work & energy unit 4 Flashcards
Forces perpendicular to the motion
CAN NEVER DO WORK - they are cos90 = 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 veloctiy
No change in kinetic energy = remains constant
Area under Force v. 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
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
Ug = mgdeltay
Elastic Potential Energy (Us)
Energy stored in elastic materials as the result of their stretching or compressing
Us = 1/2kx^2
Kinetic Energy
energy of motion
Translational Kinetic Energy
energy of a system due to the motion of the systems center of mass and velocity
KE=1/2mv
Mechanical Energy
Energy possessed by an object bc of 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
System taht exchanges energy with it surroundings through external forces/work
A single object system can only have
Kinetic Energy
“Work done against friction”
equal to the work done by friction and does not include any work to speed an object up
Work/total energy of a system
can be found by adding up the energies of the objects within the system
Work-energy principle (words) (ch7)
The net work done on an object is equal to the change in the object’s kinetic energy
(Translational) kinetic energy equation (ch7)
K=½mv²
What is the difference, other than the definition, between conservative forces such as mechanical energy and non conservative forces such as friction? (ch8)
The work done by a conservative force is recoverable
Work equation (no trig) (ch7)
W= F(vector)d(vector)
Work equation (trig) (ch7)
W=Fdcosθ
Scalar product of any two vectors A and B (ch7)
Scalar product of any two vectors A and B (ch7)
ABcosθ
Work-energy principle (equation) (ch7)
Wnet=∆K=½mv₁²-½mv₂²
What is potential energy? (ch8)
Energy associated with conservative forces that depend on the position or configuration of objects
What is a conservative force? (ch8)
(A force for which) the work done by it in moving an object from one position to another depends only on the two positions and NOT on the path taken (Path independent)
