Astone is thrown outward from the top of a 59.4-m high cliff with an upward velocity component of 19.5 m/s. how long is stone in the air?

There are 2 cases here:

a. The stone travels to another certain height until its velocity becomes 0.
i.e V² = u² - 2gh (given u = 19.5m/s)

When it reaches maximum height V = 0 
so, h = u²/2g = (19.5)²/(2*9.8) => h= 19.4m

b. Now the body starts to fall freely under gravity, so:
h = 1/2*gt²
We know maximum height reached by the body = height of building + height traveled after throw in (a)

or., t = √(2h/g)
or, t = √2*(19.4+59.4) /9.8 = 4 second

Ibelieve the answer is b. dugout

Efficiency is an action of doing something. for example when you take a test. good efficiency means you did well but bad effeciency or no effiency means you did bad.