Question

Two identical particles, each with a charge of 2.0 × 10⁻⁴ C and mass of 10 g, are kept at a separation of 10 cm and then released. What would be the speed of the particles when the separation becomes large?

Answer 1

Given:
Magnitude of charges, q  = 2.0 × 10⁻⁴ C
Mass of particles, m = 10 g = 0.01 kg
Separation between the charges, r = 10 cm = 0.1 m
Force of repulsion,

Δ P.E = Δ K.E

`("Kq"^2)/"r"`

= `2 xx 1/2 "mv"^2`

v = `sqrt(("Kq"^2)/("rm"))`

= `sqrt((9 xx 10^9 xx 4 xx 10^(-8))/(10 xx 10^(-2) xx 10 xx 10^(-3)))`

= 600 m/s