Energy is the capacity to do work, which is a force applied over a distance. Therefore, the unit of energy is a Newton*meter or Joule.
The three types of energy this unit focuses on are Elastic Potential Energy (Us), Gravitational Potential energy (Ug) and Kinetic Energy (Ek).
The three types of energy this unit focuses on are Elastic Potential Energy (Us), Gravitational Potential energy (Ug) and Kinetic Energy (Ek).
Kinetic energy is the energy stored in motion, and can be modeled by Ke = 1/2mv^2, where m is the mass of the moving object and v is the objects velocity
https://www.youtube.com/watch?v=zDcf7eEaP0M
Gravitational Potential Energy is the energy stored in the height of an object, and the energy it can gain by falling. It can be modeled by Ug = mgh, where m is the mass of the object, g is the constant 9.8N'kg, and h is the change in height of the object.
https://www.youtube.com/watch?v=z3ujg_CkslI
Elastic potential energy is the energy stored by stretching a spring and can be modeled by Us = 1/2kx^2, where k is the spring constant in Newtons/meter, and x is the amount the spring is stretched.
https://www.youtube.com/watch?v=7ZnpsCV2GSY
Energy can be transferred into different types by work, but energy in the universe is always conserved. However, energy can flow in and out of a system of objects. For example, a block that slides to a stop on a table is an example of work, as the table applies a frictional force to the block over the distance it takes for the block to stop. If the system only consists of the block, it loses its kinetic energy as it slides to a stop. To solve problems like this, the definition of work is used, which is W = Fx, where F is a force working over a distance, x.
One way to visualize the transfer of energy is through LOL charts. A system's total initial energy is represented by a bar chart with amounts of each kind of energy. In the center is a circle where each object in the system is listed, and arrows pointing into or out of the circle represent the transfer of energy in or out of the system through work. On the second bar chart is the new amounts of different kinds of energy in the system. Below an LOL chart is typically a conservation of energy equation, where all of the initial energies are added up along with any work done to the system. This will be equal to the final energy of the system.
The area under a Force vs. Distance graph represents the energy transferred through working. For gravitational potential energy and the definition of work, this is a flatline relationship. However, the model for elastic potential energy is linear with the spring constant (k) being the slope. This makes sense because k is in Newtons/meter.
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