energy conservation and dissipation

Question 1

conseravtion principle

Answer 1

energy cant be made or destroyed

Question 2

examples of energy stores

Answer 2

kinetic
thermal
graviational and elastic pot

Question 3

ways energy can be tranferred

Answer 3

thermal
mechanical
sound
electrically

Question 4

whats an open system

Answer 4

the system of matter can lose and gain energy from its surroudnings

Question 5

whats a closed system

Answer 5

neither matter nor energy can enter or leave change stays at zero

Question 6

peneglum energy example

Answer 6

at the height of its swing it has no kinetic energy but max grav pot as it reaches the middle kinetic is max but grav is at zero. it stops swining due to it being a closed system and losing energy to air resistence

Question 7

what is work done

Answer 7

th energy tranferred to something

Question 8

work done equation

Answer 8

wd
force x distance

Question 9

where does work done against fricatin go to

Answer 9

thermal energy stores

Question 10

earths grav field strength

Answer 10

9.8N

Question 11

what si weight

Answer 11

grav field strength x mass

Question 12

grav pot equation

Answer 12

grav pot =
height x weight (mass x grav field strength0

Question 13

Whats kinetic energy

Answer 13

energy stored in moving objects

Question 14

kinetic equation

Answer 14

ke

1/2 x m x s2

Question 15

whats elastic pot

Answer 15

work done on an object to stretch it, it stores elastic pot

Question 16

elastic equation

Answer 16

EP= 1/2 x k x e2

1/2 x extention2 x spring consant

Question 17

what is wasted energy

Answer 17

when energy is wasted on things that arent their intention, theure dissipated (spread out) in the surroudnings
eg in a plane kinetic for movement and grav pot for flying is useful, but thermal and sound is not

Question 18

efficiency equation

Answer 18

useful output =
efficiency x total power

Question 19

as energy dissipates….

Answer 19

it becomes less useful. eg heated pipes lose energy to radiators which lose it to the air

Question 20

ways to improve efficiency

Answer 20

lubricate to reduce friction
streamline shapes for less air resistence
use wires with less electrical resistence

Question 21

ways energy to the home is supplied

Answer 21

gas
oil
electricity

Question 22

what is power

Answer 22

rate of energy transferred/ work done per sec

Question 23

power equation

Answer 23

energy tranferred/ work done =
power x time

Question 24

whats power measured in

Answer 24

watts

Question 25

explain energy tranfer in a bungee jumper

Answer 25

begins with it all in gravitational pot, as the person falls the kinetic increases and as the rope tightens the kinetic slows and goes to the elastic potential, they rise back up losing elastic to kinetic and kinetic to grav pot, continue this until it is all lost to surroundings via thermal as the rope stretches

Question 26

things that affect grafitational pot between two objects

Answer 26

• distance between
• masses

Question 27

whats a thermal energy store

Answer 27

• kinetic
• potential