Question

Two 3.0kg masses are 1.0m apart on a frictionless table. Each has 1.0?C of charge.

Part A

What is the magnitude of the electric force on one of the masses?

Part B

What is the initial acceleration of each mass if they are released and allowed to move?

Answer 1

Mass, m₁ = m₂ = m = 3 kg

Separation between them, r = 1 m

Charge on them, q₁ = q₂ = q = 1 * 10^-6 C

Part A

Magnitude of the electric force on one of them is,

F = k q * q / r²                                          where k = 9 * 10⁹ Nm² / C² is Coulomb's force constant

F = 9 * 10⁹ * 1 * 10^-6 * 1 * 10^-6 / 1

F = 9 * 10^-3 N

Part B

Force (F) = mass (m) * acceleration (a)

a = F / m = 9 * 10^-3 / 3

a = 3 * 10^-3 m/s²