Answer:
r = 0.05 m = 5 cm
Explanation:
Applying ampere's law to the wire, we get:

where,
r = distance of point P from wire = ?
μ₀ = permeability of free space = 4π x 10⁻⁷ N/A²
I = current = 2 A
B = Magnetic Field = 8 μT = 8 x 10⁻⁶ T
Therefore,

<u>r = 0.05 m = 5 cm</u>
A scientist would write that number as 1.49 x 10⁸ kilometers .
(Or, if the scientist is in France or the UK, he might write it as 1.49 x 10⁸ kilometres .)
Kinetic energy, KE, is modeled by the formula

, where m is the mass in kg and v is the velocity in m/s.
In this scenario, mass and one-half are constant but the velocity changes.
You can see that by squaring twice the velocity, that is equal to four times the original KE. Therefore, the answer is 4k.