1.

aneaimut aoh athenetassin the supemian paintsbetween thes iueadi lo aly and thema gmitudekna.g

Answer»

Arrangement are shown in attachment . Let θ is the angle made by string with vertical . Here tanθ = perpendicular/base = √{20² - 1²}/1 = √{399} ≈ 20 e.g., cosθ = base/perpendicular = 20{approximately}/20 = 1 Hence, cosθ = 1 and sinθ = perpendicular/hypotenuse= 1/20

Now, at equilibrium Tcosθ = mg { weight } -----(1) Tsinθ = F { electrostatic force between them } ------(2)

Now, F = kq₁q₂/r² Here , q₁ = q₂ = 2 × 10⁻⁸ C and r = 3cm = 0.03 m

Now, F = 9 × 10⁹ × 2 × 10⁻⁸ × 2 × 10⁻⁸/(0.03)² = 9 × 10⁹ × 4 × 10⁻¹⁶/9 × 10⁻⁴ = 4 × 10⁻³ N

Now, Tsinθ = 4 × 10⁻³ or, T × 1/20 = 4 × 10⁻³ [ sinθ = 1/20 }or, T = 4 × 20 × 10⁻³ = 0.08N Hence, tension in string is 0.08N

Now, Tcosθ = mgor, T × 1 = m × 10 [ g = 10 m/s²or, 0.08 = m × 10 ⇒ m = 0.008 Kg

Hence, mass of each ball is 8g

Thank u dear


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