Typically an RN like Jolene will walk several miles over the course of a 12 hour shift on the MED floor. When Jolene wants to change her to start, stop, speed up, slow down, or change direction she must always interact with another object. Usually the other object is the floor, but sometimes she grabs a handrail to help her change direction around a corner. The process of generating and controlling motion is known as locomotion. In this unit we will examine why she needs to interact with other objects in order to perform locomotion, as well as the size, direction, and duration of the forces she experiences during those interactions. Generally we call those interactions collisions, so in essence we will be analyzing collision forces. The associated lab will guide us through an analysis of forces on the body during a vehicle collision and how crumple zones are designed to reduce those forces. This unit will introduce the required concepts, including Momentum Conservation and Newton’s Laws of Motion. The learner outcomes for this unit are listed below, and below that are some related key terms to watch out for as you complete the chapter.
- Apply the Law of Conservation of Momentum to explain how locomotion is achieved.
- Apply the Law of Conservation of Momentum to analyze collisions.
- Apply the Impulse-Momentum Theorem to analyze collision forces.
- Apply Newton’s Laws of motion to analyze predict the motion of systems subjected to external forces.]
Key Terms and Concepts
a quantity of speed with a defined direction, the change in speed per unit time, the slope of the position vs. time graph
A collection of objects to be analyzed. Forces between the objects are considered internal forces, while forces applied by objects outside the system are considered external forces.
a system for which neither thermal energy or particles are allowed to leave or enter.
mass multiplied by velocity
The total momentum of an isolated system cannot change.
the change in momentum experienced by system is equal to the net force on the system multiplied by the amount of time that force is applied
An object will not change it's motion unless acted upon by an external force.
The net force on a system is equal to the system mass multiplied by the acceleration
If object A exerts a force on object B, then object B also exerts an equal and opposite force on object A for the same amount of time