3 An object is thrown with a horizontal velocity of 20 air r

3. An object is thrown with a horizontal velocity of 20 air resistance is negligible, the time that it takes the object to fall to the ground from the cliff is most nearly (A) 3 s (B) 5 s

Solution

h = ut + 0.5gt^2

Here Initial vertical velocity , u = 0, since the object is thrown horizontally

125 = 0*t + 0.5*9.81*t^2

125 = 4.905*t^2
t = 5.05 s

So option is (b) 5 s