pls help me with this

Question

If a planet was located approximately 23 thousand light-years from the center of a galaxy and orbits that center once every 273 million years, how fast is the planet traveling around the galaxy in km/hr?

Answer 1

2 sigfigs, so we'll round to 4.

C = πd, so if d/2=23₃ ly and ly=9.461₁₂ km, C = 1.368₂₁ km

To get the number of hours, you need a chain. 273 million years * 365.25 days/year * 24 hours/day. Years and days cancel, and you get 2.393₁₂.

Now divide 1.368₂₁ / 2.393₁₂ to get 5.716₈

With proper rounding to 2 sigfigs, we get 5.7₈ or 570 million km per hour.