Aball rolls off a tall shelf with a horizontal speed of 2 m/s. the shelf is 1.29 m high. how long will it take for the ball to strike the ground?

consider the motion of the ball in vertical direction after it rolls off the shelf

v₀ = initial velocity in vertical direction just after it leaves shelf = 0 m/s

Y = vertical displacement = height of the shelf = 1.29 m

a = acceleration of ball = acceleration due to gravity = 9.8 m/s²

t = time to strike the ground

Using the kinematics equation

Y = v₀ t + (0.5) a t²

1.29 = (0) t + (0.5) (9.8) t²

1.29 = 4.9  t²

t² = 1.29/4.9

t² = 0.2633

t = √ 0.2633

t = 0.51 sec

hence the ball strike the ground after 0.51 sec