Hairs on the arms are tilted upward when a person gets goose bumps. The contracting muscle is called arrector pili and connects to the epidermis and the root sheath. Can you identify an action-reaction pair of forces that is involved in its action?
My ans:
I think the contractor muscle and sheath cause the action-reaction force, where the contractor muscle exerts a force on the sheath and the sheath exerts an equal force back???