title: Euler/RK4 python for Orbite simulation
body: <p>I started a code for an orbite simulation for 8 planetes (with the sun in (0,0))
  I got accelerations on X and Y, now I need to use them to get the speed on X and Y, using Euler first, then RK4, and I got stuck, I don't know where to start. Here's my code:</p>
  
  <p><img src="https://i.stack.imgur.com/apZjO.png" alt="enter image description here"></p>
  
  <p><img src="https://i.stack.imgur.com/aRvIf.png" alt="enter image description here"></p>