The Sun's mass is 2.0 × 10³⁰ kg and the Earth's is 6.0 × 10²⁴ kg…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
The Sun's mass is and the Earth's is . Their centres are apart. How far from the Sun's centre is their centre of mass? The Sun's radius is : is the point inside the Sun?
Need a reminder? The key ideaShow
The centre of mass is the mass-weighted average position: , and the same for and . For a continuous body, . A hole can be treated as a negative mass.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Plan. Origin at the Sun, so only the Earth's term survives.
Step 1. .
Answer: About from the Sun's centre, deep inside the Sun.
Check. is tiny next to the Sun's radius, . The Earth barely makes the Sun wobble.
Watch out. The Earth's mass is so small that adding it to the Sun's in the bottom changes nothing you can see.
Discussion (0)
Log in to join the discussion.
Loading…