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???
Yes, you are on the right track! The action-reaction pair of forces involved in the action of the arrector pili muscle causing the hairs on the arms to tilt upward when a person gets goosebumps can be described as follows:
1. Action: The arrector pili muscle contracts.
2. Reaction: The root sheath, which is connected to the arrector pili muscle, exerts an equal and opposite reactionary force in response to the contraction.
So, the action is the contraction of the arrector pili muscle, and the reaction is the force exerted by the root sheath in response to the contraction. These action-reaction forces cause the hairs on the arms to stand upright, creating the appearance of goosebumps.