Answer:
Explanation:
The volume of contaminated water
= cross sectional area x height of water level
3.14 x 9 x 9 x 7.5 ft³
= 1907.55 ft³
mass = density x volume
= 1907.55 x 63.5 lbs
m = 121129.425 lbs
This mass has to be raised to the height of 8 ft before evacuation .
There is a rise of centre of mass of
8 - 7.5/2 ft
h = 4.25 ft
Energy required
= mgh
= 121129.425 x 32 x 4.25
= 16473601.8 unit.
Answer:
(a) 
(b) 
Explanation:
(a) The surface current density of a conductor is the current flowing per unit length of the conductor.

Considering a wire, the current is uniformly distributed over the circumferenece of the wire.

The radius of the wire = a

The surface current density 
(b) The current density is inversely proportional
......(1)
k is the constant of proportionality

........(2)
substituting (1) into (2)





substitute 

The rubber protects him from being electrocuted by the flow of current going through the plug.
Hope this helped!!
A. Solid turns into a gas