Answer:
a) 
b) 
Explanation:
Given:
- mass of raindrops,
- charge on the raindrops,
- horizontal distance between the raindrops,
A)
<u>From the Coulomb's Law the force between the charges is given as:</u>
we have:
<em>Now force:</em>
B)
<u>Now the acceleration on the raindrops due to the electrostatic force:</u>
The earth's liquid outer core is the major cause of the earth’s magnetic field.
<h3>
What is magnetic field?</h3>
The magnetic influence on moving electric charges, electric currents, and magnetic materials is described by a magnetic field, a vector field. A force acting on a charge while it travels through a magnetic field is perpendicular to both the charge's motion and the magnetic field. The magnetic field of a permanent magnet attracts or repels other magnets as well as ferromagnetic elements like iron. A magnetic field that varies with location will also exert a force on a variety of non-magnetic materials by changing the velocity of those particles' outer electrons. Electric currents, like those utilised in electromagnets, and electric fields that change over time produce magnetic fields that surround magnetised things.
To learn more about magnetic field,visit:
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Earthworm have bones Some children confuse earthworms, which are invertebrates and have no bones, with snakes which are vertebrates and do have a bony skeleton and many ribs.
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
