The total work done by the electric field on the charge is given by the scalar product between the electric force acting on the charge and the displacement of the charge:

where the force is F=qE, d=0.556 and

. Using the value of q and E given by the problem, we find
Answer:
N = 23.4 N
Explanation:
After reading that long sentence, let's solve the question
The contact force is the so-called normal in this case we can find it by writing the translational equilibrium equation for the y axis
N - w₁ -w₂ =
N = m₁ g + m₂ g
N = g (m₁ + m₂)
let's calculate
N = 9.8 (0.760 + 1.630)
N = 23.4 N
This is the force of the support of the two blocks on the surface.
Answer:
2.16×10⁻⁶ N
Explanation:
Applying,
F = kqq'/r² (coulomb's Law)....................... Equation 1
Where F = electrostatic force, k = coulomb's constant, q = charge on the styrofoam, q' = charge on the grain of salt, r = distance between the charges.
From the question,
Given: q = 0.002 mC = 2.0×10⁻⁶ C, q' = 0.03 nC = 3.0×10⁻¹¹ C, r = 0.5 m
Constant: k = 8.99×10⁹ Nm²/C²
Substitute these values into equation 1
F = (2.0×10⁻⁶)(3.0×10⁻¹¹)(8.99×10⁹)/0.5²
F = 2.16×10⁻⁶ N