Unit 10- Energy, Work, Simple Machines Flashcards
Example of energy is …
- Tree branches swaying in the wind
What is energy?
The ability to do work
a) not the same as matter doesn’t occupy space or have mass
b) can only be described by what it does
c) can be measured but only effects can be seen
What’s the source of mechanical energy and examples?
Source - moving parts
Examples - muscles, machines, wind, rivers
What’s the source of Chemical Energy and examples?
Source - molecules
Examples - fossil fuels, FOOD, batteries
What’s the source of Solar Energy and examples
Source - Sun
Examples - heat, light, ultraviolet radiation
What’s the source of electrical energy and example
Source - electrons
Examples - lighting, electrical currents
What’s the source of heat energy and examples?
Source - movement of particles in a substance (friction)
Examples - rubbing hands together to make them warm
What’s the source of Nuclear Energy and examples
Source - atomic nuclei ( protons or neutrons being shot out of unstable isotopes)
Examples - uranium
What’s the source of Geothermal Energy and examples?
Source - heat from inside the earth
Examples - hot springs, geysers
What’s the source of Sound Energy and examples?
Source - vibrations of matter
Examples - thunder, piano, guitar, singing, Amy
What’s the source of Light Energy and examples
Source - waves of energy bundles, photons
Examples - sun, light bulb
What’s renewable energy?
Energy that’s for all practical purposes everlasting
Sun, wind, falling water, tides, geothermal biomass
Energy transformations
Energy is being transformed in everyday activities from one form to another
Examples of energy transformation
Running a mile in gym - chemical to mechanical
Kinetic and Potential energy
All forms exist as either kinetic or potential
Potential energy and examples
Energy of position, higher position is greater potential energy, a resting object has potential energy
Examples - parked car, battery
WORK
Occurs when a force causes an object to move in the direction the force is applied
a) work involves motion not just effort
b) only happens when force on a object is in the same direction as objects motion
c) if force is at angle only part of the force that’s in the same direction as the motion does work
Formula for work
W=FxD
work= force x distance
W= (m•a) •d
Measured in Joules
Work and distance
Distance in the work equation is the distance an object moves while the force is being applied
Work and kinetic energy
Doing work on an object increases kinetic energy
POWER
How quickly work is done
Power =work \time
Units- watts
Energy Transfer
Amount of work done is the amount of energy transfer and can be expressed as Power = energy transfer/ time
Machine
Device that makes work easier
a) change the way work is done
b) not change the amount o work done
Input force
Force u exert on a machine
Output force
The resisting force or the work a machine does to move an object over some distance
Mechanical Advantage
The number of times the input force is multiplied by a machine
Mechanical force= output force / input force
