Matter JS - Physics - How to define a heavy element, hard to be moved by small ones

I've been struggling with Matter JS physics, trying to get them right. I have 2 elements:

 Matter.Bodies.rectangle(400, 400, 113, 66, {
    frictionAir: 1,
    friction: 1,
    density: 0.5,
    restitution: 0
})
Matter.Bodies.circle(0, 0, 5, {
    friction: 0.05,
    frictionAir: 0.05,
    density: 0.001,
    restitution: 0.5
})

According to the documentation, the first one should be heavy and strong. But adding a force of only 0.004 to the small one, I manage to move the big object quite a lot. I tried various numbers and nothing works.

I basically want to have an object that is very hard to be moved by small ones but still be able to move it by adding force to it.

Any help would be appreciated!