Algodoo

It's a brushed electric motor. Very basic, drag to start, and it'll make a few revolutions. It isn't perfect, and I hope to make it worthy of powering a vehicle.

onCollide = (e)=>{ e.other.attraction = x } to switch attraction, X is set to desired variable. you can also use e.other.color = [x, x, x, x] to set desired color for different states.