A proton with mass 1.67×10⁻²⁷ kg is propelled at an initial speed of 3.00×10⁵ m/s directly toward a uranium nucleus 5.00 m away. The proton is repelled by the uranium nucleus with a force of magnitude f = k/x², where x is the separation between the two objects and k = 2.12×10⁻²⁶ N∙m². Assume that the uranium nucleus remains at rest. What is the magnitude of the force exerted on the proton when it is 5.00 m away from the uranium nucleus?
a) 3.40×10⁻¹⁰ N
b) 1.35×10⁻¹¹ N
c) 4.24×10⁻¹⁰ N
d) 1.69×10⁻¹¹ N