Mechanical Energy Energy is the ability to do work
Mechanical Energy(ME) - enables an object to do work A. Kinetic Energy (E k ) - energy of motion B. Potential Energy(E p ) - stored energy
Gravitational Potential Energy An object lifted against the force of gravity has stored energy. UNIT= JOULE
Gravitational Potential Energy Only changes in potential energy can be measured E p = mgh m= massg= gravityh= height
As an object, such as a boulder, begins to move, it gains velocity. Gaining velocity increases the object’s kinetic energy.
Example Problem Legend has it that Isaac Newton “discovered” gravity when an apple fell from a tree and hit him in the head. If a 0.20 kg apple fell 7.0 m before hitting Newton, what was its change in E p during the fall?
Elastic Potential Energy If a spring of stiffness constant (k) is stretched an amount (d), the elastic potential energy stored in the spring is equal to 1/2 the the spring constant times the square of the distance stretched.