8. Energy LossEnergy on the Loose

- Every system ___________ energy. Without energy, a system will _______ work.

- Scientists understand that energy cannot be _________________, or ___________ into nothing, but, it can “escape” from a system when not used.

- This “escape” of energy is often ___________________ to as lost energy.

Energy Lost

- Energy can be lost in two ways:

- Energy can be lost when it is transformed from one ___________ to _______________ (for example, when

a piece of wood is burned, the wood transforms into ash through the ______________. The __________ released from the fire is lost).

- Energy can also be lost when it is transferred from one ____________ of the _______________ 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 _________________.).

Lost Energy in Mechanical Systems

- In mechanical systems, energy is most often lost as parts of the system warm up due to __________________.

- Energy may also escape from mechanical systems through excess ___________________ and unwanted

_____________.

- Cars are notorious energy _________________. Less than 20 % of the _______________________ energy is actually used to move the car.

- The remaining energy is lost through such things as hot ____________________ gases (fumes), heating the water

in the car’s _________________ system, overcoming ___________________ in the car’s moving parts, vibration, and sound.

Lost Energy in Social Systems

- Social systems also need to be carefully ___________________ and _____________________.

- An effective cleaning service, for example, would be one that cleans homes to the customer’s

_______________________.

- The service would not waste ___________________ materials, time, or _____________________ energy.

- Now, think about those times when you are asked to clean your room.

- In what ways do you _______________ “lost energy” when performing this service?

Energy Watchdogs

- Energy losses are not only _______________, they _____________________ resources.

- Burning more gasoline and natural gas than ____________________ wastes valuable fossil fuel.

- Wasteful use of electricity places more _____________ on the electrical delivery system.

- Canadians use large _______________________ of energy to keep their homes ___________ in the summer and

____________ in the winter.

- Sometimes _________________ energy escapes from homes through:

- poorly ______________________ walls and roofs

- through gaps around ________________ and ___________.

- 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?