conservation of energy and power

What is the conservation of energy principle

Energy can be transferred usefully stored or dissipated but can never be created or destroyed

What happens when energy is transferred between stores?

Not all of the energy is transferred usefully into the store that you want it to go to some energy is always dissipated when an energy transfer takes place

Why is dissipated energy sometimes called wasted energy

Because the energy is being stored in a way that is not useful

What is a system

Portion of the physical universe that you’ve chosen to analyse

What is everything outside that system called

the environment

Why is a phone an open system and explain what an open system is ?

Phone is an open system because energy and matter can freely move between phone and environment

An open system is a system that exchanges both energy and matter with its environment

Why is a phone sealed in a jar a closed system and what is a closed system ?

If phone is in sealed jar the system is the whole content of jar including the air in the jar and the phone this is then called a closed system we energy and matter can’t enter or escape

What is power

The rate of energy transfer or the rate of doing work

What is power measured in

Watts

1 watt =1 joule of energy transferred per second

What are the power equations

P=e/t

Power = energy transferred(j)/time (s)

P=w/t

Power= work done(j)/time(s)