UNIT 7: Work, Energy and Power (12 Days)

Unit 7

Work, Energy and Power

UNIT 7: Work, Energy and Power (12 Days)

Enduring Understanding: Physics work happens when a force causes an object to displace. The work done is force (in the direction of motion) times the displacement. Energy is needed to do work. Work and energy are measured in joules. Power is the rate of doing work; power is the rate of any energy transfer. Power is measured in watts. Kinetic energy is energy of motion. Potential energy is energy stored and ready to do work due to its position. Gravitational Potential energy is due to position in a gravitational field; elastic energy is energy stored in a flexible object. Mechanical energy is potential energy and kinetic energy. Many energy exchanges obey the Law of conservation of Mechanical Energy; they retain all of their mechanical energy. Inelastic collisions loose mechanical energy; elastic collisions do not loose mechanical energy.
Essential Questions:
What is work?
What are the different forms of mechanical energy.
What does the graph of potential energy plus kinetic energy generally look like?
What is the Work-Energy Theorem?
What is the Law of Conservation of Energy? / SC.912.P.10.3 Compare and contrast work and power qualitatively and quantitatively
·  Students will define and compute work. W=Fd W=Fdcosθ
·  Students will define and compute power. P=Wt
·  Students will recognize the SI units for work and power.
SC.912.P.10.1 Differentiate among the various forms of energy and recognize that they can be transformed from one form to others.
·  Students will define and compute kinetic energy. KE=12mv2
·  Students will define and compute gravitational potential energy. PE=mgh
·  Students will define elastic potential energy.
·  Students will define and compute mechanical energy. ME=PE+KE
·  Students will recognize the SI units for energy.
SC.912.P.10.6 Create and interpret potential energy diagrams, for example: motion of a pendulum.
·  Students will recognize the graphic sum of potential and kinetic energy shows constant mechanical energy.
SC.912.P.10.2 Explore the Law of Conservation of Energy by differentiating among open, closed, and isolated systems and explain that the total energy in an isolated system is a conserved quantity.
·  Students will apply the Work-Energy Theorem. Wnet= ΔKE
·  Students will apply the Law of Conservation of Energy.
KEbefore+PEbefore=KEafter+PEafter
·  Students will differentiate between Elastic and Inelastic collisions.