First of all I must warn you: weight units in Unity are not kilos, they are TONS.
This said, first of all you should probably give an IMPULSE of force with adequate power (much more) and NOT every frame, so it will only be given to the object in one frame.
If instead you want to make it with the EVERY FRAME option, then add an action WAIT after that action, with the time you want the power added, add another state like END or something, and in the WAIT action set FINISHED and go to the END state.