Work, Energy, and Power Flashcards
What is work?
- When a force acting on an object causes a displacement of the object
- transfer of energy
What is the unit of work?
Joule (Newton/meter)
What is the difference between negative and positive work?
Positive- force (parallel component) exerted parallel to displacement
Negative- force exerted (parallel component) not the same direction as d, hinders displacement
What is potential energy?
- Stored energy
- the amount of energy an object can potentially have
Where does the energy from work go?
- moves object (break from friction)
- heat block and atmosphere
- creates sound
What is gravitational potential energy?
-Energy stored in an object as a result of its height
What is the relationship between gravitational potential energy and height?
The higher an object is, the more potential energy it has
What is gravitational potential energy dependent on?
Mass and height of object
What must be assigned to determine the gravitational potential energy of an object?
A zero height position or reference level
What is elastic potential energy?
Energy stored in elastic materials (like spring) as a result of a stretching or compression
What does kx represent?
The force someone applies to a spring
What does -kx represent?
The force the spring applies to the object which is also applying a force on the spring
What does the law of conservation of energy state?
- The total amount of energy in the universe never changes.
- Energy is conserved; it can’t be created or destroyed, only transferred from one form to another.
Is work scalar or vector?
Scalar
Is spring force conservative?
Yes; you can recover the force exerted on the spring by releasing the spring
What does the conservation of mechanical energy state?
In any ISOLATED SYSTEM of objects interacting only through CONSERVATIVE FORCES, the total mechanical energy of the system remains the SAME at all times.
What is power?
Work/rate of energy transfer with time (average power)
What is kinetic energy?
Energy of motion
What is mechanical energy?
- the energy acquired by objects when work is done on it
- can be either kinetic or mechanical
Why was the joule names after James Prescott Joule?
James Prescott Joule was credited for discovering the law of conservation of energy
Who invented the joule?
James Prescott Joule
Where do human beings get energy to move?
Food
What is the unit for power?
- The rate of energy transfer over time
- the amount of work done over time
What is the speed needed for a projectile to leave the earth’s atmosphere?
about 11 km/s
What the equation for stable equilibrium?
-change in potential energy/change in displacement
What are conservative forces?
- forces that can be easily recovered
- if the work a force does moving an object between two objects is the same no matter what path is taken
What are nonconservative forces?
forces that cannot be easily recovered
What does the work-energy theorem relate?
work with energy (W= change in kinetic energy)
