Particle 1 carrying -4.0 μC of charge is fixed at the origin of an xy coordinate system, particle 2 carrying +8.0 μC of charge is located on the x axis at x = 4.0 m , and particle 3, identical to particle 2, is located on the x axis at x = -4.0 m . What is the vector sum of the electric forces exerted on particle 3? Determine the x and y components of the vector sum.

Respuesta :

Answer:

F = (2.7 10⁻² i ^ + 0j ^) N

Explanation:

The electric force is given by Coulomb's law

           F = k q₁q₂ / r²

Let's apply Newton's second law in particle 3

          F = F₃₁ - F₃₂

         F₃₁ = k q₃q₁ / r₃₁²

          F₃₂ = k q₃q₂ / r₃₂²

Let's write the values ​​they give us

          q₁ = -4.0 10⁻⁶ C

          x₁ = 0

          q₂ = q₃ = + 8.0 10⁻⁶ C

          x₂ = 4.0 m

          x₃ = -4.0 m

We look for the distances

          r₃₁ = x₃ -x₁

          r₃₁ = -4.0  - 0 = -4.0 m

          r₃₂ = -4.0 - 4.0 = -8.0 m

Let's write the force equation

          F = k q₃ (q₁ / r₃₁² + q₂ / r₃₂²)

           

   

Let's calculate

           F =  8.99 10⁹ 8 10⁻⁶  (4 10-6/4 2 - 8 10-6 / 8 2)

           F =  71.92 10³ (1/2 - 1/8  )10⁻⁶

           F =   26.97 10-3 N

None of the charge are on the axis and therefore there are no forces on this axis.

             F = (2.7 10⁻² i ^ + 0j ^) N