Answer:
"h" signifies Planck's constant
Explanation:
In the equation energy E = h X v
The "h" there signifies Planck's constant
Planck's constant is a value, that shows the rate at which the energy of a photon increases/decreases, as the frequency of its electromagnetic wave changes.
It was named after Max Planck who discovered this unique relationship between the energy of a light wave and its frequency.
Planck's constant, "h" is usually expressed in Joules second
Planck's constant = 
It’s either C or D. let me know but I would do C!
Answer:
effeciency n = = 49%
Explanation:
given data:
mass of aircraft 3250 kg
power P = 1500 hp = 1118549.81 watt
time = 12.5 min
h = 10 km = 10,000 m
v =85 km/h = 236.11 m/s
kinetic energy
kinetic energy 
gravitational energy 
total energy 
effeciency n = = 49%
R = 2.06 mm = 2.06 x 10^(-3) m
Q = 1.6 x 10^(-19) C
v = 2.5 x 10^(-5) m/s
I = 8 A = 8 C/s
A = r² π = ( 2.06 x 10^(-3) ) ² x 3.14 = 13.325 x 10^(-6 ) m² =
= 1.3325 x 10^(-5) m²
I = n Q v A
n = I / (Q v A)
n = 8 C/s / ( 1.6 x 10 ^(-19) * 5.4 x 10^(-5) * 1.3325 x 10^(-5) ) =
= 0.694 x 10^(29) m^(-3)
n = 6.94 x 10^(28) m^(-3)
