Chapter 4 Sections 2 and 3 Flashcards
energy is the ability to…
cause change/ do work
a system is anything around which you can ______
imagine a boundary
What happens when one system does work on another system
energy is transferred from the 1st to the 2nd
What are the 4 different forms of energy (2 extra)
chemical
mechanical
electrical
radiant
(sound)
(thermal)
what is chemical energy
anything that can produce energy
what is mechanical energy
something moving
what is radiant energy
light
is energy from the sun and energy from the food you eat the same
yes but different forms
kinetic energy is the energy due to _____
motion
what is the formula and unit for kinetic energy
KE = 1/2 m v^2
joules
what are the 2 variables you must know to calculate kinetic energy
mass
velocity
potential energy is energy that is _____ due to the …
stored
interactions between objects
other names for potential energy
stored energy
energy at rest
energy of position
elastic potential energy is the energy that is _____ by _____ an object
stored
compressing or stretching
chemical potential energy is energy that is due to _____
chemical bonds
gasoline and the food you eat have stored energy, where is this stored energy?
chemical bonds between atoms
gravitational potential energy is energy of _____ and _____
position
mass
what is the formula for gravitational potential energy
GPE = m g h
what three variables must you know to calculate GPE
mass
gravity
height (above ground)
can a system have kinetic energy and potential energy at the same time
yes
if something in the system is moving
The different molecules that make up the air in a room have, on average, the same kinetic energy. How does the speed of the different molecules that make up the air depend on their masses?
in order for their KE to be equal, the smaller molecules (less mass) must travel faster than the larger molecules (more mass)
the law of conservation of energy states that energy…
cannot be created or destroyed, but energy can change into other forms
mechanical energy is the…
sum of the kinetic energy and potential energy of the objects in a system
What is the formula for mechanical energy
ME = KE + PE
when an apple falls from a tree what does it lose and what does it gain
gravitational potential force
kinetic energy
mechanical energy includes what kind of energy
kinetic energy and potential energy
can potential energy be converted into kinetic energy
yes
if some potential energy in a system is converted to kinetic energy, would the amount of mechanical energy remain the same
yes
if mechanical energy is conserved, why does a person on a swing en=ventually come to a stop?
the energy from the swinging gets transferred due to friction
ex. into sound
a lightbulb is a device that transforms _____ energy into _____ energy
electrical
radiant
fuel stores energy in the form of _____ potential energy
chemical
a car engine transforms chemical potential energy into _____ energy and then into _____ energy.
also _____ energy
thermal
mechanical
sound
every green plant converts _____ energy into _____ energy
radiant
chemical potential
power is the rate at which…
energy is converted
energy from food is often measured in
calories
every gram of fat you eat supplies the body with about __ calories
10
every gram of protein you eat supplies the body with about __ calories
5
every gram of carbohydrate you eat supplies the body with about __ calories
5
what is the formula for power
P = E/t or w/t (Joule/second)
the standard unit used to measure power is the _____
watt (W)
What are the other units for power and when are they used
British thermal units (Btu): energy of heater, hot water heater, or AC
horsepower (HP): the power an engine produces
1Btu = _____ watts
1055
1 HP = _____ watts
746
