What are some characteristics of mechanical weathering?

Summarize possible ways in which phases of matter could combine to form a solution.

The human eye contains a molecule called 11-cis-retinal that changes shape when struck with light of sufficient energy. the change in shape triggers a series of events that results in an electrical signal being sent to the brain that results in vision. the minimum energy required to change the conformation of 11-cis-retinal within the eye is about 164 kj/mol.

Is a pencil falling to the floor anon contact force, a force, or a contact force