Air pressure is gravity pulling down on air molecules.
a. true
b. false

Air pressure is gravity pulling down on air molecules. Like us, air has also mass and the pressure is brought down by the earth’s gravity causing an increase in weight exerted on you as you descend lower into the atmosphere. So, as you enter into the other layers of atmosphere above the troposphere, the air pressure starts to decrease. Below the atmosphere is the hydrosphere. This is where all liquid forms are located. And since the seawater has a greater mass than air, it has the greatest pressure. The answer is true.

The initial velocity would be
u^2 = 2*9.8*123
u^2 = 2410.8
u^2 = 49 m/s
the time period will be
49/9.8 = 5 sec