Can you recall what centrifugal force is, and think why a molecule with higher mass/density would sediment faster?

Centrifugal force is a type of force that acts on any object moving in a circular path. It is directed outward from the center of rotation. The term "centrifugal" comes from Latin, meaning "fleeing from the center". It's often experienced in a rotating system, for example, when you're turning a corner in your car, the force that pushes you to the side, that's centrifugal force.

Now, let's consider a molecule in a centrifuge. The centrifuge works by spinning a sample around in a circle. This causes denser substances to separate out along the radial direction (the direction along the radius of the circle). The denser substances, or those with a higher mass, experience a greater centrifugal force and thus move or sediment to the bottom of the tube faster.

This is because the centrifugal force acting on an object in a centrifuge is dependent on the mass of the object, the speed of rotation, and the distance of the object from the center of rotation. So, a molecule with a higher mass/density will experience a greater centrifugal force and will sediment faster.