Question

Two balloons having the same charge of 1.2 × 10-6 coulombs each are kept 5.0 × 10-1 meters apart. What is the magnitude of the repulsive force between them? (k = 9.0 × 109 newton·meter2/coulombs2)

1.2 × 10-2 newtons
3.2 × 10-3 newtons
6.5 × 10-3 newtons
3.0 × 10-4 newtons
5.2 × 10-2 newtons

Answer 1

For plato users: Option E. 5.2 x 10^-2 is correct.

Answer 2

The answer is 5.2 × 10-2 newtons.

To calculate this, we will use Coulomb's Law:
F =
`(k * Q_(1) * Q_(2) )/( r^(2) )`
where F is repulcive force, k is constant, Q is charge, r is distance between charges.

If:

`Q_(1)` =
`Q_(2)` = 1.2 ×
`10^(-6)` C²
r = 5.0 ×
`10^(-1)` C²
k = 5.0 ×
`10^(9)`
`(N*m^(2) )/( C^(2) )`

Then:

`F = (5.0* 10^(-1) (N* m^(2) )/( C^(2)) * 1.2 * 10^(-6) C * 1.2 * 10^(-6) C )/((5.0* 10^(-1) m)^(2))`
⇒
`F= (9 * 1.2 * 1.2 * 10^(-3) N )/(25* 10^(1) )`
⇒
`F = (12.96* 10^(-2) )/(25) N`
⇒
`F = 5.2 N`