Topic 1 Conservation of energy and power

Question 1

What is the conservation of energy principal

Answer 1

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

Question 2

What is dissipated energy also known as

Answer 2

Wasted energy because the energy is being stored in a way that is not useful (usually energy has been transferred into thermal energy stores)

Question 3

What is Power

Answer 3

The rate of energy transfer
Or
the rate of doing work

Question 4

What is power measured in

Answer 4

Watts

Question 5

Power equation

Answer 5

P = e/t. Or p= w/t

E= energy transferred. W= work done

Question 6

What makes something powerful

Answer 6

Transfers a lot of energy in a short space of time

Question 7

Wasted energy in phones

Answer 7

Mobile phone is a system
Energy is usefully transferred from the chemical energy store of the battery in the phone but some energy is dissipates to the thermal energy store of the phone causing it to heat up

Question 8

Describe energy transfers for closed systems using spoon

Answer 8

Cold spoon is dropped into an insulated flask of hot sop which is then sealed.
Assume that the flask is a perfect insulator so spoon and soup is a closed system
Energy transferred from thermal energy store of soup to useless thermal energy store of spoon.
Causes soup to cool down slightly
Energy transfers have occurred within the system but no energy has left the system so had a net change of zero