The best thing to do is start out small. Do something that is in your comfort zone and get bigger each time. Before you know it, you will have gotten over your fear and it'll feel great :)
Answer:
The BOD concentration 50 km downstream when the velocity of the river is 15 km/day is 63.5 mg/L
Explanation:
Let the initial concentration of the BOD = C₀
Concentration of BOD at any time or point = C
dC/dt = - KC
∫ dC/C = -k ∫ dt
Integrating the left hand side from C₀ to C and the right hand side from 0 to t
In (C/C₀) = -kt + b (b = constant of integration)
At t = 0, C = C₀
In 1 = 0 + b
b = 0
In (C/C₀) = - kt
(C/C₀) = e⁻ᵏᵗ
C = C₀ e⁻ᵏᵗ
C₀ = 75 mg/L
k = 0.05 /day
C = 75 e⁻⁰•⁰⁵ᵗ
So, we need the BOD concentration 50 km downstream when the velocity of the river is 15 km/day
We calculate how many days it takes the river to reach 50 km downstream
Velocity = (displacement/time)
15 = 50/t
t = 50/15 = 3.3333 days
So, we need the C that corresponds to t = 3.3333 days
C = 75 e⁻⁰•⁰⁵ᵗ
0.05 t = 0.05 × 3.333 = 0.167
C = 75 e⁻⁰•¹⁶⁷
C = 63.5 mg/L
The answer of <span> the change in electric potential difference is</span> -1.0 × 10^7 V. It is defined as the work done per unit charge. A potential difference of 1 V means that 1 joule of work is done per coulomb of charge or 1 V = 1 J C-1.
The heat capacity is given by the expression:
When the 
is measured in the calorimeter, we obtain a value, and since we know the mass of the material and we control the change in 
, we can then determine the specific heat "C" by simply remplazing in the expression.
Condensation, radiation, convection, conduction are many ways heat is transferred from atmosphere to ocean. however heat comes from the sun then, to the atmosphere.
