Answer:
Part A:
Distance=864000 m=864 km
Part B:
Energy Used=ΔE=8638000 Joules
Part C:

Explanation:
Given Data:
v=20m/s
Time =t=12 hours
In Secs:
Time=12*60*60=43200 secs
Solution:
Part A:
Distance = Speed**Time
Distance=v*t
Distance= 20*43200
Distance=864000 m=864 km
Part B:
Energy Used=ΔE= Energy Required-Kinetic Energy of swans
Energy Required to move= Power Required*time
Energy Required to move=200*43200=8640000 Joules
Kinetic Energy=

Energy Used=ΔE=8640000 -2000
Energy Used=ΔE=8638000 Joules
Part C:
Fraction of Mass used=Δm/m
For This first calculate fraction of energy used:
Fraction of energy=ΔE/Energy required to move
ΔE is calculated in part B
Fraction of energy=8638000/8640000
Fraction of energy=0.99977
Kinetic Energy=
Now, the relation between energies ratio and masses is:



Answer:
Length, l = 33.4 m
Explanation:
Given that,
Electrical field, 
Let the electrical potential is, 
We need to find the length of a thundercloud lightning bolt. The relation between electric field and the electric potential is given by :

So, the length of a thundercloud lightning bolt is 33.4 meters. Hence, this is the required solution.
Answer:
energy is stored is 2.2 × 10⁻¹³ J
Explanation:
The capacitance of the cell is given with the expression
C = (KE₀A) / d
k is the dielectric constant, A is the area of the cell, d is the thickness of the cell.
Now given that; the diameter is 50,
Area A = 4πR²
A = 4π × ( 25 × 10⁻⁶ m)²
A = 7850×10⁻¹² m²
our capacitance C = (KE₀A) / d
C = [9 ( 8.85 × 10⁻¹² C²/N.m² × 7850×10⁻¹² m² )] / 7×10⁻⁹ m
C = 8.93 × 10⁻¹¹ F
Now Energy stored
E = 1/2 × CV²
E = 1/2 × (8.93 × 10⁻¹¹ F) × ( 70 × 10⁻³ V)²
E = 2.2 × 10⁻¹³ J
Therefore energy is stored is 2.2 × 10⁻¹³ J