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Energy Exam

Terms in this set (64)

Energy
the ability to do work
Joules (J)
unit of energy
What happens to energy when work is done
transferred or transformed
When can energy be observed
during transferring
Law of Conservation of Energy
energy cannot be created or destroyed
Five main types of energy
mechanical, electromagnetic, heat, chemical, and nuclear
Relationship between mass and energy
mass and energy are always conserved and can be transferred
Potential Energy
the stored energy resulting from the relative positions of objects in a system
Types of Potential Energy
Elastic Potential Energy and Gravitational Potential Energy
Elastic Potential Energy
is the energy stored in any type of stretched or compressed elastic material
Gravitational Potential Energy
is the energy in any system or two or more objects separated by a distance, and it results from the gravitational attraction between the objects
PE=mgh
formula to calculate Potential Energy
Kinetic Energy
the energy of a moving object due to its motion
KE=1/2mv^2
formula to calculate Kinetic Energy
Why is velocity important to the calculation of Kinetic Energy
velocity is squared in the formula, a small increase in speed produces a large increase
Why is Mechanical Energy so often associated with Potential and Kinetic Energy
Potential and Kinetic Energy are related to something moving
Mechanical Energy
energy associated with motion
Example of Mechanical Energy
a kite flying, a man playing a violin, a man swinging a bat
Example of Mechanical Energy being converted or transformed to some other type of energy
- (transformed) when a ball bounces, some of its mechanical energy is changed to heat energy because of friction
- (converted) a gas motor starts with chemical energy converting to mechanical energy
-(converted) an electric motor starts with electromagnetic energy changing to mechanical and heat energy
Electromagnetic Energy
electricity results from the flow of charged particles through wires or other conducting materials
Example of Electromagnetic Energy
lightening, rainbow, power lines, a women blow drying her hair
Example of Electromagnetic Energy being converted or transformed to some other type of energy
-(transformed) an electric motor in a fan can make the blades turn, changing electric energy to mechanical energy
-(transformed) a toaster starts with electromagnetic energy and changes to heat energy
-(transformed) a light bulb starts with electromagnetic energy and changes to heat energy
-(transformed) a lamp starts with electromagnetic energy and changes to heat energy
Heat Energy
heat energy is a result of the internal motion of particles of matter
Example of Heat Energy
burning candle, the sun, lightening, woman blow drying her hair
Example of some other type of energy being converted or transformed into Heat Energy
some materials can become so hot that they glow, changing heat energy to light energy
-(converted) electric motor starts with electromagnetic energy changing to heat and mechanical energy
-(converted) toaster starts with electromagnetic energy and changes to heat energy
-(converted) light bulb starts with electromagnetic energy and changing to heat and light energy
-(converted) lamp starts with electromagnetic energy and changing to heat and light energy
-(converted) chemical energy converting to heat and light energy
Chemical Energy
energy that bonds atoms or ions together
Example of Chemical Energy
cooked food
Example of Chemical Energy being converted or transformed to some other type of energy
-(transformed) when a match burns, the release of stored chemical energy from the match head changes to light energy and heat energy
-(transformed) kerosene lantern starts with chemical energy and changes to light and heat energy
Nuclear Energy
contained in the nucleus of atoms
Example of Nuclear Energy
the sun burning, an ex-ray
Example of Nuclear Energy being converted or transformed to some other type of energy
-(transformed) nuclear energy on the sun is changed to heat and light energy which we feel and see on the Earth
Specific Heat
the number of calories required to raise the temperature of 1g of substance 1C
Water's specific heat
water has a high specific heat
Methods of Heat Transfer
Conduction, Convection, Radiation
Conduction
an exchange of energy between microscopic particles by collision
Example of Conduction
a pan on a heated stove coil
Convection
energy transferred by the movement of a substance
Example of Convection
a hand held over a flame is warmed
Two types of Convection
Natural Convection and Forced Convection
Natural Convection
when the movement results from differences in density
Forced Convection
when the movement is forced by a fan or a pump
Radiation
all objects radiate energy continuously in the form of electromagnetic waves due to thermal vibrations of the molecules
Example of Radiation
radiation is the only way we can get our warmth from the Sun through the vacuum of space
Calorie
measure of heat
Why do oily foods generally have more calories than watery foods
oily foods burn more readily because of all the energy
When is energy present
can be present in an object or system when nothing is moving at all
What does Gravitational Potential Energy depends on
mass and height
When two objects are of equal distance from the ground which one has greater Gravitational Potential Energy
the one with the more mass
When two objects have the same mass at different heights from the ground which one has the greater Gravitational Potential Energy
the one farthest from the ground
Newtons (N)
the unit of measurement when mass and gravity is the weight of the object
What is the force on an object due to gravity
mass and gravity
The formula for Potential Energy is also
force times distance (the same equation to calculate work)
Kinetic Energy depends on
speed more than mass
Why would the total energy in a system increase
due to energy that enters the system from an external source
System
the area or number of objects studied are kept small
An object that is difficult to warm up has what kind of specific heat
high specific heat
An object that is easy to warm up has what kind of specific heat
low specific heat
How can you view Conduction
on an atomic scale
How is the energy exchanged between particles in a Conduction
when less energetic particles gain energy by colliding with more energetic particles
The rate of Conduction depends on what
the characteristics of the substance
Example of a good conductor
metals
When does Conduction occur
only when there is a difference in temperature between two parts of the conducting medium
When food has low calories what is its specific heat
its specific heat is low
Food with high calories burn at what specific heat
high heat
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