Question

A stone is dropped from the top of a tower and travels 24.5 metre in the last second of its journey. Find the height of the tower?

Answer 1

Answer:

Distance travelled in the last second of its fall is Sn = 24.5m Also, Sn = ut + a(n – 1/2) But u = 0, a = g ∴ Sn = 0 + g(n – 1/2) 24.5 = 9.8n – 4.9 n = (24.5 + 4.9)/9.8 = 3 seconds. we know that S = ut + 1/2 at2 ∴ Height of the tower; h = 0 × 3 + 1/2 × 9.8(3)2 (∵ s = h, u = 0, a = g = 9.8m/s) ∴ h = 0 + 4.9(3)2 = 44.1m.