Two balls are dropped to the ground from different heights. One ball is dropped 2s after the other but they both strike the ground at the same time, after the first was dropped. If the difference in t

Question

Two balls are dropped to the ground from different heights. One ball is dropped 2s after the other but they both strike the ground at the same time, after the first was dropped. If the difference in the heights at which they were dropped is 40m then find the time for which second ball has remain in air (in sec) (Given: g = 10 ms − 2 )

TestHub · Accepted Answer

Let the first ball fall for t seconds. The second falls for t - 2 seconds.

$h_{1} = \frac{1}{2} g t^{2} = 5 t^{2}$

$h_{2} = \frac{1}{2} g (t - 2)^{2} = 5 (t - 2)^{2}$

$h_{1} - h_{2} = 5 (4 t - 4) = 40$

$t = 3 s$

$t - 2 = 1 s$

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