# BIO 158- Chapter 4

 What is work? It is the means by which energy is transferred from one object or system to another.U = F(delta d)The unit of measurement is the Joule, J What is energy? In mechanics, energy is defined as the ability to do work.Energy comes in many forms: heat, light, sound, chemical, mechanical Kinetic Energy Energy due to motionA moving object has the ability to do work because of its motion.The unit of measurement is the Joule, JKE =1/2mv2 Potential Energy Energy due to motionTwo types: Gravitational and Strain Energy Gravitational Potential Energy (GPE) Potential energy due to an object's position relative to the earth.GPE of an object is related to its mass(m) and the height of the object (h)Unit of measurement is the Joule, JGPE = -mgh Strain Potential Energy Due to the deformation of an object.SPE of an object is related to its material properties (k) and the amount of deformation (x)The unit of measurement is the Joule, JSPE = 1/2kx2 Work-Energy Relationship The unit of measure for work and energy is Joules.Work is the means by which energy is transferred from one object to another object. Demonstrating the Work-Energy Relationship The work done equals the change in gravitational potential energy. Work-Energy Principle The work done by external forces (other than weight) acting on an object causes a change in energy of the object.U = delta EU = deltaKE + deltaGPE +deltaSPE Conservation of Mechanical Energy When is Mechanical Energy Conserved? When no external forces, other than weight, act on the body.If there are no external forces, other than weight, acting on the body, NO WORK is done.If no work is done, the total mechanical energy of the object is conserved (i.e., it cannot be changed; it remains constant) Conservation of Mechanical Energy (2) continued... Thus, it can be used to analyze situations in which no work is done. For instance, in the pole fault, the vaulter does no work during the vault itself (i.e., once he or she leaves the ground)(KE + GPE + SPE) initial = (KE + GPE + SPE) final Power The rate of doing work or how much work is done in a specific amount of time. It can also be thought of as how quickly or slowly work is done. The unit of measurement is the Watt, WPower can also be defined as... average force times average velocity (Fv) along the line of action of that force. Authoraab100687 ID80473 Card SetBIO 158- Chapter 4 DescriptionExplaining the Causes of Motion without Newton Updated2011-04-18T23:23:25Z Show Answers