Arock drops from a height of 60 m. how long does it take for it to hit the ground

Here, Apply 2nd equation of the Kinematics :
S = ut + 1/2 at²
Here, s = 60 m
u = 0   [ free fall ]
a = 9.8 m/s²  [ constant value for Earth system ]

Substitute their values, 
60 = 0*t + 1/2 * 9.8 * t²
120 = 9.8t²
t² = 120 / 9.8
t = √12.24
t = 3.50 s

In short, Your Answer would be 3.50 seconds

Hope this helps!

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