A space probe 2.0 * 1010 m from a star measures the total intensity of electromagnetic radiation from the star to be 5.0 * 103 W>m2 . If the star radiates uniformly in all directions, what is its total average power output

 P = 1.0 10¹⁴ W

Explanation:

Radiation intensity is the power radiated by unit area,

        I = P / A

As the star radiates uniformly, the radiation expands into a sphere, the area of this sphere is

       A = 4π R²

Let's replace

     P = I (4π R²)

Let's calculate the power

    P = 5.0 10³  2.0 10¹⁰

   P = 1.0 10¹⁴ W

This is the power radiated by the star

there are no contact forces mentioned on the list of choices that you've provided.