Answer:
The velocity of the penny at 25th second is, v = 245 m/s
Explanation:
Given,
The time taken by the penny to hit the ground is, t = 30 s
The initial velocity of the penny, u = 0 m/s
The velocity of the penny at 25th second, v = ?
Using the II equation of motion, the displacement is given by the formula
               S = ut + ½ gt²
                   = 0 + ½ x 9.8 ( 25²)
                   = 3062.5 m
Using the III equations of motion
                v² = u² + 2gs
Substituting the given values,
                v² = 0 + 2 x 9.8 x 3062.5
                   = 60025
                v = 245 m/s
Hence, the velocity of the penny at 25th second is, v = 245 m/s
