\( 2 : 3 \)
Explanation
From A to B: \( 0 = 20 - 10 t_{AB} \implies t_{AB} = 2.0 \text{ s} \). Height of B above ground = \( 25 + \frac{20^2}{2(10)} = 25 + 20 = 45 \text{ m} \). From B to C: free fall from rest through \( 45 \text{ m} \implies 45 = \frac{1}{2}(10) t_{BC}^2 \implies t_{BC} = 3.0 \text{ s} \). Ratio \( t_{AB} / t_{BC} = 2 / 3 \).
