By: Theresa Rudnick
EDIM 508
Work-Energy
Theorem
Purpose: This presentation is intended to be a reference for students studying work, energy and how the two relate. It is currently set up to be presented, but can also serve as a tool for student-lead exploration. Students can come back to this presentation to focus on the two topics separately or explore how work causes changes in energy.
Standards Alignment:
KSDE Science Standard 2B: Physics,
Benchmark 2: The student will understand the conservation of mass and energy.
Benchmark 3: The student will understand the nature of the fundamental interactions of matter and energy.
The net work done on an object is equal to the object's change in energy
Kinetic Energy-
The ability to do work by virtue of motion
What is doing work on the objects in the video?
Is Dash doing work?
How much work is required to spin the cat?
Observe how the energy converts from kinetic to potential. What forces are causing this change?
Energy: the ability to do work.
This comes in many forms.
None. The force causing the cat to spin (centripetal force) is perpendicular to the cat's motion. Therefor, while movement occurs, no work has been done.
Yes. Dash is exerting a force
parallel
to his displacement.
What kinds of energies are present?
Work
Gravitational Potential Energy-
The ability to do work through virtue of position
in a gravitational field
is the product of a force exerted over a parallel displacement
W = F d
On the way down, the force of gravity does work to cause the man to convert gravitational energy into kinetic energy and then to spring potential energy.
The spring provides a restoring force that does work to convert the spring energy into kinetic and gravitational energy.
Gravity is the force responsible for the work done on the objects.
The objects begin with a large amount of graviational potentia energy. Gravity does work on the objects, converting this potential energy into kinetic energy as the velocity of the object(s) increase.
When the objects hit the ground, the surface provides a normal force that converts their kinetic energy into spring potential energy. The objects then do work to themselves and convert their spring potential energy into both kinetic and gravitational potential energy
Spring Potential Energy-
The ability to do work through virtue of compression/expansion of a spring
Citations
Pictures:
Gravitational Potential Energy retrieved September 17, 2012 from: http://image.wistatutor.com/content/work-energy/potential-energy-derivation.jpeg
Kinetic Energy retrieved September 17, 2012 from: http://annawrites.com/blog/wp-content/uploads/2011/01/kenetic-cougar.jpg
Spring Potential Energy retrieved September 17, 2012 from: http://www.ajdesigner.com/phphookeslaw/l_spring_potential_energy_equation.png
Videos:
“Energy of Oscillating Spring” retrieved Septemer 19, 2012 from:
“Incredibles- Track Race Scene” Retrieved September 17, 2012 from:
“More Balls Bouncing Video Reference” retrieved September 19, 2012 from:
“Spinning Cat” retrieved September 17, 2012 from: