<u>Answer </u>
A. that the initial gravitational potential energy of the masses transformed into kinetic energy of the paddles and then to thermal energy in the water
<u>Explanation</u>
James Joule allowed some water to fall from a height of 1 foot. the water would turn a paddle wheel at the bottom causing a temperature of water to raise.
The height form which the water fell, mass and the temperature of water was measured and used to calculate mechanical equivalent of heat.
From the choices given the best answer is A. that the initial gravitational potential energy of the masses transformed into kinetic energy of the paddles and then to thermal energy in the water.
Answer:
0.0006091222 m
Explanation:
q = Charge = 42 pC
V = Voltage = 620 V
= Permittivity of free space = 
Electric potential is given by (at r = R)

The radius of the drop is 0.0006091222 m
The density is 4.76 gcm^-3
and if mass is in kg then density is equal to 4.76*10^-3