Work, Energy, Power and Efficiency Flashcards
What is mass?
Quantity of matter.
“_____” is any influence that attempts to cause a change in the relative motion of an object.
Force.
What is an object’s “weight”?
The amount of force required to equalize the force of gravity on the object’s mass.
At sea level what is the force of earth’s gravity?
9.81 N/kg
What are the four known forces?
- Gravitational
- Electromagnetic
- Strong nuclear
- Weak nuclear
What is work?
The application of a force to an object to change it’s motion.
If there is no change in motion, no work is done.
“_____” is the capacity to do work.
Energy.
Energy exists in two basic forms, what are they?
- Potential energy
- Kinetic energy.
What is the unit of measurement for energy and work?
The joule.
What is power?
What is it measured in?
The rate of doing work.
Watts or joules per second.
What is one horsepower in watts?
746 watts
What unit is electrical energy typically measured in?
Kilowatt-hour (equal to 3.6 Megajoules)
How would one find the efficiency percentage of a circuit?
Divide the output power at the load over the input power at the source and multiply by 100.
What is line loss?
Power lost as heat in a circuit’s conductors.
What are some losses that exist in a motor?
- Friction loss
- Windage loss
- Line loss in the windings
- Iron losses (hysterisis and eddy currents)
