Conservation of energy and power Flashcards
what is energy measured in
Joules (J)
what is the conservation of energy
energy can never be created or destroyed, just transferred, stored or dissipated
meaning of dissipated
spreading out into the surroundings
why is dissipated energy seen as wasted energy
because it’s not useful
what is power
the rate of doing work, the rate of energy transfer
what is power measured in
watts
formula for power
power = work done / time
OR
power = energy transferred / time
OR
current squared x resistance
what is a system
an object or a group of objects
what is a closed system
one where no energy can enter or leave the system
what are problems with using the pendulum model for energy transfer
- friction is not considered
- there is friction in the fixed point and theres friction between the fixed point and the air particles
- the friction causes the point and the air around the pendulum to get warmer
- it is dissipated
how to reduce unwanted energy transfer in a pendulum
by reducing friction in the following ways :
- using a lubricant
- removing the air particles from around the pendulum
why does a bungee jumper never return back to its original position
because energy is dissipated as thermal energy
- this is due to friction with air particles
- and due to the fact that the bungee rope is not fully elastic
what is power
- the rate at which energy is transferred
OR - the rate at which work is done
