h = 1.4 m, the height the glass falls.
u = 0, initial vertical velocity, because the glass is knocked off a table.
Assume g = 9.8 m/s², and ignore air resistance.
Let t = the time for the glass to hit the ground.
Then
(1/2)*(9.8 m/s²)*(t s)² = (1.4 m)
4.9t² = 1.4
t² = 0.2857
t = 0.5345 s
Answer: 0.54 s (nearest hundredth)