A ball is dropped from rest from a height of 45 m. How long does it take for the ball to reach the ground?

Core Concept

Using the kinematic equation s = ut + (1/2)at², where s = 45 m (displacement), u = 0 m/s (initial velocity), and a = 9.8 m/s² (acceleration due to gravity), we get 45 = 0 + (1/2)(9.8)t² → 45 = 4.9t² → t² = 45/4.9 ≈ 9.18 → t ≈ 3.03 s, which is approximately 3.0 s.