Question

The average mass of rain drops is $3.0 \times 10^{-5}$ kg and their average terminal velocity is $9\, m/s.$ Calculate the energy transferred by rain to each square metre of the surface at a place which receives $100\, cm$ of rain in a year.

• A. $3.5 \times 10^5 J$
• B. $4.05 \times 10^4 J$
• C. $3.0 \times 10^5 J$
• D. $9.0 \times 10^4 J$

Answer 1

Answer: (B)

$4.05 \times 10^4 J$

Answer 2

$E = \frac{1}{2} \left(1 \times 0 \times 10^{4}\right) \times 81$
$= 500\times 81$
$= 40500\,J$
$= 4.05\times 10^{4}\,J$