Question

A SI unit used to measure force, equal to less than one-quarter of a pound, is the what

Answer 1

The SI unit of force is the Newton.

1 newton is the force that accelerates a 1 kilogram mass
at the rate of 1 meter per second².

1 pound of force is equivalent to roughly  4.448 newtons.

(1 newton is equivalent to roughly  0.225  pounds of force.)