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. If the first ball takes 5s to reach the ground, then the difference in initial heights is (g = 10 ms-2)
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Answer 1

Answer:

80 m

Explanation:  Using, S = ut + 1/2 at²,

    For 1st body, a = g, u = 0 , t = 5

⇒ S₁ = 0(t) + g(5)²/2   ⇒ S₁ =  12.5 g

  For 2nd body, a = g, u = 0, t = 5-2 = 3

⇒ S₂ = 0(t) + g(3)²/2   ⇒ S₂ =  4.5 g

∴ Difference in heights:

   S₁ - S₂  = 12.5g - 4.5g

               = 8g

               = 8(10)

               = 80 m