Arock is dropped from rest. how fast is it going after it has been falling for 9.2 s?

90.2 m/s. A rock dropped from rest after it has falling for 9.2 seconds will have a velocity of 90.2m/s.

The bodies left in free fall increase their speed (downwards) by 9.8 m/s² every second. The acceleration of gravity is the same for all objects and is independent of the masses of these. In the free fall the air resistance is not taken into account.

v = g*t

v = (9.8m/s²)(9.2s) = 90.2 m/s

the device is called “ rocket engine”

need to see circuit to get time constant