Question

If the only force exerted on a star far from the center of the Galaxy (r = 7.40 ✕ 1020 m) is the gravitational force exerted by the ordinary matter (Mord = 1.90 ✕ 1041 kg), find the speed of the star. Assume a circular orbit and assume all the Galaxy's matter is concentrated at the center.

Answer 1

Answer:

The value is  $v = 1.309*10^{5}\ m/s$

Explanation:

The radius is $r = 7.40 *10^{20} \ m$

The mass of the ordinary matter is $M_{rod} = 1.90 *10^{41}\ kg$

Generally the speed of the star is mathematically represented as

         $v = \sqrt{\frac{G * M}{r} }$

Here G is the gravitational constant with a value

        $G = 6.67384 * 10^{-11}$

So

      $v = \sqrt{\frac{6.67384 * 10^{-11} * 1.90 *10^{41}}{7.40 *10^{20}} }$

=>    $v = 1.309*10^{5}\ m/s$