Work and Enerygy Flashcards
Is defined as the product of the force component that is parallel to an object’s motion and the distance that the object is moved
Work
Is done by a force on a system
Mechanical work
Work is a scalar and can be positive, negative, or zero
True or False
True
The SI unit of work and energy is
Joule (J)
For mechanical work the units __ may be used
N*M
Any kind of force cannot do work
True or False
False
Not every force on an object will do work
True or False
True
A force-distance graph is not helpful for a varying force
True or False
False
The proportionality constant k is called
spring constant
Work done on a spring by an external force is always positive
True or False
True
Ideal strings have mass and the value of k for the spring is not constant throughout its range of displacement
False
Any force that is proportional to the displacement of a system from an equilibrium position is called
Hooke’s Law force
The spring force is opposite to the direction of displacements from its equilibrium position caused by an external force
True or False
True
The time rate of work done on a system by a force
Power
The rate at which a force does work at any instant
Instantaneous Power
Power is a vector quantity that is proportional to the force acting on a system and speed of a system
False
The SI unit of power
Watt (W)
The mechanical energy associated with motion
Kinetic Energy
States that the total work done on a system by all external forces acting on it is equal to the change in the system’s kinetic energy
Work-Energy Theorem
All work changes kinetic energy
False
Is energy due to an object’s condition or position relative to some reference point assumed to have zero potential energy
Potential Energy
The SI unit of Kinetic and Potential Energy
Joule (J)
Only forces that are conservative forces have their own potential energy
True or False
True
Can store work energy as some form of mechanical potential energy
Conservative forces
Which is not an example of conservative forces
The gravitation force
any central force
any Hooke’s law force
fluid drag
Fluid drag
Convert work energy into mechanical unstable forms of energy
Non-conservative forces
Which is not an example of non-conservative forces
kinetic frictional force
internal resistance
fluid drag
the gravitational force
the gravitational force
The work required to move these masses apart against the force of gravity is equal to their
gravitational potential energy
The work of one force on a system often causes a change in potential energy with respect to another force also acting on a system
True or False
True
Its potential energy per kilogram at a specified distance r from a zero reference distance
gravitational potential
Gravitational potential energy is negative for any measurable separation distance
True or False
True
Can be produced with respect to spring-like (elastic) forces, which are conservative forces
Elastic potential energy
The work by ___ on a system is equal to the change of the sum of kinetic and potential energies of the system
Nonconservative forces
Is the sum of a system’s kinetic and potential energies:
Total mechanical energies (E)
The work accomplished by all nonconservative forces on a system during a certain process is equal to the change of total mechanical energy of a system
True or False
True
When only conservative forces are acting on a system, the increase of kinetic energy is equal to the loss of mechanical potential energy and vise versa. This is the principle of
Conservation of mechanical energy
