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AP Physics I: Unit 4, Work and Energy Principles

Terms in this set (22)

Forces that are perpendicular to the motion...
CAN NEVER DO WORK. They are cos90 which = 0
Worknet =
Change in kinetic energy
Direction of the displacement is in the direction of the force..
Cos0 = 1
Direction of the displacement is in the opposing direction of the force..
Cos180 = -1
Constant terminal velocity
No change in kinetic energy = remains constant
The area under a Force vs Position graph..
..equals the work done
Law of Conservation of Energy
The law that states that energy cannot be created or destroyed but can be changed from one form to another.
Energy is
the ability to do work
Power
Measures the rate at which someone or something does work.
Conservation Interaction
The force can restore the energy it removes as it does work BACK into the object independent of the path it takes..
ex: Gravitational and Elastic Potential Energy
Energy that isn't conserved..
Thermal
Potential Energy
The stored energy of position by an object
Gravitational Potential Energy (Ug)
Energy stored in an object as the result of its vertical position or height.
Elastic Potential Energy (Us)
Energy stored in elastic materials as the result of their stretching or compressing.
Kinetic Energy
The energy of motion.
Translational Kinetic Energy
The energy of a system due to the motion of the systems center of mass and velocity
Mechanical Energy
Energy that is posessed by an object due to its position or due to its motion (ability to do work). It can be either kinetic or potential.
Closed Energy System
A conserved, isolated system in which no energy from outside the system can get in and no energy from the inside can get out.

Internal forces do not affect the conservation.
Open Energy System
A system that exchanges energy with its surroundings through external forces, or work.
A single object system can only have...
Kinetic Energy
"Work done against friction"
It is equal to the work done by friction and does not include any work to speed an object up.
Work or total energy of a system
can be found by adding up the energies of the objects within the system.
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