Unit 7 Flashcards
What’s the formula for power?
W=J/T
What is power?
The amount if work done in a specific period of time.
How many joules of work does it take in 60 seconds to produce 100 watts?
6,000 joules
How many watts is one kilowatt?
1,000
What is one kilowatt-hour?
The energy used by something at 1,000 watts in one hour.
What’s efficiency?
The amount of useful work done by the machine compared to how much work it took to run the machine.
What’s the formula for efficiency?
Work output / work input * 100%
What’s a machine?
Device that makes work easier by changing the size or direction of a force.
What’s work output?
The amount if useful work done by the machine.
What’s work input?
The amount of work put in to make the machine work.
What is heat considered in mechanical systems?
A waste of energy
What’s the biggest contributing factor to the inefficiency of machines?
Friction.
What are the 6 simple machines?
Inclined plane, lever, pulley, wedge, wheel and axle, and screw.
What’s a compound machine?
A combination of more than one simple machine.
What’s friction?
The resistance of two objects in motion rubbing against each other.
