Energy- Energy Flashcards
10 stores of energy are c______, t______, k______, g____________ p_________, e_______ p_________, n______, s____, l____, e_______ and m________.
10 stores of energy are chemical, thermal, kinetic, gravitational potential, elastic potential, nuclear, sound, light, electric and magnetic.
The unit of energy is ______ (_)
The unit of energy is Joules (J)
Energy can be _________ from one form to another but can’t be _______ or _________ this is called conservation of energy.
Energy can be transferred from one form to another but can’t be created or destroyed this is called conservation of energy.
How do you calculate energy input?
Energy input= useful energy + wasted energy
______ energy is energy that is not in a useful format that is ___________.
Wasted energy is energy that is not in a useful format that is dissipating.
How do you calculate work done?
Work done = force applied x distance moved
How do you calculate efficiency?
Efficiency = useful energy transferred ÷ total energy supplied by the device
How do you calculate power?
Power = energy transferred to appliance ÷ time taken for the energy to be transferred
An energy transfer of 1 Joule per second is equal to a power of _ ____
An energy transfer of 1 Joule per second is equal to a power of 1 Watt
what is kinetic energy
energy stored in moving objects
what is the equation for kinetic energy
Ek= 0.5 x m x v^2
why type of energy is petrol
chemical energy
when we stretch a spring we are applying _____ to change the ______ of the spring.
this is what scientists call ‘doing ____’
when we stretch a spring we are applying force to change the length of the spring
this is what scientists call ‘doing work ‘
we are putting ______ in to stretch the spring. the stretched spring is storing this energy and we call that energy _______ _________ ______.
we are putting energy in to stretch the spring. the stretched spring is storing this energy and we call that energy elastic potential energy
if there is no force on the spring there is also no….?
no force = no extension
what is the symbol for extension
lower case (e)
true of false?
the extension is directly proportional to the force applied
true
if you were to plot this, you would get a straight line running through 0
what happens to the extension if you apply to greater force
the extension is no longer directly proportional to the force
the spring has been stretched beyond the limit of proportionality
what is the equation for elastic potential energy
Ee= 0.5 x k x e^2
in this equation what does the k stand for
the spring constant
in this equation what does the e stand for
the extension
what unit is the extension measured in
metres (m)
what is gravitational potential energy
the energy stored in an object due to its position above the earths surface
how do you calculate gravitational potential energy
Ep= m x g x h
what is thermal energy
the energy stored due to an objects temperature
what is a system
an object or a group of objects
what is a closed system
when no energy can be passed in or out of the system
explain the energy transfer in a pendulum
- at the top the mass has the maximum store of gravitational potential energy
- as the pendulum swings the energy is transferred into kinetic energy
- the kinetic energy is highest at the bottom as this is when the mass is moving the quickest
- the kinetic energy store then transfers back to gravitational potential energy at the top of the pendulum
what could be a problem with this energy transfer
friction
as the pendulum swings where is friction found
- friction in the fixed point
- friction as the pendulum passes through the air particles
friction causes energy to be transferred to _______ energy
friction causes energy to be transferred to thermal energy
what do scientists call this energy
dissipated energy (wasted energy)
what will this ‘wasted’ energy do to the pendulum
cause it to gradually swing with less energy and eventually stop
how can you reduce unwanted energy transfers
by reducing friction
how can you reduce friction
- using a lubricant such as oil on the fixed point
- remove the air particles from around the pendulum
explain the energy transfer for a bungee jumper
- all energy in the system is gravitational potential energy
- the jumper falls and the enemy is transferred to kinetic energy
- as the bungee cord starts to tighten the kinetic energy is at its maximum
- once the cord is fully extended kinetic energy is at 0 (not moving)
all energy has been transferred to elastic potential energy - the cord recoils and the energy is transferred back to kinetic
- during ascent the kinetic energy gets transferred into gravitational potential energy
- top of the ascent all energy is now gravitational
why does the jumper never return back to its original position
energy is dissipated as thermal energy
why is the energy dissipated
due to friction
- with air particles
- stretching effects in the bungee rope which is not fully elastic
