OnlineCBT
Physics · MOTION IN A STRAIGHT LINE
हिन्दीA ball is thrown vertically upwards with an initial speed of \( 30\text{ m s}^{-1} \) under gravity. Taking \( g = 10\text{ m s}^{-2} \), find the ratio of the distances covered by the ball during the 1st, 2nd, and 3rd seconds of its upward journey.
Correct answer · Option 2
\( 5 : 3 : 1 \)
Explanation
Using \( s_n = u - \frac{g}{2}(2n-1) \): for \( n=1 \), \( s_1 = 30 - 5(1) = 25\text{ m} \); for \( n=2 \), \( s_2 = 30 - 5(3) = 15\text{ m} \); for \( n=3 \), \( s_3 = 30 - 5(5) = 5\text{ m} \). The ratio is \( 25 : 15 : 5 = 5 : 3 : 1 \).
