Energy on the Loose
What is lost energy and why is it a problem?
Energy on the Loose
 Every system needs energy. Without energy, a system will not
work.
 Scientists understand that energy cannot be destroyed, or vanish
into nothing, but, it can “escape” from a system when not used.
 This “escape” of energy is often referred to as lost energy.
Lost Energy
 Energy can be lost in two ways:
 Energy can be lost when it is transformed from one form to another (for
example, when a piece of wood is burned, the wood transforms into ash
through the burning. The heat released from the fire is lost).
 Energy can also be lost when it is transferred from one part of the system
to another (for example, when you turn on a lawn mower, energy is being
transferred from the fuel to the motor. Some energy is lost in the form of
sound.).
Lost Energy in Mechanical Systems
 In mechanical systems, energy is most often lost as parts of the system
warm up due to friction.
 Energy may also escape from mechanical systems through excess
vibration and unwanted sound.
 Cars are notorious energy wasters. Less than 20 % of the gasoline’s
energy is actually used to move the car.
The remaining energy is lost through such
things as hot exhaust gases (fumes), heating
the water in the car’s cooling system,
overcoming friction in the car’s
moving parts, vibration, and sound.
Lost Energy in Social Systems
 Social systems also need to be carefully
designed and managed.
 An effective cleaning service, for example,
would be one that cleans homes to the
customer’s satisfaction.
 The service would not waste cleaning
materials, time, or electrical energy.
 Now, think about those times when you
are asked to clean your room.
 In what ways do you create “lost energy”
when performing this service?
Energy Watchdogs
 Energy losses are not only costly, they consume resources.
 Burning more gasoline and natural gas than needed wastes valuable fossil
fuel.
 Wasteful use of electricity places more strain on the electrical delivery
system.
 Canadians use large quantities of energy to keep their homes cool in the
summer and warm in the winter.
 Sometimes thermal energy escapes from homes through:
 poorly insulated walls and roofs
 through gaps around windows and doors.
 When this occurs, additional resources are used to replace the lost
energy.
 CHECK YOUR LEARNING
1. (a) In your own words define “energy.”
(b) Since energy cannot be destroyed, what do we mean when
we say that energy is lost from a system?
(c) What is the most common way that energy is lost in
mechanical systems?
2. What does friction have to do with energy losses?