Wood is typically an insulator(resists flow of electricity though it)
However, wet wood can be a conductor so really it depends
1) sound velocity reported by you : 292.39 m /s
2) time to travel 1620m at that velocity: t = d / v = 1620 m / 292.39 m/s = 5.54 s, since the moment the sound wave started.
3) You might wanted to tell the time since you watched the lightning.
Then you can calculate the time since the lighting was generated,1620 m away from you, until you saw it, using the speed of light:
speed of light = 3*10^8 m/s => t = 1620 m / (3*10^8m/s) =0.0000054 s
Then, this time is completely neglectible, and yet the answer is 5.54 s, as calculated in the step 2.
Answer:
Explanation:
Given
mass of ice 
Height of hill 
Neglecting air resistance
As resistance is absent so Energy at top of hill and at the bottom hill is conserved.
Energy at top is equal to Potential Energy

Energy at bottom is equal to kinetic energy at bottom



