Originally posted by zmerlinz
, i know that gravity speed is 9.8m/s
Merlin....You got something very wrong..

Gravity does not have speed.
What you mean by gravity is the effect of
Gravitational Force.

When a Body is subjected to a force it is accelerated.
This acceleartion due to gravity on a body above earth
has a average sealevel value of 9.81 m/second square.
The value of g is different at different places on earth.
9.81 is just an average value.

The value of g is different for different planets. moon
for example has a low g value of the order of 1 m/sec^2