fluid mechanics

let both radius be r initially.

so initial vol = 4/3pir³

now, both coalesce to form a sphere of radius R.

4/3pi R³ = 2. 4/3 pi r³

=> R = r 2^1/3

now, from terminal vel formula,

v is prop to r²

so, v2/v1 = R²/r²

=> v2/1 = r² 2^2/3/r²

=> v2 = 2^2/3 ans.

volume is same
=> 2(4/3 Ï€r³)=4/3 Ï€R³
=>R=2^1/3r

and initially mg=6Ï€ n r v_old
finally 2mg=6Ï€ n R v_new

put the values

oh.....i am late,...............again........[2][2][2]

ya.... i think sky types much faster especially she is more familiar with powers, latex ones etc......