Answer:
Explanation:
E=(σ/ε0)
As noted by Dirac the field is the same no matter how far you are from the sheet. When your charge covers a conducting plane, as in your case, the field is, D/eo ,(D is charge density). Because the field inside the conductor (no matter how thin) is zero. The only time the field is, D/2eo, is when you have just a sheet of charge, by itself, not on a conducting plane."
After 20 s, the motorcycle attains a speed of

and it continues at this speed for the next 40 s. So at 45 s, its speed is 80 m/s.
<h2>
Depth of river is 4.48 m</h2>
Explanation:
Discharge = Area x Velocity
Discharge of river = Discharge of stream 1 + Discharge of stream 2

Area of stream 1 = w₁ x d₁ = 8.9 x 3.8 = 33.82 m²
Area of stream 2 = w₂ x d₂ = 6.5 x 3.9 = 25.35 m²
Velocity of stream 1 = 2.3 m/s
Velocity of stream 2 = 2.6 m/s
Velocity of river = 3 m/s

Substituting

Depth of river = 4.48 m