conservation of energy and power

Question 1

what is never destroyed?

Answer 1

energy

Question 2

what is the conservation of energy?

Answer 2

energy can be transfer useful , stored or dissipated, but never be created or destroyed

Question 3

what is dissipated energy?

Answer 3

wasted energy

Question 4

what is the useful and dissipated energy in a phone?

Answer 4

chemical energy is useful, thermal energy is wasted

Question 5

what is an example of an energy transfer of a closed system?

Answer 5

a cold spoon is dropped in a flask of hot soup which is sealed, they form a closed system and energy is transferred from the thermal of soup to the spoon

Question 6

what is power?

Answer 6

the rate of doing work

Question 7

how can power be calculated?

Answer 7

power (w) = energy transferred / time

Question 8

example: it takes 8000J of work to lift and object, motor A can lift it in 50s and motor B would take 300s, which motor is more powerful?

Answer 8

motor A because it does it quicker

8000 / 50 = 160 W