Describe what happens when a muscle contracts

According to the internet,

During a concentric contraction, a muscle is stimulated to contract according to the sliding filament theory. This occurs throughout the length of the muscle, generating a force at the origin and insertion, causing the muscle to shorten and changing the angle of the joint.

the gravitational force on an object increase as the mass of an object also, im not going to report you, but this question should be under the science category, not health